Larson Davis 824 Technical Reference Manual
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Larson Davis 824 Technical Reference Manual

Precision sound level meter & real time analyzer
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Table of Contents

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Model 824
Precision Sound Level Meter
& Real Time Analyzer
Reference Manual

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  • Page 1 Model 824 Precision Sound Level Meter & Real Time Analyzer Reference Manual...
  • Page 3 Larson Davis Model 824 Technical Reference Manual I824.01 Rev P...
  • Page 4 Changes and improvements to the information described in this manual may be made at any time. Record of Serial Number and Purchase Date Model 824 Serial Number: ___________ PRM902 Preamplifier Serial Number: ___________...

  • Page 5: Table Of Contents

    Using Alkaline Batteries or Individual NiMH rechargable cells....1-19 Using the AC Power Adapter..............1-20 Chapter 2 Overview System 824 Setups or Instrument Definitions ............2-1 Instrument Definition (ID) Types ................2-2 Write Protect, Delete, Write Enable IDs............2-2 SLM&RTA (SSA) .....................2-2 SLM (ISM) ......................2-4 Logging (LOG) ....................2-4...
  • Page 6 824 Reference Manual Pausing Measurements..................2-8 Back Erasing ....................2-8 Changing the detector of the displayed SPL value ..........2-8 Changing the frequency weighting of the displayed SPL value ......2-9 Changing the displayed secondary parameter..........2-10 Changing the frequency weighting of the displayed Lpeak value ....2-10 Changing the amplitude range, or input Gain ..........2-10...
  • Page 7 Power Monitor ....................3-33 Communication ....................3-34 P Print Key......................3-37 Chapter 4 Quick Start Turning On and Calibrating the System 824 ............4-1 High Range Calibration ..................4-4 Taking Measurements and Storing Data..............4-5 SLM&RTA Measurements ................4-5 Viewing RTA Displays during a Measurement ..........4-8 Recalling Stored Data ...................4-11 Selecting and Modifying Instrument Definitions (IDs) ........4-12...
  • Page 8 824 Reference Manual SSA Displays Including 1/1 or 1/3 Octave Spectral Data......5-11 Tabular SSA Views..................5-12 Time History Displays ................5-13 SSA Intervals....................5-13 SSA Time History ..................5-16 Run Log.......................5-19 Ln Centiles ....................5-19 Logging SLM Specific Views ................5-23 Current SLM and Overall SLM Views ............5-25 Current SLM/Overall SLM Display-a (SPL) ..........5-26...
  • Page 9 Wind-a Display ...................5-69 Wind-b Display ...................5-70 Wind-c Percent Display ................5-71 Chapter 6 System 824 Virtual Instruments System 824 Virtual Instruments ................6-1 Selecting an Instrument ID ..................6-3 Sound Spectrum Analyzer (SSA) ................6-3 SSA Measuring Ranges ..................6-4 LN Percentiles (Spectral) ...................6-5 AC/DC Output ....................6-5 Logging SLM......................6-7...
  • Page 10 824 Reference Manual Common SLM Settings..................7-5 Title Setting - (SSA, LOG, ISM) ..............7-5 Detector Setting - (SSA, LOG, ISM) ..............7-5 Weighting Setting - (SSA, LOG, ISM) ............7-6 Gain Setting - (SSA) ..................7-6 Range Setting - (LOG, ISM) ................7-7 Transducer Setting - (SSA, LOG, ISM) ............7-8 Random Incidence Microphone Correction - (Available to all Instrument types) ......................7-8...
  • Page 11 824 Reference Manual SPL Excd Lvl 2 - (LOG, SSA) ..............7-23 PK Excd Lvl 1 - (LOG, SSA) ...............7-24 Pk Excd Lvl 2 - (LOG, SSA) ................7-24 Hysteresis - (LOG, SSA) ................7-24 LOG and SSA Wind/Tach Settings ..............7-25 Setup of Wind/Tach Function ..............7-26 Wind Scale ....................7-27...
  • Page 12 824 Reference Manual T.H. Period - (LOG) ..................7-41 Excd Trigger - (LOG)..................7-41 Excd Time - (LOG) ..................7-41 Timed Excd Period - (LOG)................7-41 Daily Enable - (LOG)..................7-42 Daily Ln’s - (LOG)..................7-42 Logging SLM Define Report Settings .............7-42 Data Report - (LOG, SSA)................7-43 Setup Report - (LOG, SSA) ................7-43...
  • Page 13 Excd History Check Menu ................7-77 Daily History Check Menu .................7-78 Chapter 8 Printing a Report Connecting the 824 to a Serial Printer ..............8-1 Printing Reports ......................8-2 Defining and Printing Tailored Reports..............8-5 Using the Recall Format (SSA and LOG instruments only)......8-7 Default Settings Values for the Recall Format Reports ........8-8...
  • Page 14 Adding Notes to a download file ..............10-21 Selecting Active Measurements or Data Files ..........10-21 Downloading the Measurement ..............10-22 Explanation of files in the 824 Utility Directory ...........10-24 Translating Data from a Downloaded Binary File..........10-25 Selecting a Data set to view ................10-27 Printing a Translated File ................10-29...
  • Page 15 Calibrating dB to a Different Reference ............12-13 Displaying Amplitude in Linear Units............12-14 Setup of Linear Units Readout..............12-15 Frequently Asked Questions Concerning FFT..........12-17 Chapter 13 AUD (Optional) 13-1 Connecting the Test System .................13-2 Selecting the 824-AUD Operation Mode .............13-3 iii-xi...
  • Page 16 Appendix A Serial Port Interface Remote Control Interface Cables .....................A-2 Connection to a computer using CBL006 ............A-3 ‘Daisy Chain Addressing ..................A-5 824 Network, Addressing Commands ..............A-6 Commands ......................A-8 Remote Control Commands (Detailed) ..............A-9 Mode Commands ....................A-9 “Read” Commands (Reads out data variables) ..........A-10 “ANY DATA”...
  • Page 17 Time History Variables (SSA, LOG, TAL) ............A-68 Histogram Table Variables ................A-68 Print Command ....................A-69 Error Messages and Warnings ................A-71 Modem Control Mode (All Instruments).............A-74 Modem Mode ....................A-74 Dial Out Mode ....................A-74 Monitor Number .....................A-75 824 Phone Dialing Procedure .................A-75 Model 824 Answering Procedure ..............A-76 iii-xiii...
  • Page 18 1/1 and 1/3 Octave Filters ................C-20 Frequency Range..................C-20 Filter Shapes:....................C-20 Frequency Response ..................C-24 Power/Current Draw of 824 Using External Power........C-49 Appendix D Glossary Allowed Exposure Time (Ti) ...............D-1 Average Sound Level (Lavg) ...............D-2 Community Noise Equivalent Level (CNEL, Lden)........D-2 Criterion Duration (Tc) ................D-3...
  • Page 19 Time History Records (Time History Enabled) ..........E-2 Other Histories and Memory Usage..............E-2 Estimating Memory Usage: ................E-3 824-LOG Memory Usage Worksheet ............... E-5 824-SSA Memory Usage ..................E-7 Interval Records (Intv History Enabled) ............E-7 Time History Records (Time History Enabled) ..........E-8...
  • Page 20 824 Reference Manual Reference Sound Pressure Level:..............F-1 Reference Level Range: ................F-1 Microphone Reference Point:............... F-1 Average Frequency Response Corrections ..........F-2 Periodic Testing of A-Weighted Sound Levels..........F-4 A-Weighted Sound Levels at Upper and Lower Limits of the Linear Operating Range......................

  • Page 21: Chapter 1 Introduction

    Chapters • Chapter 1 - Introduction: Orients the user to the contents of this user manual and the System 824’s features, functions and measurement capabilities. It also includes instructions on unpacking the System 824. • Chapter 2 - Overview: Provides an overview of the instrument’s capabilities and a description of each key...
  • Page 22 • Chapter 10 - Using the 824 Utility Software: Describes how to connect the 824 to a computer, in order to download, translate and export data. • Chapter 11 - RTA (Optional): Explains how the RTA...

  • Page 23: Special Features Of The Electronic Version

    System 824 according to IEC61672-1. Appendix G - Miscellaneous Information: Contains • additional information about the 824 in the form of questions and answers Special Features of the Electronic Version There are a variety of special techniques for navigating through pdf documents which can greatly simplify finding specific items in this manual.

  • Page 24: Closing Bookmarks

    + to the left of any chapter will expand it into major headings and, by clicking all the + symbols, the complete tree for that chapter will be shown. In the following figure we can see the entry System 824 Virtual Instruments completely expanded. 824 Reference Manual...

  • Page 25: Click To Display Page

    Click to Display Page Left click on any text field (Chapter name, Appendix name, Table of Contents, Index, or any sub heading) and the page displayed on the right will jump to the page associated with that text field. Return to Previous View To return to the page which was displayed previous to clicking on a bookmark text line, right click on the display page, then left click on “Go to Previous View”.

  • Page 26: About This Chapter

    Formatting Conventions: Provides an explanation of the fonts and other formatting conventions used in this manual. • Features: Gives an overview of the System 824 keypad, functions and measurement capabilities. • Getting Started: Provides instructions for unpacking, inspecting and initially assembling the System 824.

  • Page 27: Features

    Features Hardware Features: The Larson Davis System 824 has the following features: • Large backlit bitmapped graphic display • Soft rubber backlit keys • Pop-up menus with scroll bars • Pick and choose setup...just click and run! • File management system (stores multiple measurements) •...
  • Page 28 Measurement of windspeed (tacho) and wind direction direction (throttle position) feature (throttle position) using external weather transducers requires the firmware option 824- with inclusion of data in Views and Data Displays for WND, not included with standard SSA and LOG instruments.
  • Page 29 - 12,300 SSA intervals with Leq & Max 1/3 octave spectra - 60,000 LOG intervals without Ln - 35,000 LOG intervals with Ln - 1,000,000 point time history - 70,000 RTA 1/1 octave spectra - 28,000 RTA 1/3 octave spectra - 2400 FFT 400 line snapshots •...

  • Page 30: System 824 Components

    9 cm (3.5”) Figure 1-1 The System 824 is a convenient hand-held sound level meter with a simple user interface. The standard System 824 shown in Figure 1-1 includes the following: • 1/2” diameter condenser microphone • Backlit graphic 64 x 128 pixel LCD display •...
  • Page 31 Serial Interface Connector External DC Power Connector Figure 1-2 The System 824 has a series of connectors located at the bottom of the device consisting of an AC and DC output connector, control connector, serial interface connector, and external DC power connector.
  • Page 32 Both outputs have a 600 ohm series The AC/DC output connector is used to output the signal resistance. from the System 824 microphone to external devices such as DAT recorders, real-time analyzers, other sound/vibration measurement equipment, voltmeters, chart recorders, etc.

  • Page 33: System Diagram

    System Diagram Figure 1-6, illustrates the acoustic-to-digital signal path in the System 824. As you can see, incoming sound is first converted to an electrical signal by the microphone. This electrical signal is amplified, filtered and then sampled by an analog-to-digital converter (ADC).

  • Page 34: Getting Started

    • Connecting Internal or External Power • Environmental Considerations You will then be ready to use the System 824 for actual measurements. Unpacking and Inspection Your System 824 has been shipped in protective packaging. Please verify the package contains the items listed below.
  • Page 35 Figure 1-6 System Diagram Sysjklsfdakjl;fasdjl;kasdflj;ksdfal;jkklj;kl Figdfdsafdsa 9/29/09 Introduction 1-15...

  • Page 36: Comments Concerning The Digital Signal Processor

    Impulse and Peak detectors damage to the instrument. Accessories and Optional Equipment The System 824, 824S, 824L and 824A can be purchased with or without a microphone; they all include the Model PRM902 microphone preamplifier. The System 824, 824L and 824A are delivered with the...
  • Page 37 • Hard case 15”x19”x7” (CCS001) with foam insert (0860.0077) • Windows utility software (SWW_824_UTIL) • 10 foot microphone extension cable (EXA010) • 3 1/2” diameter windscreen (WS001) The 824S is delivered with the following standard accessories (824S Pack): • 3 x 1.5 V “AA” alkaline batteries •...

  • Page 38: Connecting Internal Or External Power

    Using the NiMH Battery Pack To use a NiMH battery pack (BAT010) with the System 824, unscrew the battery cover at the back of the System 824 by hand or using a flat blade screwdriver. If individual cell batteries were previously used, remove the Terminal For additional battery information, Assembly (Figure 1-8).

  • Page 39: Using Alkaline Batteries Or Individual Nimh Rechargable Cells

    If the rechargeable LD BAT010 battery pack is used, the setting is overridden and assumed to be NiMH. The 824 will automatically detect the presence of the pack, so the setting can be left to what would most likely be used if individual cells were to be used instead of the battery pack.

  • Page 40: Using The Ac Power Adapter

    Using the AC Power Adapter You may use an external power source via the external power connector using the provided power adapter. The System 824 accepts 6 to 15 VDC and is internally fused at 0.5 A. 1-20 824 Reference Manual...

  • Page 41: Chapter 2 Overview

    C H A P T E R Overview This Chapter presents a general overview of the structure of the Model 824, an example of selecting a Setup or Instru- ment Definition (ID), performing a measurement and storing the data. Subsequent chapters will deal specifically with these steps in a more structured manner.

  • Page 42: Instrument Definition (Id) Types

    In addition to a live spectrum display, the System 824 can display an equivalent level (L spectrum, a minimum bin by bin level (L ) spectrum and a...
  • Page 43 80 dBA. The design of the System 824 permits the simultaneous measurement of the following sound level parameters, a feature we call “Any Data”:...

  • Page 44: Slm (Ism)

    105 dBA and does not provide frequency spectrum measurement capability. Up to thirty-six measured sound level parameters can be stored as a Time History record at rates as rapid as 32 samples per second. 824 Reference Manual 9/29/09...
  • Page 45 The following parameters can be logged at user-selectable time intervals between 1 second and 99 hours (hh:mm:ss) • , SEL, and L (q=3) or Time Weighted Aver- age (q=4, 5, or 6) levels for a selected detector (Slow, Fast, or Impulse) and a selected frequency weighting (A, C, or Flat) •...

  • Page 46: Selecting A Measurement Setup

    At any time, one of the available setups will be the active setup. The name of this setup will be at the top of the list below the Edit Setting message. Pressing the key while the “Edit Settings” menu item is highlighted initiates the modification procedure. 824 Reference Manual 9/29/09...

  • Page 47: Performing A Measurement; Slm&Rta (Ssa)

    Performing a Measurement; SLM&RTA (SSA) Without getting into the fine details of operating the System 824, let’s just press some keys and see what it can measure and display. Step 1 Let’s look at the SLM&RTA (SSA) ID Access the...

  • Page 48: Stop, Pause And Back Erase Functions

    Changing the detector of the displayed SPL value You can change the parameters being displayed in the View window while a measurement is in progress without going to the Setup menu. 824 Reference Manual 9/29/09...

  • Page 49: Changing The Frequency Weighting Of The Displayed Spl Value

    Step 1 To change to the detector type, use the keys to highlight the Slow detector, as shown below: Step 2 To scroll through the optional detectors, press the arrow keys. This will display the SPL corresponding to the Fast and Impulse detectors. Go back to the Slow detector and press the check key or wait several seconds until the highlight disappears.

  • Page 50: Changing The Displayed Secondary Parameter

    80 dB, unlike the ISM and LOG IDs for which it is 105 dB. In order to optimize a particular measurement, provisions have been made to select a value of input gain directly from the graphic display. The gain can 2-10 824 Reference Manual 9/29/09...

  • Page 51: Views

    also be changed from the Setup Menu, as described later in this manual or it can be changed here. Step 1 To change the gain, Use the keys to highlight the Gain, as shown below The gain shifts the dynamic range up or down.
  • Page 52 Sound Level parameters and spectral data measured and automatically stored at user defined time periods. Run Log Displays the start and stop times/dates of the active measurement. Ln Centiles L1 - L99 displayed for the measurement period. 2-12 824 Reference Manual 9/29/09...

  • Page 53: Data Storage And Recall

    As part of this exercise, select each of these various VIEWs and use the keys to see how a variety of different parameters are displayed within each function. We have sought only to explain the general concept of the VIEW function at this time. More detailed explanations are provided later in Chapters 3 and 6.

  • Page 54: Calibration

    Calibration is one of the functions available from the Tools connecting microphone Menu. preamplifier; the high voltage spike Step 1 Press the TOOLS key. created when connecting while the instrument damage sensitive electronic components. Step 2 Press the key to highlight “Calibration”. 2-14 824 Reference Manual 9/29/09...
  • Page 55 Step 3 To setup the calibration process, press the to move into the Calibration Menu. Step 4 To set the calibration level, press the keys to highlight “Cal Level”, Step 5 To set the value of the sound level provided by the NOTE: The output level specified by the calibrator manufacturer will be at calibrator, press the...
  • Page 56 Step 10 If the calibration is not reasonably close to the level of the calibrator, the calibration can be changed by choosing Change. Press , use key to highlight “Change”. Step 11 Switch the calibrator ON, and press 2-16 824 Reference Manual 9/29/09...

  • Page 57: Correction Of Calibrator Output Level

    If the calibration sheet for the CAL200 indicates 113.98 dB for it's level when set to 114 dB then set the Cal Level in the 824 to 113.86 dB.
  • Page 58 2-18 824 Reference Manual 9/29/09...

  • Page 59: Chapter 3 Front Panel Keys; Functions And Menus

    System 824 keypad (see Figure 3-1 below): Figure 3-1 System 824 Keypad. The 14 keys on the System 824 keypad are organized into these four sections: Power, Measurement, Navigation, and Control. These keys are covered in the following order in this chapter: 9/29/09 Front Panel Keys;...
  • Page 60 Power Key Turns on / off the System 824; accesses bat- tery power monitoring and LCD utilities, POWER and is used to close menus. Measurement Keys Begins and ends measurements. RUN/STOP Pauses readings while running, Previews current SPL when stopped. Activates PAUSE Back Erase function.

  • Page 61: Power Key

    The purpose of the POWER key on the System 824 is to turn the power on or off, close menus, and display the remaining battery life. Once the System 824 is turned on, pressing the key again will activate a PWR display where you can change screen contrast, turn the backlight on or off, and adjust power options.

  • Page 62: Power-Up The Instrument / Viewing Pwr Display

    Step 3 As soon as the hour glass icon disappears, the Sys- tem 824 is ready to acquire data. As soon as the System 824 is turned on, you can view the battery life and display settings through the PWR display. To...
  • Page 63 Check menus allow you easy access The settings menu allows you to adjust the contrast (or view- to system or instrument settings. ing angle), turn the backlight on or off, and adjust settings that control the power-conservation features. These power- arrow keys, allow conservation features allow you to set the instrument to do you to select the desired menu item...

  • Page 64: Power Settings

    Select Alkaline or NiMH for individual cells. See Connecting Internal or External Power” on page 1-18 Once the smart charger has been activated the 824 will not allow you to shut it off when the power key is held down.
  • Page 65 Time (in minutes) when Standby Time power save is Standby Time 0 - 99 minutes activated. When activated, the System 824 screen blanks and the serial port turns off. If any key is pressed or if incoming serial activity is detected, the instrument will exit Standby Time and become active again.

  • Page 66: Extra Notes On Power Conservation

    If the external battery supply ever drops below 10.8 Volts, set by the Min Battery setting, the 824 will automatically turn off. Discharging some types of batteries (such as lead acid) deeply will greatly shorten their service life.

  • Page 67: R Reset Key

    This will reset all the data including the accumulated measurement values such as L The SSA, ISM, and LOG instruments For the other instrument types, the System 824 gives addi- within the System 824, contain two tional flexibility when resetting the data. If you press the...

  • Page 68: Pause Key

    NOTE: Moving the cursor bar left is like moving back in time. data to the right of the vertical bar. After the instrument has deleted the unwanted data, the measurement will resume automatically. 3-10 824 Reference Manual 9/29/09...

  • Page 69: Preview

    Preview Pressing the PAUSE key when an instrument is “stopped” brings up a Preview display which allows you to view the SPL without affecting measured data. Pressing the PAUSE key again will exit this screen or simply press RUN/STOP key to exit this screen and start taking a measurement.

  • Page 70: Check Key

    V View Key The display of data on screen of the System 824 is controlled by the VIEW key. Each instrument type (e.g. SSA, ISM, or LOG) has its own set of available data displays which are selected using this key.

  • Page 71: D Data Key

    D Data Key DATA key controls the storing and recalling of measurements, or data files from memory. Each file may contain cumulative data, time history, interval history, cali- bration data and histogram tables that can be stored as dis- tinct measurements from other measurements with their data and histories.

  • Page 72: S Setup Key

    Pressing the key from the Data When recalling a data file, the System 824 will switch to the Files display, brings up a menu that instrument definitions (ID) that the data file was stored as allows you to recall data, jump to (i.e.
  • Page 73 ID on a computer using the 824 Utility soft- ware and then install it into the instrument where it may be selected for use. For example, one project may require the “simple SLM” where no data logging is performed and the weighting and detector controls are available in the data dis- play (rather than in a menu).

  • Page 74: Save Id

    ^ &. The allowed characters in names for IDs are compatible with PC filenames. The following characters are NOT allowed: * + , . / : ; < = > ? [ \ ] | 3-16 824 Reference Manual 9/29/09...

  • Page 75: Write Protect, Delete, Write Enable Ids

    Write Protect, Delete, Write Enable IDs After an ID has been created, it can be protected (or locked), NOTE: Within a given active instrument definition (ID), write protect or delete or deleted if necessary. To do this, use the keys operations cannot be performed on files from the Setup menu to highlight the desired ID.

  • Page 76: Ttools Key

    Date Format (Normal or ISO- 8601) Takt (enables Takt functional- ity) Yes or No Calibration Check Calibration - dates, times, and measure- Change ment when checked or changed Cal Level Calibrator S/N Noise Floor (not all versions) 3-18 824 Reference Manual 9/29/09...
  • Page 77 Clock/Timer Current Time a - Current time, date, and time of next Current Date action Day of Week b - Timer mode status and settings Timer Mode Run Date Stop Date Run Time 1 Stop Time 1 Run Time 2 Stop Time 2 Memory Delete Last...

  • Page 78: About

    The About-b display shows the instrument’s custom name firmware code modification is made and title fields printed on System 824 reports. The fields are that affects the accuracy of any SLM generally set to the owner’s name and address. The name is measurement data, and is used as an displayed at “power on”...
  • Page 79 Company name and address (Customized by user) provides 30 alpha/numeric characters, and is used to describe the instrument or the organization to whom it belongs. Title - Like the Company Name field, the Title field is capa- ble of holding 30 alpha/numeric characters. It allows you to title the ID (Instrument Definition) you have created, and to describe your measurement.

  • Page 80: Calibration

    If you have found them useful, they can be installed permanently without restrictions. Call Larson Davis for details. Calibration To calibrate the System 824, or to view previous calibration information, use the key to select Calibration from the Tools menu, then press the key.

  • Page 81: Clock/Timer

    Change - Activates the calibration change (adjust) process. Cal Level - Enables the user to enter the sound pressure level generated by the calibrator. Calibrator S/N - Enables the user to record the serial num- ber of the calibrator (for reference). Noise Floor - Enables the user to enter a noise floor value.
  • Page 82 The first run and stop times The time of the next timer function key. A screen similar to the following will appear: The clock in the 824 uses a 24 hour format with hours 0 through 11 being a.m. and hours 12 through 23 With the Clock / Timer menu you set the instrument's clock/ being p.m.
  • Page 83 Timer Mode - The timer is used when you want to have the 824 automatically turn on, gather data, and stop at pre-deter- mined date(s) and time(s). The System 824 has four timer modes automating the start and end of measurements: Off - The timer is disabled.
  • Page 84 Stop Date - Specifies the date to end the measurement and disable the timer mode. Run Time 1 / Stop Time 1 - These settings allow you to specify the beginning and ending times of a measurement. 3-26 824 Reference Manual 9/29/09...

  • Page 85: Memory

    Block, NOTE: If you have selected the 1/Day 2/Day mode, the timer will automatically turn the instrument on one minute prior to the run time. Run Time 2 / Stop Time 2 - These settings are used to spec- ify a second measurement’s beginning and ending time in the 2/day timer mode.
  • Page 86 Purge All Data Files - Pressing the key when the available from the reset menu under Purge All Data Files menu item is highlighted, allows you the RESET key. to purge all data files in memory. This clears the memory. 3-28 824 Reference Manual 9/29/09...

  • Page 87: Deleting Stored Data

    824 Memory Structure The memory structure of the 824 is a forward and reverse linked list. This means that for each type of data there is a pointer to the first record and a pointer to the last record and 9/29/09 Front Panel Keys;...

  • Page 88: Deleting The Last Stored Record

    Step 3 Highlight “Delete Last” and press the Check key. This display shows the last record that was stored along with the date and time of the data, the instrument type it is 3-30 824 Reference Manual 9/29/09...

  • Page 89: Deleting Individual Records

    recorded for, the bytes used by that record and how much memory is available. Step 4 Press the Check key to delete this file. The fol- lowing menu will appear: Step 5 Highlight “Delete” and press the Check key. The record is deleted. If the last record was a data file then the following choices will appear: DEL - Choosing “DEL”...
  • Page 90 Step 4 Highlight “Delete Last” and press the Check key. The records will appear one at a time. Below are examples of some of the records. To delete them press the Check key. The following will appear: 3-32 824 Reference Manual 9/29/09...

  • Page 91: Power Monitor

    With “Delete” highlighted, press the Check key again to delete the record. The next record will appear. Continue this process until you have deleted all of records that you don’t want. Power Monitor This menu option allows adjustment of the auto-power off, the contrast (or viewing angle), turns the backlight on or off and adjusts settings that control the power-conservation fea- tures.

  • Page 92: Communication

    I/O command problems. The printer has its own baud rate for Baud Rate - Speed at which the System 824 communicates printing reports and is not affected with controlling devices (computer, modem, etc.) through by this setting.
  • Page 93 Default is set to the value of the last Serial Address - Address of instrument. This setting identi- 2 digits of the serial number and can fies the instrument within a network of instruments by be set within the range of 1 to 100. assigning it a network or serial address.
  • Page 94 Dial Out Mode - The 824 will dial out on an Exceedance or an Alarm or both. Phone Number - The 824 will dial the phone number entered here on the events selected in the dial out mode. Monitor Number - The monitor number is used to identify which 824 is being queried and is sent with the 824’s initial...

  • Page 95: P Print Key

    Modem Init - The modem initialization string is entered here. Initialize - The modem initialization string is sent out the RS232 port. P Print Key Refer to the section "Printing PRINT key displays the printing options menu. Reports" on page 8-2 for more These options enable printing of graphical and tabular data information on printing.
  • Page 96 In this sub-menu you can select the specific ele- ments to include in the report and also the various data ranges for histograms, time histories, etc. To access this sub- menu, highlight Customize and press the key. 3-38 824 Reference Manual 9/29/09...

  • Page 97: Chapter 4 Quick Start

    Taking an actual measurement with the System 824 is as easy as pressing the (RUN/STOP) key. This chapter helps users begin using the System 824 immediately.
  • Page 98 This screen displays three lines of Step 1 Turn on the System 824. To do this, press the user information which may be key (located on the left side of the key pad). By defined name address pressing this key, the Larson Davis logo appears settings.
  • Page 99 Step 4 Using the key, highlight the Calibration menu item, then press the key. The following screen appears: Step 5 The value of Cal Level (3rd item on the screen) NOTE: The output level specified by the calibrator manufacturer will be at stan- must be set equal to the output level of the dard temperature and pressure.

  • Page 100: High Range Calibration

    20 dB less than the Cal Level microphone, prompt value. concerning calibration of the High Range will not appear. 824 Reference Manual 9/29/09...

  • Page 101: Taking Measurements And Storing Data

    NOTE: A solid black box indicates that Whether using the SSA, ISM, or LOG instrument, the SLM the 824 is stopped with data, and a hol- is one of the most common functions used in the System low box indicates that the 824 is 824.
  • Page 102 If this is your first time using the System 824 and you have not set up any ID’s, or have not taken any readings that need to be saved, select “No”.
  • Page 103 The screen shows a black box symbol in the upper right hand corner indicating that the instrument stopped taking measurement. If you attempt to store data while a Step 6 To store the current measurement readings, press measurement is still running a Data key.

  • Page 104: Viewing Rta Displays During A Measurement

    Tabular mode. Step 3 Use the arrow keys to highlight the RTA item and press the Check key to select the RTA displays. A screen similar to the following appears: 824 Reference Manual 9/29/09...
  • Page 105 The RTA Live screen shows a graphical display of the sound readings over a range of frequencies. The SPL for the selected frequency is displayed in the upper left corner. The frequency, as selected by the vertical cursor, is displayed in the lower left corner.
  • Page 106 If you attempt to store data while a Data key. Select Store Data and measurement is still running, a press the key to store the measurement’s data. warning will displayed, indicating that the measurement must first be stopped. 4-10 824 Reference Manual 9/29/09...

  • Page 107: Recalling Stored Data

    When recalling a data file, the Step 2 Use the up and down arrow keys to System 824 will automatically switch highlight “Recall Files” and press the check to the instrument that the data file key. The following appears: was stored as (i.e.

  • Page 108: Selecting And Modifying Instrument Definitions (Ids)

    As explained in the section "System 824 Setups or Instrument Definitions" on page 2-1, the way to prepare the System 824 for a measurement is to select an existing Setup or Instrument Definition (ID) from the list which appears on...

  • Page 109: The Setup Menu

    The Setup Menu Pressing the Setup key will produce a display similar to the following: The Active ID The first item in the list is the Active ID, which will be highlighted. If the user exits from the Setup Menu by pressing either (a second time) or , the instrument is...
  • Page 110 “~” will appear to the left of the Active ID to indicate that it is approximately the same as another ID in the list. 4-14 824 Reference Manual 9/29/09...

  • Page 111: Menu Scrolling

    Menu Scrolling There may be more items in a menu than can be shown in a single display. To the right of any menu window, there will be a vertical window within which there will be vertical bar. If this vertical bar extends from the top to the bottom of the vertical window, then all items in the list are shown in the display.

  • Page 112: Write-Protected Ids

    Setup key or to exit from the Setup menu. The System 824 is now ready to perform a measurement If data has been taken, the prompt according to the Setup represented by the Active ID. If the Active ID is not satisfactory for the measurement, the following options are available: •...

  • Page 113: Selecting A Different Id

    Settings menu and sub- menus. Please follow this on your instrument. Since all versions of the System 824 include the SSA Instrument Type, we want to select the permanent ID SLM&RTA (SSA) as the Active ID. Press to open the Setup menu.

  • Page 114: Accessing The Settings Menu To Initiate Editing Or Modification

    Note that all of the items in this list, with the exception of the first, Title, have the symbol “>” to the right indicating a sub-menu. In order to illustrate the Settings menu structure, please perform the following steps to set the SLM Weighting function. 4-18 824 Reference Manual 9/29/09...
  • Page 115 Step 1 Use to highlight SLM Step 2 Press to produce the SLM sub-menu Step 3 Use to highlight Weighting (note that the present selection is “A”) Step 4 Press to open SLM Weighting Selections menu Step 5 Use to highlight “FLT” 9/29/09 Quick Start 4-19...
  • Page 116 To better understand what happens when we back out of the Setting menu structure using repeated presses of consider the following diagram illustrating the actions which 4-20 824 Reference Manual 9/29/09...
  • Page 117 have been taken so far in the example above. In this particular instance, when the key was used to move from the Settings menu to the SLM sub-menu and from the SLM sub-menu to the Selections menu, the item highlighted was not the first in the list. Observe that when was pressed to accept the selection of “FLT for the frequency weighting, upon returning to the Weighting sub- menu, the 2nd item was highlighted, just as it had been...

  • Page 118: Setting Control In The Slm View

    Setting Control in the SLM View SLM settings can be adjusted from the SLM View screen. To activate the SLM view screen, turn on the System 824, press View key, highlight SLM, then press the Check key.
  • Page 119 Step 1 Press the keys to highlight the current RMS detector (Slow, Fast, Impl). Step 2 Press the key to change the selection. The table below shows how to use the arrow keys to navigate through the settings on the SLM display. Detector Slowr Fast rImpulse r Weight...
  • Page 120 4-24 824 Reference Manual 9/29/09...

  • Page 121: Chapter 5 System 824 Views

    C H A P T E R System 824 Views This chapter introduces you to the various ways of viewing measured data for a particular setup or ID of the System 824. Specifically, this chapter covers the following topics: •...

  • Page 122: Status Icons And Indicators

    Status Icons and Indicators When using the System 824 you will encounter a number of different display views. Each display contains an instrument status icon in the upper right hand corner of the display. This icon changes according to the current state of the instrument.
  • Page 123 Animated Draining Battery - The battery is low, and the instrument will shut off soon. O.L. - The instrument has been overloaded; measurement may not be accurate due to an overload condition having occurred some time during the measurement. 9/29/09 System 824 Views...

  • Page 124: General Views

    Animated Clock - Indicates that the automatic run/stop timer is active. Currently overloaded General Views The System 824 presents measurement data in both graphical numerical/text formats easy comprehension. This section provides an overview of the basic components of these display views.

  • Page 125: Slm Views

    The SLM view display consists of eight major components: • Display label • Selected detector • Current SPL reading • Selectable L reading • Weighting • Elapsed time • Status • SPL history graph 9/29/09 System 824 Views...
  • Page 126 It resets to zero when the RESET key is pressed, pauses when the PAUSE key is pressed, and continues when the PAUSE key is pressed again. The timer is displayed as mm:ss.ss, hh:mm:ss or hhhhh:mm. 824 Reference Manual 9/29/09...
  • Page 127 Detector (A, C, or Flat) (Fast, Slow, Impulse) Secondary Parameter Secondary Weighting Gain (L eq , SEL, L min , L max , L pk ) (A, C, or Flat) (0, +10, +20, +30, +40, +50 9/29/09 System 824 Views...

  • Page 128: Any Data View

    A, C and Flat weighting as peak follows: Any Impulse Format In this view, three different tables present Impulse weighted parameters alongside similar Fast weighted parameters measured with A, C and Flat weighting as follows: 824 Reference Manual 9/29/09...

  • Page 129: Any Time Format

    (Fast, Slow, and Impulse) and Lpeak measured with A, C and Flat weighting as follows: SSA Specific Views The System 824 has various displays for the SSA instrument. Understanding these displays lets you take full advantage of this instrument. In addition to the SLM and Any Data views described...
  • Page 130 There are also displays for the Interval History, the Time History, the Run Log and for Ln Centiles. Like all of the System 824 displays, these views are accessed via the View key as described earlier in the “General Views”...

  • Page 131: Ssa Displays

    The cursor or (frequency bar position) can be changed by pressing the arrow keys. As the arrow keys are pressed, the vertical bar moves 9/29/09 System 824 Views 5-11...

  • Page 132: Tabular Ssa Views

    Step 3 To return to the graphical view, press the check key and the following menu appears: 5-12 824 Reference Manual 9/29/09...

  • Page 133: Time History Displays

    (including spectral LNs) Interval-a through Interval-d gathered in time segments over the run time of the 824. An displays. example would be a measurement where data is gathered in one hour time intervals over a 24 hour period.
  • Page 134 “Interval” for the Spectra Ln setting under the “Ln” menu. In the “Interval” menu set the following settings to [Yes]. To view the Interval Spectral LN displays, press the View key and highlight “Intervals”. Intv Enable [Yes] Intv Save Ln’s [Yes] 5-14 824 Reference Manual 9/29/09...
  • Page 135 LOG option is installed. Press the right arrow key to access the “Interval” Spectral LN displays. The following menu will appear: Highlight “Spectral” and press the check key to view the INTV-Ln(f) display. 9/29/09 System 824 Views 5-15...

  • Page 136: Ssa Time History

    SSA Time History The SSA Time History display consists of six major components: • Display label • Record number • SPL reading at cursor • Other level • Status • SPL history graph 5-16 824 Reference Manual 9/29/09...
  • Page 137 The SLM Time History display is shown below: Display label Record number Time cursor Leq reading at cursor/ Detector setting SPL history graph Value of other level Other level selected in TH setup Status indicator Identifies the marker 9/29/09 System 824 Views 5-17...
  • Page 138 Cont - Indicates that the measurement continued at this time. Reset - Indicates that the measurement was reset at this time. Mark - Indicates that a marker was set at this point in time. 5-18 824 Reference Manual 9/29/09...

  • Page 139: Run Log

    “Overall”. See the section "LOG and SSA Ln Settings" on page 7-20. Highlight “Broadband” and press the check key to view the SSA-Ln-a display. Display label Percentile values & levels 9/29/09 System 824 Views 5-19...
  • Page 140 • Ln - This shows the current Ln value. • Elapsed time - Shows the elapsed run time accumulated since the last overall reset. 5-20 824 Reference Manual 9/29/09...
  • Page 141 SSA-Ln (f) display showing six Ln percent values for the frequency displayed. Use the right and left arrow • Selected frequency - Shows the values for the frequency keys to move to each 1/3 octave shown on the display frequency. 9/29/09 System 824 Views 5-21...
  • Page 142 SSA-Ln 1(f) display showing L 1.67 for all of the frequencies in graphical form. • Ln percentage - Shows Ln percentage being displayed. • Level at selected frequency - This shows the Ln level at the frequency selected. 5-22 824 Reference Manual 9/29/09...

  • Page 143: Logging Slm Specific Views

    Logging SLM Specific Views The System 824 provides a number of different displays for the Logging SLM (LOG) instrument. Understanding these displays allows you to take full advantage of this instrument. All of these views can be accessed by pressing the View key when using the Logging SLM (LOG) instrument.
  • Page 144 History level goes over a predetermined threshold. Leq, SEL, Lmax, LPK-I, LPK- II, duration and time history (if desired) are saved for each exceedance record. Can also show wind or tachometer data using external transducers. 5-24 824 Reference Manual 9/29/09...

  • Page 145: Current Slm And Overall Slm Views

    Shows wind or tachometer data. Current SLM and Overall SLM Views Current SLM clears and starts over The System 824 contains two independent data buffers that when the R Reset button is pressed can accumulate data separately. In essence, the instrument while running.

  • Page 146: Current Slm/Overall Slm Display-A (Spl)

    Current SLM/Overall SLM The Current/Overall-a SLM (or SPL) display consists of six Display-a (SPL) major components: • Display label • Current SPL reading and weight setting • Selected detector • Elapsed time 5-26 824 Reference Manual 9/29/09...
  • Page 147 SPL history graph - Shows a recent history of one second Leq readings. The far right bar displays the current SPL reading. As readings are taken, they are placed onto the scrolling graph from right to left once per second. 9/29/09 System 824 Views 5-27...

  • Page 148: Current/Overall Slm Display-B (Times)

    It will restart at zero when the Reset key is pressed (Current SLM only). It will also pause when the Pause key is pressed and then continue when it is pressed again. The timer is displayed as hhhhh:mm:ss.s 5-28 824 Reference Manual 9/29/09...

  • Page 149: Current/Overall Slm Display-C (Min/Max)

    Current / Overall Lmin reading - Displays Lmin or minimum level that occurred, and the date and time when it occurred. Current/Overall SLM Display-d The Current / Overall-d SLM or Peaks Display consists of (Peaks) three major components: • Display label 9/29/09 System 824 Views 5-29...

  • Page 150: Current/Overall Slm Display-E (Twa)

    Current/Overall C - Weighted Peak reading - Shows the C weighted value from the System 824’s peak detector along with the date and time that the peak event occurred.

  • Page 151: Exposure Views

    Exposure with the Check SLM, Overall SLM, Exposure, Ln key from within the main View menu then cycling through Centiles, and Stats views. the views with the arrow keys until the desired display appears. 9/29/09 System 824 Views 5-31...

  • Page 152: Exposure Display-A

    100% dose. Projected dose - Projected dose is the dose that will occur if current noise levels continue for the entire criterion time. 5-32 824 Reference Manual 9/29/09...

  • Page 153: Exposure-B Display

    Takt functionality has been hours (Pa H). The Sound Exposure (E) is a function of the enabled. (See the Menu Item "About" and the elapsed time of the overall measurement. on page 3-18). 9/29/09 System 824 Views 5-33...

  • Page 154: Exposure-C Display

    Timer Exposure-c Display The Exposure-c display consists of four major components: • Display label • C - Weighted TWA • A - Weighted TWA • C minus A TWA The Exposure-c display is shown below: 5-34 824 Reference Manual 9/29/09...

  • Page 155: Ln Centiles Views

    Ln-a display. display appears. Ln-a Display The Ln-a display consists of two major components: • Display label • Percentile values & levels The Ln Centiles-a display is shown below for the LOG instrument: 9/29/09 System 824 Views 5-35...

  • Page 156: Ln-B Display

    Ln-b Display The Ln-b display consists of five major components: • Display label • Current % record • • Elapsed Time • Ln graph The Ln Centiles-b display is shown below for the LOG instrument: 5-36 824 Reference Manual 9/29/09...

  • Page 157: Stats Views

    The Stats View has three displays which can be accessed by simply selecting Stats with the Check key from within the main View menu then cycling through the views with the arrow keys until the desired display appears. 9/29/09 System 824 Views 5-37...

  • Page 158: Stats-A Display

    SPL exceeded the pre-programmed trigger level 2. In this example, trigger level 1 is set to 120 dBA and the SPL exceeded this threshold 0 times. These may be considered as individual events. Stats-b Display The Stats-b display consists of three major components: 5-38 824 Reference Manual 9/29/09...

  • Page 159: Stats-C Display

    Peak-II’s trigger level is set to 140dBA and the Peak-II level exceeded this threshold 0 times. These may be considered as individual events. Stats-c Display The Stats-c display consists of two major components: • Display label • Overload message 9/29/09 System 824 Views 5-39...

  • Page 160: Run Log (Log & Ssa)

    Run Log (LOG & SSA) The Run Log displays the start and stop times/dates of the active measurement in the System 824’s memory. You use arrow keys to scroll through the log records. The “Run Log” display can be accessed by simply selecting...
  • Page 161 The Run/Stop indicator shows whether the log entry indicates the time and date of a Run log entry or a Stop log entry. 9/29/09 System 824 Views 5-41...

  • Page 162: Time History

    Status Indicator- The Status Indicator will show one of the three possible events that occurred in the point of time referenced by the Time Cursor: Run - Indicates a measurement started at this time. Stop - Indicates a measurement stopped at this time. 5-42 824 Reference Manual 9/29/09...

  • Page 163: Single Other Level

    (S, F, I), RTA Spectra and even some non- acoustic parameters such as Wind/Tach data, Temperature (824 interior), External Voltage and Battery Voltage. Setting up for multiple other levels requires the use of the Advnc TH menu in the Time History menu. The selected parameters will be displayed in the same position as Lmax in the figure above.

  • Page 164: Intervals

    Intervals view display by selecting Intervals with Check key from within the main View menu. Intervals-a Display The Interval-a display consists of six major components: • Display label • Interval Number • Interval Date / Time 5-44 824 Reference Manual 9/29/09...
  • Page 165 Interval Date / Time - The Event Date/Time shows the time and date that this interval began. Reading - The L Reading shows the Leq for the currently displayed interval. SEL Reading - The SEL Reading shows the SEL for the currently displayed interval. 9/29/09 System 824 Views 5-45...

  • Page 166: Intervals-B Display

    The Interval Number indicates the order of the displayed interval in relation to the other interval records. Interval Date/Time - The Event Date/Time shows the time and date that this interval began. 5-46 824 Reference Manual 9/29/09...

  • Page 167: Intervals-C Display

    Display label Interval Number Interval Date/Time Lpeak - I Reading Lpeak - II Reading Interval Duration The following explains each of the display’s components: Display label - This shows the current display (for example, “Interval -c”). 9/29/09 System 824 Views 5-47...

  • Page 168: Intervals-D Display

    • Peak - I Exceedances • Peak - II Exceedances • Overloads The Interval-d display is shown below for the LOG and SSA instruments: Display label SPL Exceedances Interval Number Peak-I Exceedances Peak-II Exceedances Overloads 5-48 824 Reference Manual 9/29/09...

  • Page 169: Intervals-E Display

    Overloads - This shows how many overloads occurred during this interval. Intervals-e Display The Interval-e display consists of three major components: • Display label • Interval Number • Ln Centiles Readings The Interval-e display is shown below (LOG instrument only): 9/29/09 System 824 Views 5-49...

  • Page 170: Intervals-F Display

    The Interval-f display consists of seven major components: • Display label • Interval Number • Interval Date/Time • Average Windspeed • Maximum Windspeed • Direction of Maximum Windspeed • Interval Duration The Interval-f display is shown below (LOG instrument only) 5-50 824 Reference Manual 9/29/09...
  • Page 171 Direction of Maximum Windspeed - The Direction of Maximum Windspeed is the direction of the maximum instantaneous value of windspeed logged during this interval. Interval Duration - The Interval Duration shows the length of time of the currently displayed interval. 9/29/09 System 824 Views 5-51...

  • Page 172: Exceedance History

    You can access the Excd History Exceedance History Settings" on view display by selecting Excd History with the Check page 7-40. The System 824 Training key from within the main View menu. Manual, available from Larson Davis, is also an excellent reference.

  • Page 173: Excd-B Display

    Excd-b Display The Excd-b display consists of six major components: • Display label • Exceedance Number • Exceedance Date / Time • Peak - I Reading • Peak - II Reading 9/29/09 System 824 Views 5-53...

  • Page 174: Excd-C Display

    Maximum Reading - The Max Reading shows the maximum level recorded during this exceedance. Excd-c Display The Excd-c display consists of six major components: • Display label • Exceedance Number • Exceedance Date / Time 5-54 824 Reference Manual 9/29/09...

  • Page 175: Excd Time History Display

    Maximum Reading - The Max Reading shows the maximum level recorded during this exceedance. Excd Time History Display You have the option of recording a time history for each exceedance by setting “Excd Time-Hist” to “Yes” under the 9/29/09 System 824 Views 5-55...
  • Page 176 Level at cursor • Time at cursor • Current sample • Total number of samples • Total number of Excd records • Graph of Exceedance Time History The Excd Time History display is shown below: 5-56 824 Reference Manual 9/29/09...
  • Page 177 Current Sample - This is the current sample number as indicated by the cursor. Total Number of Samples -Shows the total number of samples taken for this exceedance. Total Number of Excd Records - Shows the total number of exceedances recorded. 9/29/09 System 824 Views 5-57...

  • Page 178: Daily Views

    The Daily-a display consists of 11 major components: • Display label • Record Number • Elapsed Time • Date • Leq Reading • LDN and CNEL Readings • Maximum and Minimum levels • Peak level The Daily-a display is shown below: 5-58 824 Reference Manual 9/29/09...
  • Page 179 The following explains each of the display’s components: Display label - This shows the current display (for example, “Daily-a”). If the 824 is started at 1900 hours, Record Number - Each “Daily” record is shown in the the first Daily record will run from order that it occurred.

  • Page 180: Daily-B Display

    Daily record in relation to the other records. A new daily record is created each new day. A day is defined as 12:00 midnight to 12:00 midnight. Date - Day, Date, month and year of the record 5-60 824 Reference Manual 9/29/09...

  • Page 181: Daily-C Wind Display

    Daily-c Wind Display The Daily-c Wind display consists of 10 major components: If the optional firmware 824-WND is • Display label not installed, the following message •...

  • Page 182: Daily-D Windy Percent Display

    5.04) and the percent of the time that the windspeed was above this level. Daily-d Windy Percent Display The Daily-d Windy Percent display consists of 4 major components: • Display label • Record Number • Date • Percent Windy Condition • Windy Directional Distribution 5-62 824 Reference Manual 9/29/09...

  • Page 183: Hourly Leq Display

    Windy Threshold Level of 5.04 (shown on the Daily-c View) were from the North West 68% of the time. Hourly Leq Display The Hourly Leq display consists of 7 major components: 9/29/09 System 824 Views 5-63...
  • Page 184 Daily record in relation to the other records. Hourly Leq Reading - This is the hourly Leq as shown by the cursor. Exceedance Leq - This shows the average level of all of the exceedance events. 5-64 824 Reference Manual 9/29/09...

  • Page 185: Metrics

    Metrics-a Display The Metrics-a display consists of five major components: • Display label • Reading • DNL Reading • CNEL Reading • Elapsed Time The Metrics-a display is shown below: 9/29/09 System 824 Views 5-65...

  • Page 186: Metrics-B Display

    22:00 and 07:00. Elapsed Time- This shows the elapsed time of the overall measurement. Metrics-b Display The Metrics-b display consists of six major components: • Display label • Reading • Exceedance • Background 5-66 824 Reference Manual 9/29/09...

  • Page 187: Passby

    Metrics, single 10dB passby event detected. The display can be PassBy, and Wind / Tach views. accessed by simply selecting PassBy with the Check key from within the main View menu. 9/29/09 System 824 Views 5-67...
  • Page 188 SEL Reading - This display shows the total sound energy of a measurement compressed into one second. Max Reading - This display shows the maximum sound pressure level that occurred during the passby. Date/Time -This displays the date and time of the passby. 5-68 824 Reference Manual 9/29/09...

  • Page 189: Wind/Tach

    The Wind-a display consists of five major components: • Display label • Sound Pressure Level • Windspeed • Wind Direction • Frequency of Windspeed Signal The Wind-a display is shown below: Display label Sound Pressure Level Frequency Windspeed Wind Direction 9/29/09 System 824 Views 5-69...

  • Page 190: Wind-B Display

    Display label • Live Wind Speed and Direction • Average Windspeed • Maximum Windspeed and Direction • Date/Time of Maximum Windspeed • Wind Exceedance Data • Windy Threshold Data The Wind-a display is shown below: 5-70 824 Reference Manual 9/29/09...

  • Page 191: Wind-C Percent Display

    Windy Threshold Level (in this instance 5.04) and the percent of the time that the windspeed was above this level. Wind-c Percent Display The Wind-c Percent display consists of three major components: 9/29/09 System 824 Views 5-71...
  • Page 192 Distribution is shown on a compass rose with indications of the percent of the time that windspeeds above the Windy Threshold Level were in the directions represented by each of the eight directional coordinates. In this instance we can 5-72 824 Reference Manual 9/29/09...
  • Page 193 Windy Threshold Level of 5.04 (shown on the Windy-b View) were from the North West 59% of the time. 9/29/09 System 824 Views 5-73...
  • Page 194 5-74 824 Reference Manual 9/29/09...

  • Page 195: Chapter 6 System 824 Virtual Instruments

    System 824 Virtual Instruments System 824 Virtual Instruments The System 824 presents a number of distinct “virtual instruments” enabling you to select the mode best suited to a particular application. You can, of course, create new setups for particular applications and add your own IDs to the System 824.
  • Page 196 . A snapshot history is provided to store and display data from the various modes. This chapter will discuss how to select an ID in addition to providing an explanation of the features of the currently available IDs. 824 Reference Manual 9/29/09...

  • Page 197: Selecting An Instrument Id

    Selecting an Instrument ID To select one of the System 824 instrument setups or IDs, do the following: There will be a ‘>’ to the left of the Step 1 Press the SETUP key. A menu similar to the currently enabled instrument ID. The...

  • Page 198: Ssa Measuring Ranges

    SSA Measuring Ranges By using a 24-bit DSP processor, the digital filters of the System 824 meets the specifications of IEC 61260 - Class 1 and ANSI S1.11-1986 Type 1-D over a linearity range exceeding 80 dB. The dynamic range of the analysis function, from noise floor to overload, is 85 dB (typical).

  • Page 199: Ln Percentiles (Spectral)

    It also displays spectra for the six Ln percentiles. AC/DC Output The AC/DC output on the 824 is through the 3.5mm stereo connector at the bottom of the instrument. This is a 2- channel output. A mono plug should NOT be used, it will short the “ring”...
  • Page 200 The two possible output signals are on the tip and the ring of the 3.5mm jack. The sleeve is ground. The selection in the 824 controls settings lists the signal output on the tip first, followed by the signal output on the ring. The AC output signal is always amplified or attenuated by the gain or attenuation selected for the instrument.

  • Page 201: Logging Slm

    Setup menu. This section covers some of the data acquisition features of the LOG instrument. Time History The System 824 Time History logs L readings and up to 37 additional parameters. The Time History graphical display allows you to scroll through the time history and Run/Stop events.

  • Page 202: Exceedances

    Average and maximum wind conditions (using external windspeed/direction transducers) Exceedances The 824 can log exceedance events based on sound levels that go over a predefined threshold. It can also be triggered by an event which raises the level by 10 dB. This is called a “Passby”...

  • Page 203: Sound Exposure

    Sound Exposure The System 824 lets you set the criteria level and criterion time for Dosimetry measurements. A 100% dose occurs if a person is exposed to a constant sound field with a SPL equal to the criterion level, for the criterion time or full dose hours.
  • Page 204 The LOG and ISM instruments have a dynamic range of 105 NOTE: Ranges are in dB SPL using a typical 377B41 microphone with 44.1 mV/Pa sensitivity. "RMS Measurement Range (LOG and ISM modes only)" on page C-11 for more 824 specifications. 6-10 824 Reference Manual 9/29/09...

  • Page 205: Chapter 7 Using Id Setting Files

    (ID). You can select one of the permanent ID’s or you can create your own library using the 824’s keypad or the 824 Utility soft- ware. This chapter will describe how to recall (or activate) an ID, customize it to suit your specific needs and then save it for later use.

  • Page 206: Customizing Settings

    This section gives an example of using the standard settings in the SSA instrument. The procedures in this example can be applied to the other Model 824 modes and instruments by simply substituting the other instruments’ specific settings for those of the SSA instrument.
  • Page 207 Check key. The SLM+RTA screen appears: The System 824 is now set to the SLM&RTA (SSA) instrument. Step 3 To access the Settings menu, press the Setup key.

  • Page 208: Settings Descriptions

    SLM+RTA view. Settings Descriptions Within the Edit Settings menu, use Descriptions of the System 824 instrument’s various settings keys to move are provided in this section. The following will be covered: from one setting to the next. Use •...

  • Page 209: Common Slm Settings

    “Logging SLM Define Report Settings” In the following sections, headings for each setting or display mode will identify in parentheses the particular System 824 instruments to which they pertain, as shown in the following example. Example: Title Setting - (SSA, LOG, ISM)

  • Page 210: Weighting Setting - (Ssa, Log, Ism)

    Menu, highlighting and selecting SLM, then Gain to obtain (see “Transducer”). the following Gain Menu. In the display, the lowest and highest levels that can be measured accurately are indicated by each live display’s graph scale. The following selections are available: 824 Reference Manual 9/29/09...

  • Page 211: Range Setting - (Log, Ism)

    NOTE: If Gain is set to -10 or -20 dB -20, -10, 0, +10, +20, +30, +40, +50 and the microphone type is not condenser then the gain is set to 0 dB Use the keys to highlight the desired value and the warning “Setting Conflict”...

  • Page 212: Transducer Setting - (Ssa, Log, Ism)

    NOTE: Using an electret microphone with the polarization voltage supplied being used is an air condenser type and the System with the “condnsr” option, will change 824 will generate the appropriate polarization microphones sensitivity voltage to make it function properly.

  • Page 213: Pk Weighting - (Ssa, Log, Ism)

    NOTE: Interval Spectral LNs will not be available when R.I. Correction is turned on. Overall Spectral LNs will only be available when the 824 is stopped. This means that the overall Spectral LN data will not be viewable when the 824 is running.

  • Page 214: Rta Weighting - (Ssa)

    Control settings are also available from some check menus as discussed later in this chapter.The Control settings are available on most System 824 instruments. The Control settings are available on most System 824 instruments. Control Settings - (ISM) For the ISM instrument, the control settings can be accessed through the “Edit Settings”...

  • Page 215: Control Settings

    Triggering for the SSA instrument is for Logic out only. If Logic-Out is set to “RMS”, the 824 looks at the level set under “SPL Excd Lvl 1”. See the section "LOG and SSA Triggering Settings" on page 7-23.

  • Page 216: Ac/Dc Output Settings - (Ssa, Log, Ism)

    E.A. Cal Tone Yes/No AC/DC Output Settings - (SSA, The AC/DC Output on the 824 allows the user to select what LOG, ISM) type of signal will be sent out the 3.5mm connector at the base of the instrument. See the section "AC/DC Output" on page 6-5 for more details.

  • Page 217: Logic Output Setting - (Ssa, Log, Ism)

    to +5 volt logic signal (input load impedance is 100K ohms). The resulting logical state (high or low) will determine what occurs inside the instrument as a function of this Logic Input setting. Accordingly, the setting provides the following five options: None - The state of the logic input pin has no effect.
  • Page 218 R+A - The Logic Output turns on when an RMS exceedance event occurs or when an event occurs on one of the A:D channels. 7-14 824 Reference Manual 9/29/09...

  • Page 219: Logic Output Time Setting - (Ssa, Log, Ism)

    P+A - The Logic Output turns on when a Peak exceedance event occurs or when an event occurs on one of the A:D channels. R+P+A - The Logic Output turns on when either an RMS or Peak exceedance event occurs or when an event occurs on one of the A:D channels.

  • Page 220: Logic Output #2

    Electrostatic Actuator (E. A.) of an outdoor microphone system. It is a CMOS output that drives from 0 to +5 volts through a 10,000 ohm current limiting resistor to pin 7 of the control connector; +5 volts is the asserted state. 7-16 824 Reference Manual 9/29/09...

  • Page 221: Logging Slm Twa Settings

    0 - 255 dB Crnt Criterion 0 - 255 dB Ovll Exchange - (LOG) This setting affects the System 824’s The Overall Exchange rate setting sets the exchange rate primary or overall memory buffer. (sometimes called the “doubling rate”) that is used to calculate the overall TWA.

  • Page 222: Ovll Threshold - (Log)

    RMS noise level. Ovll Threshold - (LOG) This setting affects the System 824’s The Ovll Threshold setting sets the threshold for computing primary or overall buffer. the overall time weighted average (TWA).

  • Page 223: Criterion Time - (Log)

    5dB may be added to the permissible exposure level every time the exposure duration is cut in half. This setting provides the following four options: This setting affects the System 824’s secondary or current buffer. 3dB - The Crnt Exchange defaults to the 3dB option.

  • Page 224: Crnt Threshold (Ssa, Ism, Log)

    Threshold setting is a submenu to the current time weighted average (TWA). SLM menu selection. This setting affects the System 824’s In compliance with the requirements of various regulatory secondary or current buffer. agencies, only those sound levels which are above a certain threshold level are used when computing the TWA.

  • Page 225: Enable Ln

    Use the keys to move The following is a table of the L settings: from one setting to the next. Then use key to change the selected Menu Items Available Settings Options setting. The key is used to return to previous menus. Enable Ln (SSA only) Start Level...

  • Page 226: Ln's

    “Intv Save Ln” to “Yes”. NOTE: If Random Corr. is set to [Yes] and Spectral Ln is set to [Interval] then Spectral Ln will be set to [None] and the warning “Setting Conflict” is displayed. 7-22 824 Reference Manual 9/29/09...

  • Page 227: Log And Ssa Triggering Settings

    LOG and SSA Triggering Settings For the SSA instrument, these Trigger levels can be set as follows: two for the SPL (RMS trigger settings are used to control value) and one each for Peak I and Peak II. These levels are the logic output line.

  • Page 228: Pk Excd Lvl 1 - (Log, Ssa)

    The event is triggered when a level goes over a corresponding trigger level, but does not become re-armed until the level drops below the value of the trigger level minus the hysteresis value. 7-24 824 Reference Manual 9/29/09...

  • Page 229: Log And Ssa Wind/Tach Settings

    Begin Trigger Hysteresis Time This setting can include any integer value within the following range: 0 to 9dB LOG and SSA Wind/Tach Settings Other transducers providing similar This feature is used most frequently with external weather pulse trains and DC voltages transducers providing an analog pulse train whose frequency representing measured parameters is proportional to windspeed and a DC voltage proportional...

  • Page 230: Setup Of Wind/Tach Function

    The Wind/Tach feature requires the optional firmware 824-WND. If it is not installed, attempting a setup will display the message shown to the right. Setup of Wind/Tach Function With either the LOG or SSA instrument active, press the SETUP key to access the “Edit Setup Menu”. Using the...

  • Page 231: Wind Scale

    Menu Items Available Settings Options Direction Unit Compass Degrees Percent Volts Number Wind/Tach Windy Threshold [nnn.n] or [nnnnn] Wind Excd Level [nnn.n] or [nnnnn] Windy Hysteresis [nnn.n] or [nnnnn] Windy Pause Enable Pulse Trigger Voltage Pulse Trigger Source Wind Scale Wind Scale is a scale factor which provides the wind speed (tach) when multiplied by the frequency of the wind speed (tach) signal from the external transducer.

  • Page 232: Wind Units

    0 to 100% as a percent of full throttle. Voltage Voltage reports this parameter as a DC voltage over the range 0 to 2.49 volts. Number Number reports this parameter in numeric form between 0 and 255.93 7-28 824 Reference Manual 9/29/09...

  • Page 233: Wind/Tach Enable

    These pseudo-sound signals are detected by the microphone, producing erroneous results. The System 824 can be set to pause sampling of the sound signal when the measured wind levels exceed this level. The instrument will also count the number of times the wind exceeds this level.

  • Page 234: Wind Pause Enable

    Wind Pause Enable Select Yes to enable the Wind Pause Function. This will cause the System 824 to pause sampling of the input signal whenever the wind speed is above the Wind Exceedance Level. Select No to disable this function.
  • Page 235 Use the keys to move The following tables show the Time History settings for the from one setting to the next. Then use LOG and SSA instruments. Each setting is described later in key to change the selected greater detail. setting.

  • Page 236: Hist Enable - (Log, Ssa)

    Marker 3 (Truck) Marker 4 (Train) Marker 5 (Animal) Hist Enable - (LOG, SSA) This setting provides the following two options: No - Time history storage is disabled. Yes - Time history storage is enabled. 7-32 824 Reference Manual 9/29/09...

  • Page 237: Hist Period (Log, Ssa)

    Hist Period (LOG, SSA) This setting is used in conjunction Hist Period sets the number of history period units that with the “Period Units Setting” transpire between successive time history samples. These (below). samples continue either until the instrument is stopped or runs out of memory.

  • Page 238: Resolution - (Log, Ssa)

    1.0dB - Leq and the optional Other Level are stored with 1.0dB resolution which requires only 1 byte per level stored. Levels are rounded to the nearest integer (85.5 would be stored as 86dB and 85.4 would be stored as 85dB). 7-34 824 Reference Manual 9/29/09...

  • Page 239: Advanced Time History - (Log, Ssa)

    Marker Text - (LOG, SSA) One of the features of the 824 is the ability to mark or annotate the SLM Time History as the instrument is running. This allows the user to identify each noise source as the measurement is being taken.

  • Page 240: Log And Ssa Interval Settings

    7-55 for a description of the Marker display. LOG and SSA Interval Settings Interval Settings are available on the The Intervals menu sets the System 824 to automatically LOG and SSA instruments. store at regular time periods, Leq, SEL, Lmax, Lmin, L , and the six Ln levels.

  • Page 241: Intv Enable - (Log, Ssa)

    Intv Auto Stop Intv Threshold 0 to 255 Intv Exchange Intv Spectrum None (SSA only) @Max Mins To store interval spectral Ln levels, set “Spectral Ln” to “Interval”, enable Ln and Interval histories and set “Intv Save Ln” to “Yes”. Intv Enable - (LOG, SSA) Intv Enable enables or disables the automatic storage of interval statistical records.

  • Page 242: Intv Save Ln's - (Log, Ssa)

    To start a new measurement after an automatic stop, just press the Run/Stop key. This setting provides the following two options: No - Disables the automatic stop feature. Yes - Enables the automatic stop feature. 7-38 824 Reference Manual 9/29/09...

  • Page 243: Intv Threshold - (Log, Ssa)

    Intv Threshold - (LOG, SSA) Intv Threshold sets the threshold for computing the interval time weighted average (TWA). As per the requirements of various regulatory agencies, only those sound levels which are above a certain threshold level are used when computing the TWA.

  • Page 244: Logging Slm Exceedance History Settings

    The Min Duration setting allows you to determine the minimum number of seconds an exceedance must last for it to be logged. This setting can take on any time value in the following range: 0-255 second 7-40 824 Reference Manual 9/29/09...

  • Page 245: Excd Time Hist - (Log)

    Excd Time Hist - (LOG) The Excd Time Hist setting enables you to indicate whether or not to have an Exceedance Time History saved as part of the exceedance. This setting provides the following two options: - The Exceedance Time History will be saved. - The Exceedance Time History will not be saved.

  • Page 246: Daily Enable - (Log)

    Daily History Settings are only The Model 824 automatically calculates daily sound available to the Logging SLM (LOG) statistics including: L 24, L , CNEL, L , Ln’s, peak uwpk instrument. , and L ; and for each hour of the day the hourly L...

  • Page 247: Data Report - (Log, Ssa)

    Use the keys to move The following is a table of the Define Report settings. Each from one setting to the next. Then use setting is described later in greater detail. key to change the selected setting. The key is used to Menu Items Available Settings Options return to previous menus.

  • Page 248: Spl Histogram - (Log)

    This setting provides the following three options: No - The interval report will not print. Short - The “short” interval report (including L , SEL, L , Pk-I, Pk-II, overloads, and exceedances) will print. 7-44 824 Reference Manual 9/29/09...

  • Page 249: Hist Report - (Log, Ssa)

    Long - The “long” interval report (including L , SEL, L , Pk-I, Pk-II, overloads, exceedances, and six Ln Percentiles) will print. Hist Report - (LOG, SSA) The Hist Report either enables or disables the printing of the Time history report. The history report contains the L , and optionally one selectable level (Lpk-I, Lpk-II, or Lmax) basic measurement parameter for each time history period.
  • Page 250 Detector Slow Fast Impl Weighting Gain Transducer Condnsr Elctret Direct Random Corr Pk Weighting RTA Detector Slow Fast RTA Weighting Bandwidth 7-46 824 Reference Manual 9/29/09...
  • Page 251 Intervals Intv Enable Intv Period hh:mm:ss Intv Time Sync Intv Save Ln’s Intv Auto Stop Intv Threshold 0 - 255 dB Intv Exchange Intv Spectrum None @Max 9/29/09 Using ID Setting Files 7-47...
  • Page 252 See the section "Advanced Time History - (LOG, SSA)" on page 7-35. Marker Text Marker 1 (Aircraft) Marker 2 (Automobile) Marker 3 (Truck) Marker 4 (Train) Marker 5 (Animal) 7-48 824 Reference Manual 9/29/09...
  • Page 253 Enable Start Level 0-99dB (default 15dB) Ln 1 Percent Selectable (default: 1.67%) Ln 2 Percent Selectable (default: 8.33%) Ln 3 Percent Selectable (default: 33.33%) Ln 4 Percent Selectable (default: 50%) Ln 5 Percent Selectable (default: 66.67%) Ln 6 Percent Selectable (default: 90%) Spectral LN None...

  • Page 254: Menu Layout Of Integrating Slm (Ism) Settings

    The Integrating SLM (ISM) Edit Settings menu has 16 configurable items. Provided in this section is a table depicting the menu layout of the ISM instrument’s Standard Settings. ISM Setting Menu Submenu Available Settings Items Options Title User customized text entry 7-50 824 Reference Manual 9/29/09...
  • Page 255 Detector Slow Fast Impl Weighting Range Normal High Transducer Condnsr Elctret Direct Random Corr Pk Weighting Crnt Exchange Crnt Threshold 0 - 255 dB Advanced See "Advanced Menu Layout" on page 7-56 9/29/09 Using ID Setting Files 7-51...

  • Page 256: Menu Layout Of Logging Slm Settings

    LOG instrument’s Standard Settings. LOG Settings Menu Items Submenu Available Settings Options Title User customized text entry Detector Slow Fast Impl Weighting Range Normal High Transducer Condnsr Elctret Direct Random Corr Pk Weighting 7-52 824 Reference Manual 9/29/09...
  • Page 257 Ovll Exchange Ovll Threshold 0 - 255 dB (default: 80dB) Ovll Criterion 0 - 255 dB (default: 90dB) Criterion Time 0 - 99 hours (default: 8 hours) Crnt Exchange Crnt Threshold 0 - 255 dB (default: 80dB) Crnt Criterion 0 - 255 dB (default: 90dB) Start Level 0 - 99dB (default 15dB) Ln 1 Percent...
  • Page 258 See "Advanced Time History - (LOG, SSA)" on page 7-35. Marker Text Marker 1 (Aircraft) Marker 2 (Automobile) Marker 3 (Truck) Marker 4 (Train) Marker 5 (Animal) 7-54 824 Reference Manual 9/29/09...
  • Page 259 Intervals Intv Enable Yes (default) Intv Period 0-24:0-60:0-60 (hh:mm:ss) Intv Time Sync Yes (default) Intv Save Ln’s Yes (default) Intv Auto Stop No (default) Intv Threshold 0 - 255 dB Intv Exchange 3dB (default) Excd History Triggering SPL Excd Lvl 1 SPL Excd Lvl 2 PK-1 Excd Lvl PK-2 Excd Lvl...

  • Page 260: Advanced Menu Layout

    Advanced Menu Layout Menu Submenu Available Settings Items Options Controls AC/DC Output AC-1 AC-2 (See also AC-1 DC "Control AC-2 DC Settings AC-2 AC-1 _(SSA, Logic-In Mode None LOG)" on Pause page 7-11) Toggle Level Alarm 7-56 824 Reference Manual 9/29/09...
  • Page 261 Menu Submenu Available Settings Items Options Controls Logic-Out (Continued) Peak Intv R+P+I R+P+A R+I+A P+I+A R+P+I+A Excd Logic-Out Time 0 - 255 sec Logic-Out #2 Peak Intv R+P+I R+P+A R+I+A P+I+A R+P+I+A Excd Logic-Out #2 Time 0 - 255 sec 9/29/09 Using ID Setting Files 7-57...
  • Page 262 Windy Threshold 0.0 - 65,535 Level firmware 824-WND Windy Exceedance 0.0 - 65,535 Level Windy Hystereses 0.0 - 65,535 Windy Pause Enable Pulse Trigger Voltage Pulse Source Define Data Report Report Setup Report 7-58 824 Reference Manual 9/29/09...

  • Page 263: Check Menus

    Check menu which is specific to the current display function. The Check menu is accessed simply by pressing the Check key from within the System 824’s different views. The available Check menu options vary between an instrument ID’s different views. The options available from each display allows the user to change settings peculiar to that display function.

  • Page 264: Check Menu Example

    Then use display, press the key to access the Check key to change the selected menu. A menu similar to the following appears: setting. The key is used to return to previous menus 7-60 824 Reference Manual 9/29/09...
  • Page 265 Step 2 Use the arrow keys to highlight Set- tings, then press the Check key or the arrow key. A menu similar to the following appears: Pressing the right arrow key Step 3 Use the arrow keys to highlight takes you to a different place than SLM, then press the Check key or the pressing the check...

  • Page 266: Slm Check Menu Options (Ssa And Log)

    The following screen appears when accessing the Check menu from the SLM view. Mark Display Pressing the right arrow key when “Mark” is highlighted puts you in the “Mark” display. The following screen appears: 7-62 824 Reference Manual 9/29/09...
  • Page 267 The “Mark” display shows the current SPL level and a time history of the SPL level is shown graphically. This enables you to set a marker in the time history. To set a marker in the time history, press the Check key.

  • Page 268: Graph Menu

    Check menu) allows you to graphically and interactively key allows you to adjust the adjust the Graph settings. A screen similar to the followings Graph Scale. When you are finished appears: customizing the settings of the graph, press the key to finish. 7-64 824 Reference Manual 9/29/09...

  • Page 269: Settings

    LOG display when pressing Check key from within the instrument. System 824 SSA instrument definition. Any Data Check Menu The following Check menu is accessible from the “Any Data” screen. Press the Check key and the following...

  • Page 270: Rta Check Menu

    Following is a chart of the check menu with a description of each menu item: Menu Items Purpose Enables switching between Tabular/ spectrum (graphical) view and Spectrum Tabular view. Modifies the SLM settings for the Settings selected instrument. 7-66 824 Reference Manual 9/29/09...

  • Page 271: Intervals Check Menu

    Changes scaling Graph instrument’s SLM history graph Selects either 1/1 or 1/3 octave Bandwidth filters. Intervals Check Menu The intervals displays have three different check menus depending upon which display you are viewing. When viewing the displays Interval-a through Interval-e the following menu appears after pressing the Check key: Following is a chart of the check menu with a description of...

  • Page 272: Time History Check Menu

    Changes the scaling of the “Leq Specta” graph Bandwidth Changes the filters to either 1/1 or 1/3 octave Time History Check Menu Press the Check key while viewing either of the Time History displays and the following check menus appear: 7-68 824 Reference Manual 9/29/09...

  • Page 273: Run Log Check Menu

    Following is a chart of the Time History check menu with a description of each menu item: Menu Items Purpose Broadband/ Allows you to view the broadband Spectrum history graph or the spectral data Locate Locates a specific time history record Settings Modifies the time history settings...

  • Page 274: Ln Centiles Check Menus

    Displays the Time History Ln Centiles Check Menus There are three different Check menus contained within the Ln Centiles views. Press the Check key while viewing the Ln Centile’s broadband displays and the following check menu appears: 7-70 824 Reference Manual 9/29/09...
  • Page 275 Following is a chart of the Ln Centiles broadband check menu with a description of each menu item: Menu Items Purpose Enable Ln Enables or disables Ln data Start Level Sets the minimum dB level to be calculated in the Ln data Ln 1 Percent Changes the percentage for Ln 1 Ln 2 Percent...
  • Page 276 Menu Items Purpose Settings Modifies the spectral Ln settings. (See table above, “spectral check menu items”, for a description of the settings) Graph Changes the scaling of the instrument’s spectrum graph. 7-72 824 Reference Manual 9/29/09...

  • Page 277: Other Logging (Log) Check Menus

    Other Logging (LOG) Check Menus See "SLM Check Menu Options (SSA This section presents the LOG instrument’s available Check and LOG)" on page 7-62 for a menus that are in addition to the SLM Check menu description of the (LOG) SLM check previously described in this chapter.

  • Page 278: Ln Centiles Check Menu

    Sets how long of an exposure time for the TWA level you can have before 100% dose occurs for the overall measurement. LN Centiles Check Menu The Ln Centile view has access to the following Check menu: 7-74 824 Reference Manual 9/29/09...

  • Page 279: Stats Check Menu

    Menu Items Purpose Settings Modifies the Ln percentiles settings for the selected instrument. Graph Changes scaling instrument’s Ln-b Centiles graph Stats Check Menu The Stats view has access to the following Check menu: Menu Items Purpose SPL Excd Lvl 1 Sets the lowest SPL trigger level.

  • Page 280: Time History Check Menu

    Graph Adjusts the scaling of the Time History graph Intervals Check Menu The Intervals view has access to the following Check menu: Menu Items Purpose Locate Locates an interval record Settings Modifies the Interval Settings. 7-76 824 Reference Manual 9/29/09...

  • Page 281: Excd History Check Menu

    Excd History Check Menu The Excd History displays have two different check menus depending upon which display you are viewing. When viewing the displays Excd-a through Excd-b the following menu appears after pressing the Check key: Following is a chart of the check menu with a description of each menu item: Menu Items Purpose...

  • Page 282: Daily History Check Menu

    Menu Items Purpose Hourly Data Displays hourly data First Displays the first hourly record Last Displays the last hourly record Find Displays a specific record Settings Modifies the Daily History settings 7-78 824 Reference Manual 9/29/09...
  • Page 283 In the “Hourly” display press the Check key and the following menu appears: Following is a chart of the “Hourly History” check menu with a description of each menu item: Menu Items Purpose Daily Data Displays Daily data First Displays the first hourly record Last Displays the last hourly record Find...
  • Page 284 7-80 824 Reference Manual 9/29/09...

  • Page 285: Chapter 8 Printing A Report

    C H A P T E R Printing a Report The System 824 allows you to print a report from data col- lected during a measurement. This chapter will discuss the following aspects of printing reports: • Connecting the 824 to a Serial Printer •...

  • Page 286: Printing Reports

    Step 3 Turn on your printer and the System 824. Printing Reports Step 1 Press the Data key and use the Recall Files menu to recall the measurement record that you want to print. You may not need to recall a file if you want to print something in memory that has not been stored.
  • Page 287 Recall Format Summary SSA, LOG Tailored All, short All, long None enabled Customize [allows you to select the print SSA, LOG, RTA options for an instrument ID and customize your reports - see the section on “Printing a Custom Report”] Print [prints the report] SSA, ISM, LOG,...
  • Page 288 Step 5 Your Report will now begin printing and the Sta- correspond to the Title setting you tus screen will appear. have configured in the Setup menu for the selected ID. Press the check key to abort the printing job. 824 Reference Manual 9/29/09...

  • Page 289: Defining And Printing Tailored Reports

    Defining and Printing Tailored Reports In the System 824, Tailored Reports With the System 824, a tailored report setting for each SSA are available to the SSA and LOG or LOG instrument ID can be created (i.e. each user can set instruments.
  • Page 290 Check key. The following screen appears: Step 4 Use the arrow keys to scroll through the available report settings. Use the Check key to select and change the options for each type of report. 824 Reference Manual 9/29/09...

  • Page 291: Using The Recall Format (Ssa And Log Instruments Only)

    Tailored item, then select it using the arrow described in "Connecting the 824 to key or the Check key and your “Tailored” a Serial Printer" on page 8-1 and report will begin printing.

  • Page 292: Default Settings Values For The Recall Format Reports

    This template shows the default settings for the Summary Report. The Summary Report includes the Data Report and the Log Report. After selecting the template, you can modify it as explained in "Printing a Custom Report" on page 8-23. 824 Reference Manual 9/29/09...
  • Page 293 Summary Report Template (SSA instrument) Lower Level Report Settings Report Settings Description Unformatted [No] A dump of all Read, Query and Interval remote commands. Multiple values are comma delimited. Data Report [Yes] This shows general information such as Leq, SEL, Dose, Projected Dose, Lmin, Lmax, Peak, Ln’s, exceedance, and calibration logs.
  • Page 294 You can customize the time history report by choosing the long or short report. Lowest Record (00000) Selects the lowest time history record to be printed. Highest Record (>99999) Selects the highest time history record to be printed. 8-10 824 Reference Manual 9/29/09...
  • Page 295 Summary Report Template (LOG instrument) Histograms SPL Histogram [No] You can customize the SPL Histogram report by choosing the long or short report. Lowest Level (045) Selects the lowest SPL histogram level to be printed. Highest Level (095) Selects the highest SPL histogram level to be printed. Resolution (5.0) Selects the SPL histogram resolution Pk-1 Histogram [No]...
  • Page 296 Highest Level (095) Selects the highest SPL histogram level to be printed. Resolution (5.0) Selects the SPL histogram resolution Pk-1 Histogram [No] You can customize the Peak1 Histogram report by choosing the long or short report. 8-12 824 Reference Manual 9/29/09...
  • Page 297 Tailored Report Template (SSA instrument) Histograms Lowest Level (110) Selects the lowest Peak1 histogram level to be printed. Highest Level (140) Selects the highest Peak1 histogram level to be printed. Resolution (5.0) Selects the Peak1 histogram resolution Pk-2 Histogram [No] You can customize the Peak2 Histogram report by choosing the long or short report.
  • Page 298 Report. The All, Short Report prints all of the reports. Those reports with a Short version are printed in the short form. After selecting the template you can modify it as explained in "Printing a Custom Report" on page 8-23. 8-14 824 Reference Manual 9/29/09...
  • Page 299 All, Short Report Template (SSA instrument) Lower Level Report Settings Report Settings Description Unformatted [No] A dump of all Read, Query and Interval remote commands. Multiple values are comma delimited. Data Report [Yes] This shows general information such as Leq, SEL, Dose, Projected Dose, Lmin, Lmax, Peak, Ln’s, exceedance, and calibration logs.
  • Page 300 You can customize the time history report by choosing the long or short report. Lowest Record (00000) Selects the lowest time history record to be printed. Highest Record (>99999) Selects the highest time history record to be printed. 8-16 824 Reference Manual 9/29/09...
  • Page 301 All, Short Report Template (LOG instrument) Histograms SPL Histogram [Yes] You can customize the SPL Histogram report by choosing the long or short report. Lowest Level (045) Selects the lowest SPL histogram level to be printed. Highest Level (095) Selects the highest SPL histogram level to be printed. Resolution (5.0) Selects the SPL histogram resolution Pk-1 Histogram [Yes]...
  • Page 302 Selects the Peak2 histogram resolution All, Long Report Template (LOG instrument) Lower Level Report Settings Report Settings Description Unformatted [No] A dump of all Read, Query and Interval remote commands. Multiple values are comma delimited. 8-18 824 Reference Manual 9/29/09...
  • Page 303 All, Long Report Template (LOG instrument) Data Report [Yes] This shows general information such as Leq, SEL, Dose, Projected Dose, Lmin, Lmax, Peak, Ln’s, exceedance, and calibration logs. Log Report [Yes] The run/stop log and with the date and time of each run/stop. Setup Report [Yes] Print the settings and their values for the LOG instrument.
  • Page 304 You can customize the time history report by choosing the long or short report. Lowest Record (00000) Selects the lowest time history record to be printed. Highest Record (>99999) Selects the highest time history record to be printed. 8-20 824 Reference Manual 9/29/09...
  • Page 305 None Enabled Report Template (SSA instrument) Histograms SPL Histogram [No] Prints SPL histogram and overall Spectral LN report. Lowest Level (045) Selects the lowest SPL histogram level to be printed. Highest Level (095) Selects the highest SPL histogram level to be printed. Resolution (5.0) Selects the SPL histogram resolution Pk-1 Histogram [No]...
  • Page 306 You can customize the Peak2 Histogram report by choosing the long or short report. Lowest Level (070) Selects the lowest Peak2 histogram level to be printed. Highest Level (120) Selects the highest Peak2 histogram level to be printed. Resolution (5.0) Selects the Peak2 histogram resolution 8-22 824 Reference Manual 9/29/09...

  • Page 307: Printing A Custom Report

    Customize menu screen, then use the described in "Connecting the 824 to row key to highlight the Print item, then select it a Serial Printer" on page 8-1 and using the Check key.
  • Page 308 Hist Report (No, Yes) -Lowest Record -Highest Record Histograms SPL Histogram (No, Yes) Lowest Level Highest Level Resolution Pk-1 Histogram (No, Yes) Lowest Level Highest Level Resolution Pk-2 Histogram (No, Yes) Lowest Level Highest Level Resolution 8-24 824 Reference Manual 9/29/09...
  • Page 309 The following table shows the available options under the Customize menu for the LOG instrument: Menu Items Options Unformatted Data Report Log Report Setup Report SPL Histogram Excd Report Short Long Intv Report Short Long Hist Report Daily Report 9/29/09 Printing a Report 8-25...
  • Page 310 Shows beginning and ending date and time, runtime, type of Averaging, sample rate, trigger phase ad Max Spectrum. Shows beginning and ending date and time, runtime, type of Averaging, sample rate, trigger phase ad Min Spectrum. 8-26 824 Reference Manual 9/29/09...
  • Page 311 (RTA instrument) Autostore Rpt The Short report prints the Leq, Lmax and Lmin spectrum. In addition, Short the ByTime Spectrums are included in the Long report. Long Lowest Record 0 - 65535 The lowest Autostore Record to print. Highest Record 0 - 65535 The highest Autostore Record to print.
  • Page 312 8-28 824 Reference Manual 9/29/09...

  • Page 313: Chapter 9 Performing A Sound Level Measurement

    A P P E N D I X Performing a Sound Level Measurement Due to the many features of the System 824 and the variety of measurements it is capable of performing, there is a great deal of instructive material in the preceding chapters. In this...

  • Page 314: Selecting A Measurement Id

    These data can be stored manually by the operator or automatically using the Time History and/or Interval methodologies. Details on the funtionality of each of these see “System 824 Virtual Instruments” on page 6-1. Select the desired measurement mode (ISM, LOG or SSA) as described in section ”Selecting and Modifying Instrument...

  • Page 315: Editing The Microphone Parameters

    Larson Davis recommends the following sound level calibrators: • Larson Davis Model CAL200; 94/114 dB @ 1 kHz • Larson Davis Model CAL250: 114 dB @ 250 Hz The procedure for performing a calibration is described in detail in section ”Turning On and Calibrating the System...

  • Page 316: Entering The Noise Floor Values

    Nominal Thermal Noise, dB(A) The procedure for entering the noise floor value for the microphone to be used is described in the section ”TTools Key” on page 3-18, subsection ”Calibration” on page 3-22 under the heading Noise Floor. 824 Reference Manual 9/29/09...

  • Page 317: Editing The Measurement Parameters

    Editing the Measurement Parameters The design of the System 824 permits the simultaneous NOTE: If recalling measurement ID which has already been measurement of the following sound level parameters, a configured for the measurement you wish feature we call “Any Data”: to perform, then you can skip to the next section.
  • Page 318 Measurement Time Secondary Parameter Frequency Weighting Although the System 824 measures the sound pressure level using multiple values of detector and frequency weighting, it only displays a single value as shown above. For this parameter, you have a choice of three detectors (averaging time) •...

  • Page 319: Positioning The Meter

    As a result, when performing measurements in the presence of low level airflows, it is recommended that a windscreen be placed over the microphone. Larson Davis provides the WS001 windscreen, a 3 1/2” diameter ball made of open cell foam 9/29/09...
  • Page 320 To install the windscreen, hold the meter in one hand and the windscreen in the other. Insert the microphone/preamplifier assembly into the opening in the windscreen as shown below and slide the windscreen completely down over the preamplifier. 824 Reference Manual 9/29/09...

  • Page 321: Selecting The Slm Display

    Selecting the SLM Display For sound level measurement, press the Vkey, use the ukey to highlight SLM and press the c key to obtain the display shown in ”Editing the Measurement Parameters” on page 9-5 Selecting the Measurement Range ISM and LOG Modes In the ISM mode, there are three range setting available: •...

  • Page 322: Selecting The Range Setting

    0 dB and later modify that as required to obtain a good measurement without overload or under range conditions. Although the gain setting does not usually appear on the SLM display, it can be found by repeatedly pressing either 9-10 824 Reference Manual 9/29/09...

  • Page 323: Performing A Measurement

    the uor dkey until the highlight is located in the lower right corner of the display as shown below. When the gain setting is highlighted, this can be changed by repeatedly presssing the uor dkey until the desired value of Gain appears. Performing a Measurement The procedure for performing a measurement is described in the section ”Performing a Measurement;...

  • Page 324: Averaging Time

    30 seconds be used. For timed measurements, the value of the averaging time can be preset and the instrument configured to stop automatically after that time as described in the section ”Measuring for a Preset Integration Time” on page 9-16. 9-12 824 Reference Manual 9/29/09...

  • Page 325: Linearity Range

    Linearity Range When making a measurement, the upper and lower linearity range limits of the instrument for the setting presently in effect are indicated by the dark regions with light numbers as indicated below. Upper Limit of Linearity Lower Limit of Linearity Range Changing the range (ISM and LOG Modes) or gain (SSA Mode will change these limits.

  • Page 326: Overload And Under Range Conditions

    ”Entering the Noise Floor Values” on page 9-4, in order for this feature to function correctly. 9-14 824 Reference Manual 9/29/09...

  • Page 327: Max, Min And Peak Values

    directed arrow in the upper right corner of the display as shown below. To avoid this condition, select a lower range (ISM or LOG Mode) are a higher value of Gain (SSA Mode). Max, Min and Peak Values As stated in ”Editing the Measurement Parameters” on page 9-5, Lmax and Lmin are measured for all combinations of frequency weighting (A, C and Flat) and detection (Slow, Fast and Impulse).

  • Page 328: Measuring For A Preset Integration Time

    Measuring for a Preset Integration Time The System 824 can perform an integrated measurement over a preset time in either the LOG or SSA Mode by making use of the Interval measurement feature. For a detailed description of setting up for an interval measurement, see the section ”LOG and SSA Interval...

  • Page 329: Measuring Using User-Selectable Thresholds

    Measuring using User-Selectable Thresholds The System 824 can be setup to measure data associated with Exceedance Events, defined as instances where the sound pressure level exceeds a user-selected threshold. For a detailed description of setting up the System 824 to measure Exceedance Events, see the section ”Logging SLM...
  • Page 330 9-18 824 Reference Manual 9/29/09...

  • Page 331: Chapter 10 Using The 824 Utility Software

    C H A P T E R Using the 824 Utility Software The 824 Utility software is a powerful tool for use with the System 824 from Larson Davis. This software will allow you to control, setup, download and translate your 824 measurement data quickly and easily.

  • Page 332: Starting The 824 Utility Software

    , press START and then select the Programs/Larson Davis/824Util menu item. Connecting to Your Computer To connect the 824 to a computer, use the CBL006 cable included with your System 824. The round 8-pin connector 10-2 824 Reference Manual 9/29/09...
  • Page 333 Serial port of the 824 and the 9-pin connector plugs into a serial port on your computer. You do not need to be connected to Before any functions can be performed on the 824, you must the 824 in order to translate files connect the 824 to the 824 Utility software.

  • Page 334: 824 Utility Tool Bar

    824. After a successful connection, the setup window will appear with a system setup in the setup list box. The 824’s serial number and title will be displayed on the setup dialog box screen.
  • Page 335 Create new setup button. This button will allow the user to create a new setup that can then be saved to disk, or saved in the 824. Open a setup from a computer file. This button will allow the user to retrieve previously stored setup files.

  • Page 336: 824 Utility Setup Window

    824 Utility program is started. The setup window will allow you to edit existing setups, retrieve setups from the 824 or a file, create new setups, and store setups to the 824 or to a file. The main setup window has 2 sections: the setup list box, and the settings dialog section.

  • Page 337: Retrieving Setups From The 824

    824 or a disk file. The settings dialog section will allow you to manipulate the setup. Setup List Box Settings Tab Dialog Retrieving setups from the 824 Setups stored in the 824 can be retrieved by clicking on the Get Setup button on the tool bar or by selecting Get Setups From 824 from the File Menu.
  • Page 338 Setups will be retrieved from the 824 and will be displayed in the Setup listbox. In the list of setup files, the system setup is the first setup and is followed by all of the permanent and user-defined set- ups. In the setup list box, there are several parts of the Setup title that can be used to identify the setup type.

  • Page 339: Modifying And Storing Setups To The 824

    Controls or Modem and then send the modified setup to the 824. To store the modified setup, select the Save Setup to 824 menu item from the File menu or click on the Store Setup in 824 button on the tool bar.

  • Page 340: Manipulating A Setup

    To change any of the variables for a particular user defined setup, select the setup. The appropriate setup tab dialog will appear at the right of the setup list box. Select the setting you wish to change and enter the new value. 10-10 824 Reference Manual 9/29/09...
  • Page 341 For example, it is not possible to delete a permanent 824 setup, so the Delete Setup menu item will be disabled if a permanent 824 setup is selected. The Rename Setup button allows you to rename the selected user defined setup.

  • Page 342: Saving Setups To Disk Files

    Select the Save Setup to a File menu item from the File menu or click on the Save to File button on the tool bar. The 824 Utility program will bring up a standard windows NOTE: The system...
  • Page 343 The setup appears in the Select Setup list box. You can then select (highlight) the desired setup in the list. The high- lighted setup can then be sent to the 824 by selecting the Save Setup to 824 menu item from the File menu.

  • Page 344: Creating A New Setup

    File menu or by selecting the New Setup but- ton on the tool bar. From the displayed dialog box, select the type of new setup. Press the OK button and you will now see the new setup in the Setup List box. 10-14 824 Reference Manual 9/29/09...

  • Page 345: Renaming An Existing Setup

    824. Renaming an Existing Setup To rename an existing user defined setup, right click on the setup in the left hand side of the screen and select Rename Setup from the popup menu. 9/29/09 Using the 824 Utility Software 10-15...

  • Page 346: Deleting An Existing Setup

    WARNING! The setup will be deleted from the 824 and the Utility pro- gram. 10-16 824 Reference Manual...

  • Page 347: Locking And Unlocking Setups

    Lock Setup from the popup menu. Note that if you have just created a new setup, the setup must first be stored to the 824 before it can be locked. Downloading Measurement Data...

  • Page 348: Specifying A Destination File

    You can also select “ALL <binary>” which will download all the files in the 824 simultaneously for translation at a later date. If you are selecting a specific file type such as “SSA” the measure- ment list box will show only SSA files.
  • Page 349 Select the destination directory you wish. was created as the file name as a default. It will also download the file to the 824 Utility Folder as a default. The option to specify a file name and destination folder is an optional selection, and is not necessary for download.

  • Page 350: Changing The Download File Name

    To change the name of the downloaded file, enter a new name in the “File name” area. Press the Save button to return to the download section of the 824 Utility software. Our new file name and the path to the...

  • Page 351: Adding Notes To A Download File

    Active Measurement on the tab of the download windows. The other measurements are stored as Data Files (on the 824), and will be reported as such on the tab of the download window. Active Measurement...

  • Page 352: Downloading The Measurement

    “setup” button on the toolbar. FFT, or RTA) only this file type will be listed in the mea- surement list box. Select one or more of the files and click the Download button. The following window will appear: 10-22 824 Reference Manual 9/29/09...
  • Page 353 Checking this box saves the binary file in the 824 Utility directory or the designated directory. Checking this box will launch a program associated with a.csv file or .txt file based on the radio box selection. For multiple file download, the first file will be loaded into the viewing program.

  • Page 354: Explanation Of Files In The 824 Utility Directory

    A downloaded file will be stored with If you only selected “Save Binary Data” the downloaded file the file extension slmdl (Sound Level must be translated by the 824 utility software to be viewable. Meter Down-load). The first file in the measurement list If you selected “Save Binary Data”...

  • Page 355: Translating Data From A Downloaded Binary File

    Translating Data from a Downloaded Binary File Selecting “Translate View” from the View Menu or pressing the Translate button on the tool bar will display the Transla- tion View. 9/29/09 Using the 824 Utility Software 10-25...
  • Page 356 Locate the folder that contains the downloaded file you wish to translate. In this case we have found the down- loaded file in the default location, C:\Program Files\Larson Davis\824 Utility. 10-26 824 Reference Manual 9/29/09...

  • Page 357: Selecting A Data Set To View

    Downloaded measurement file. Data translated from the Downloaded file. Selecting a Data set to view After the downloaded file is located, click on the data you wish to view. 9/29/09 Using the 824 Utility Software 10-27...
  • Page 358 The data is displayed on the right side of the screen. If the data record is too large to be effectively displayed in that area, a message will appear at the top of the displayed record indicating that it is available for export only. 10-28 824 Reference Manual 9/29/09...

  • Page 359: Printing A Translated File

    Printing a Translated File To print the translated data, select the file that you wish to print from the translate window . Display the file as described earlier. Select Print from the File menu. 9/29/09 Using the 824 Utility Software 10-29...
  • Page 360 The default Windows printer dialog box will be displayed. The report will be printed in a text format similar to that shown below. 10-30 824 Reference Manual 9/29/09...

  • Page 361: Viewing A Translated File Within A Spreadsheet Program

    File menu or the Launch Spreadsheet button on the tool bar. When you select the View Data in Spreadsheet menu item, the 824 utility program will attempt to launch the program associated with the .csv” file extension (comma separated variables). If you have installed a spreadsheet program, your Windows system will most likely have this file type linked to that spreadsheet program.

  • Page 362: Additional Features

    Additional Features Store Histograms for Overall and Interval Data One of the features of the 824 Utility software is the ability to store histograms in both the LOG and SSA virtual instru- ments for overall, interval, and daily data (LOG only).
  • Page 363 SSA or LOG instruments and also for the daily period data for the LOG instrument. NOTE: Storing the complete histogram for each interval and daily record greatly reduces the number of events that can be stored. 9/29/09 Using the 824 Utility Software 10-33...
  • Page 364 RT60 Select Options The 824 Utility software can calculate an RT60 for each 1/3 octave frequency from the autostore ByTime data taken by the RTA instrument. The software gives you the flexibility to set the options for the calculation and display of the RT60 values.
  • Page 365 824 uses logarithmic arithmetic to calculate the RT60 value and the 824 Utility software uses double precision to calculate the value, there may be small differences in the values as reported by the 824 instrument and by the 824 Utility software. 9/29/09...
  • Page 366 10-36 824 Reference Manual 9/29/09...

  • Page 367: Chapter 11 Rta (Optional)

    C H A P T E R RTA (optional) Welcome to the System 824 Real-Time Analysis Firmware Option. This option adds high speed spectral data gathering to the System 824 and will enable you to perform the following measurements: • Architectural Acoustics •...

  • Page 368: Settings Menu

    Minimum RT-60 Value The minimum RT-60 which can be measured, also referred to as the “Residual RT-60”, is a function of 1/3 octave response time as shown in the following graph. Re sid u al RT-60 11-2 824 Reference Manual 9/29/09...
  • Page 369 For other information pertaining to the RTA instrument, see the following in this manual: • For data storage, see "Taking Measurements and Storing Data" on page 4-5. • For printing RTA reports, see "Printing Reports" on page 8-2. • For I/O commands, see "Serial Port Interface Remote Control"...
  • Page 370 Exp Detc Time (seconds) 1/2 second Exp Store Rate 1/8 second Condnsr Transducer Electret Direct Random Corr Autostore Autostore Pretrigger # 0-400 samples Save ByTime Triggering Trigger Setup Any 1/1 or 1/3 octave filter Trigger Source Flat 11-4 824 Reference Manual 9/29/09...
  • Page 371 Menu Items Submenu Available Settings Options Available Settings Options L < Arm Mode L > Input Time Count Arm Level 0.0 - 255.9 dB Arm Time 00.0000 to 99.9975 sec Arm Samples 0 - 65535 Arm Logic In High L < Trigger Mode L >...

  • Page 372: Settings Descriptions

    Gain adjusts the voltage level delivered to the measuring portion of the meter from the microphone and preamplifier. Bandwidth Setting Selects 1/1 or 1/3 octave filter bandwidth for real-time analysis. Detector Setting Selects the averaging method to be used. • Linear 11-6 824 Reference Manual 9/29/09...
  • Page 373 • • NOTE: For example, if the detector time is 1/8 and the store rate is 1/2, then the 824 would generate spectra samples at a rate of 16 times per second. Transducer When a condenser microphone is •...

  • Page 374: Autostore Settings Menu

    Autostore Settings Menu Autostore When a linear detector is selected, Turns the Autostore function on or off. It allows the 824 to the store rate is that of the linear measure and store basic information such as the Leq, Max, detector.

  • Page 375: Arm Settings Menu

    This feature allows the user to enable or disable storage of records are automatically stored. ByTime data in an autostore record. With this feature turned off and the Autostore function turned on, the 824 will only store Leq, Max, and Min spectra. Triggering...
  • Page 376 • 0 - 65535 Arm Logic In When the “Arm Mode” is set to Input, the 824 will arm when the state of the Logic In line changes to this level. Logic In is sampled 32 times each second. •...

  • Page 377: Trigger Settings Menu

    This level is used when the “Trigger Mode” is set to Level specified by the Trigger Source (L<, L=, L>). This is the amplitude in dB at which the 824 setting. will start recording an Autostore record. It must be valid for the period of time set by “Trigger Time”.

  • Page 378: End Settings Menu

    • 00.0000 to 99.9975 seconds Trig Samples When the “Trigger Mode” is set to Count; “Trig Samples” is the number of samples that will be taken before the 824 starts recording an Autostore record. • 0 - 65535 Trig Logic In When the “Trigger Mode”...
  • Page 379 Samples” of data have been received. End Level This level is used when the “End Mode” is set to Level (L<, L=, L>). It is the amplitude in dB at which the 824 will stop recording an Autostore record. •...

  • Page 380: Then Settings Menu

    Then Settings Menu End Then After the measurement ends, the 824 may do the following: • Stop - The measurement ends. • Repeat - The measurement repeats when the Arm and Trigger settings have been satisfied. A new Autostore record is created for each repeated measurement.
  • Page 381 For more information on the Control Connector, see the section "System 824 Components" on page 1-10 The Heater control output is on pin 8 of the control connector and will conduct current to ground when asserted and not conduct when not asserted;...

  • Page 382: Rt60 Reverberation Time Settings

    An 8 character note field is provided to annotate a spatial incremented automatically with each average. This is useful when describing the measurement spatial average snapshot taken or you are taking and keeping track of different measurements stored. or their location. 11-16 824 Reference Manual 9/29/09...

  • Page 383: Rt60-A And Rt60-B Instrument Definition

    RT60-A and RT60-B Instrument Definition The RT60-A Setup is configured for The System 824 contains two special RTA IDs on the setup the use of a steady-state noise source menu which will simplify making an RT60 measurement. which is shut-off to initiate the Both of these setups load the RTA instrument but with the decay.

  • Page 384: Qualifying Background Noise: Rooms [Rta] Id

    Then: Stop Qualifying Background Noise: Rooms [RTA] ID This ID sets up the System 824 to The System 824 has an Instrument Definition that makes it measure and evaluate background easy to measure room criteria, NCB and RC, using the RTA noise according to the RC and NCB in 1/1 octave bandwidth.

  • Page 385: Display Views

    This next section will explain the various displays available under the View key. Once a measurement has been taken, the 824 allows you to view the results and manipulate the data. RTA Views The RTA Display Views are accessed through the View key.
  • Page 386 The live data current. If the sample time Live display is updated regularly when the 824 is running. is less than 0.25 seconds, the display still updates every 1/4 second.
  • Page 387 NOTE: Leq, Max, and Min are measured only while triggered, if triggering is enabled. If triggering is disabled they are measured while the 824 is running by pressing the R/S key. If Autostore is enabled, Leq, Max, and Min will be reset at every trigger (or run if Triggering is off), otherwise they will accumulate for each R/S measurement until manually reset.
  • Page 388 “OverAll” reset. The total running time is also displayed. This is the total elapsed time of all measurements since the previous “OverAll” reset. Display label Overall start date and time Overall end date and time Overall runtime 11-22 824 Reference Manual 9/29/09...

  • Page 389: Trigger Views

    Trigger Views The Trigger Display Views are accessed through the View key. To select the Trigger Display Views press the View key. The following menu will appear: Use the up and down arrow keys to highlight “Trigger”. Now press the right arrow key to bring up the “View Trigger”...
  • Page 390 Repeat measurement 2 times The interpretation of the Trigger Setup display is as follows: • The 824 will arm when the 1 kHz filter is greater than 80.0 dB for a period of 1 second. • When the level of the 1 kHz filter drops below 80.0 dB for 0 seconds (immediately), the 824 is triggered and begins taking a measurement.

  • Page 391: Autostore Views

    • The measurement will repeat 2 more times before stop- ping for a total of 3 measurements. As the settings are changed the Trigger Setup display will show the relevant settings in an easy to read form. Autostore Views If triggering is enabled, the record is An Autostore is a historical record of triggered data that is stored when the End condition is met stored automatically when the Autostore setting is set to Yes.
  • Page 392 Filter level in dB Bandwidth (1/1 or 1/3 oct.) Selected filter frequency Autostore duration Number of autostore records To move to the next Autostore display, press the check key and then the right arrow key. 11-26 824 Reference Manual 9/29/09...
  • Page 393 The Autostore Max display shows the maximum level obtained by each filter and the broadband maximum level of all samples while the Autostore is triggered. Autostore occurrence date and time Display label Record number/total records Filter level in dB Bandwidth (1/1 or 1/3 oct.) Selected filter frequency Autostore duration Number of autostore records...
  • Page 394 “ByTime” menu item and press the right arrow key to access the “ByTime” menu and displays. The following “View ByTime” menu appears: Press the check key to view the ByTime spectrums recorded during the Autostore. 11-28 824 Reference Manual 9/29/09...

  • Page 395: Autostore Bytime Spectral History

    Autostore ByTime Spectral History The Autostore ByTime spectral history has two displays for viewing the time history data. The first is called the ByTime Spectrum and the second is called the ByTime Graph. ByTime Spectrum The Autostore ByTime Spectrum display shows just one sample in time and the entire frequency spectrum with frequency on the horizontal axis.

  • Page 396: Bytime Spectrum Check Menu

    (toggling between the ByTime Spectrum view and the ByTime Graph view). Pressing the check key once when viewing the ByTime spectrum display puts you in the check menu. The check menu is shown below: 11-30 824 Reference Manual 9/29/09...

  • Page 397: Bytime Graph Check Menu

    Rooms display gives you the Hearing trum (for 1/1 octave filters) Threshold Level or HTL for this • Graph - Adjusts the graph scale and offset (See 824 Ref- spectrum. erence Manual) - Graph Level -Allows numerical entry of graph level in dB.
  • Page 398 - Find - Finds the specified ByTime record • Graph-V - Adjusts the vertical graph scale and offset - Graph Level -Allows numerical entry of graph level in dB. - Graph Scale - Allows numerical entry of graph scale 11-32 824 Reference Manual 9/29/09...

  • Page 399: Rt-60

    The horizontal graph adjustment, • Graph-H - Adjusts the horizontal graph scale (Graph-H), provides a useful feature that allows you to view a large amount of time data in the ByTime Graph view. A scale factor of 1 to 1024 can be selected.
  • Page 400 If auto RT60 is set to “Yes”, the Auto-select also sets the horizontal zoom so that the whole auto-select routine will be performed decay fits on screen. whenever a new filter is selected. 11-34 824 Reference Manual 9/29/09...

  • Page 401: Rt60 Check Menu

    RT60 Check Menu Pressing the check key when viewing the RT60 display puts you in the RT60 check menu. The check menu is shown below: The check menu offers the following options: • RT60 dB Down - dB down setting for RT-60 calculation •...
  • Page 402 Selected filter frequency Spatial averaged sample count *Annunciator or note Spatial averaged spectrum NOTE: *If the right digit of the annunciator is numeric then it will auto-increment with each spatial average store operation from the check menu. 11-36 824 Reference Manual 9/29/09...

  • Page 403: Spatial Avg Check Menu

    • Note- Note is used to describe this average which is to be stored to the Avg History The 824 will prompt you to reset the • Store - Store Spatial Average in Spatial Average History “Spatial Avg” buffer. This does not •...

  • Page 404: Avg History Check Menu

    To manipulate the “Avg History” records, press the check key to access the “Avg History” check menu. Avg History Check Menu The “Avg History” check menu is shown below: 11-38 824 Reference Manual 9/29/09...

  • Page 405: Rooms Views

    The check menu offers the following options: • Edit Note - Edit the note of this stored record. • Locate - Locate a Spatial Avg history record - First - The first Spatial Avg history record - Last - The last Spatial Average history record - Find - Finds the specified Spatial Average his- tory record If you are viewing an “Avg History”...
  • Page 406 NCB • Over - indicates that SIL is above the defined range for • (H) - indicates the NCB Hiss check failed • (R) - indicates the NCB Rumble check failed 11-40 824 Reference Manual 9/29/09...
  • Page 407 Rooms RC Use the up and down arrow The Rooms RC display calculates the noise criterion for the keys to move between the RC and spectrum being displayed when “Rooms” is chosen from a NCB displays. check menu. Display label Level in dB of selected filter Selected filter frequency Room midfrequency average level...
  • Page 408 The “HTL status” indicator can show the following: • Pass - indicates the recording environment is suitable to produce recordings without audible background noise • Fail - indicates the recording environment is NOT suit- able to produce recordings without audible background noise 11-42 824 Reference Manual 9/29/09...

  • Page 409: Chapter 12 Fft (Optional)

    C H A P T E R FFT (Optional) The FFT option gives the 824 the ability to do narrow band frequency analysis using the Fast Fourier Transform. This chapter describes the features and functions of this option. Features The FFT option has the following features: •...
  • Page 410 Gain (dB) Bandwidth (Hz) Avg Count 1 to 16384 Repeat Rectngl Window Hanning Flt-top Overload Skip Condnsr Transducer Elctret Direct Random Corr Linear Units 4 characters of text Linear Scale -128.99 to 127.99 Auto Snapshot 12-2 824 Reference Manual 9/29/09...

  • Page 411: Settings Descriptions

    Settings Descriptions Title Setting Use the title setting to create a title or heading for printed reports. This title will be placed at the top of each FFT report you print. You are allotted 30 characters. Printing of FFT reports is not currently available. Gain Setting -20 &...
  • Page 412 Avg Count The 824 FFT is guaranteed to have The average count is the number of FFTs taken and averaged no more than 75% overlap. together. • 1 to 16384 FFT Repeat Once the average count is completed you can choose to continue repeating the FFT or have the FFT stop.
  • Page 413 • Condenser - This indicates that the microphone being used, the 824 requires a stabilization used is an air condenser type and the 824 will generate time of approximately 45 seconds the appropriate polarization voltage. before a measurement can be taken.

  • Page 414: Fft Display

    With “FFT” highlighted, press the Check key to enter the spectrum and “Snapshot” displays FFT display. the FFT snapshot data. The FFT display shows a live FFT spectrum. Display label Level at cursor Selected filter frequency Count avg 12-6 824 Reference Manual 9/29/09...
  • Page 415 FFT Zoom You can view approximately 80 bars The FFT zoom on the 824 allows you to view a of the FFT at once. When you are representation of all 400 lines or a portion of the 400 lines on zoomed out you will notice that each the display.

  • Page 416: Fft Check Menu

    The check menu offers the following options: • Store Snapshot - Stores the current FFT spectrum at that moment in time. The THD as calculated in the 824 • THD - Activates the THD display which shows the satisfies all of the requirements for calculated THD.

  • Page 417: Thd (Total Harmonic Distortion)

    THD (Total Harmonic Distortion) The THD display shows the results of the THD calculations. Fundamental frequency THD+n percentile THD+n dB down Harmonic dB down Harmonic percentiles 4th & higher harmonic 4th & higher harmonic percentile THD information is only available Results are reported in dB down difference and units of on screen at the time of the percentile.

  • Page 418: Thd Check Menu

    “THD” display puts you in the check menu. The check menu is shown below: The check menu offers the following options: • View FFT - Takes you back to the FFT display 12-10 824 Reference Manual 9/29/09...

  • Page 419: Snapshot

    The bandwidth for each line is the • Bandwidth - Allows you to reduce the frequency bandwidth setting divided by the bandwidth from 20kHz to 200Hz. This setting provides lines setting. the following options: 200Hz, 500Hz, 1kHz, 2kHz, 5kHz, 10kHz, 20kHz Snapshot Once you have stored an FFT snapshot by accessing “Store Snapshot”...

  • Page 420: Snapshot Check Menu

    - Last - The last Snapshot record - Find - Finds the specified Snapshot record • Graph - Adjusts the graph scale and offset (See 824 Reference Manual) - Graph Level - Allows numerical entry of graph level in dB.

  • Page 421: Fft Calibration

    “level” implies a decibel value relative to a defined reference value. Acoustic measurements are in dB When the System 824 has been calibrated using an acoustic relative to 20 µPa calibrator, whether from the ISM, SSA, LOG or FFT instrument, the decibel levels are relative to 20 µPa (20 micro-Pascal).

  • Page 422: Displaying Amplitude In Linear Units

    When the linear scale is set to zero Linear Scale (dB) = 20Log (1 volt / sensitivity) the 824 will read the rms input voltage. Obtaining a readout in units of “g”. Example: The sensitivity of an accelerometer is typically provided in units of V/g.

  • Page 423: Setup Of Linear Units Readout

    The following table gives some examples of some typical Linear Scale values for common accelerometer sensitivities.: Sensitivity Linear Scale (dB) Units 100 mV/g 20 dB 50 mV/g 26 dB 25 mV/g 32 dB 10 mV/g 40 dB 5 mV/g 46 dB 14.0 mV/Pa 37.08 dB Pa (2540)
  • Page 424 Linear Units - This is the unit entered by the user in the menu for “Linear Units”. In this particular case we have entered “g” for acceleration. Frequency shown by cursor - This is the frequency as shown by the cursor. 12-16 824 Reference Manual 9/29/09...

  • Page 425: Frequently Asked Questions Concerning Fft

    ) and “G” for giga Frequently Asked Questions Concerning FFT What is the reference level for decibels (dB) levels in the FFT option of the 824? The decibel levels displayed by the FFT option of the 824 are the same as those for SPL in other instruments such as SSA or ISM and is 20 micro-Pascal (set during your microphone calibration process).
  • Page 426 How can I convert decibels (dB) levels from the FFT option of the 824 into linear units in my spreadsheet? There are two ways to calculate the linear units from decibels. Method 1: With the FFT instrument in the 824 the data can be outputted to the display in linear values such as 'g' (gravity), or meters/ second, volts or Pascal.
  • Page 427 0.5 volts RMS, the Linear Units setting is "g" and the Linear Scale setting is "-26.00" dB. I run the 824 FFT for a while and press stop, the display now shows a dB level of 121.7dB and a linear level of 50.87 milli-g.
  • Page 428 .005087g How can I manually enter a calibration offset so that the decibel levels (dB) from the FFT option of the 824 are relative to 1 micro-meter per second squared? The calibration offset is calculated with this formula (±5% accurate): LCAL = 20 log(4.467 nanovolts / Vref)
  • Page 429 1m/s2 outputs 0.01V then 1m m/s2 will have an output of 0.01mV). LCAL = 20 log(4.467 nV / 0.01mV) = 20 log(0.4467) = - 7.00dB LCAL is stored with these steps for instruments that have firmware version 4.065 or newer: Press the TOOLS key Highlight Calibration and press the right arrow key On the Calibration menu scroll to the bottom of the list and...
  • Page 430 LCAL value Command: "S 41,114"Response: ""// Restore Calibrator Level Here are typical Calibration Offset Levels (dB) for several accelerometer sensitivities (re. 1mm/s2): Sensitivity1mV/g10 mV/g100 mV/g1 V/g10 V/g Cal. Offset23.00 dB13.00 dB-7.00 dB-27.00 dB-47.00 dB 12-22 824 Reference Manual 9/29/09...

  • Page 431: Chapter 13 Aud (Optional)

    C H A P T E R AUD (Optional) The System 824 precision sound level meter with the 824- AUD firmware option is the heart of the Larson-Davis audi- ometer calibration system. This instrument and its firmware maintain and exceed the performance of previous Model 800B-based systems when used with the AUDit™...

  • Page 432: Connecting The Test System

    A microphone extension cable connects the microphone preamplifier to the input of the System 824. One of the audiometer earphones, connected to the audiometer via a cable (not visible here), is placed on top of the artificial ear and then the weight is placed on top to hold it firmly in place.

  • Page 433: Selecting The 824-Aud Operation Mode

    Selecting the 824-AUD Operation Mode To enable the 824 audiometer testing firmware option, turn on the 824. After the start screen is appears, press S SETUP and use the arrow keys up/down arrows ud to highlight the AudTest.AUD setup (or your customized AUD setup).

  • Page 434: Microphone Sensitivity Calibration

    “Change” and press the check key c. Follow the prompts to perform the calibration.. Please refer to the 824 Reference Manual for information on calibrating the instrument. AUD Modes There are three measurement modes for the AUD instrument: ⎯...

  • Page 435: View Menu

    ⎯ • Pulse/FM used to measure pulse and frequency modulation functions of the audiometer. The mode is controlled by the display being shown. The View menu is divided into three sections for the three modes and can be used to select the display needed for a particular measurement.

  • Page 436: Display Sequence

    VIEW key V to obtain the display shown below. Then select the SLM/RTA with the up/down arrows ud and press the check key c. This will produce the SLM+RTA Live Display shown below. The right and left arrow keys control the filter cursor. 13-6 824 Reference Manual 9/29/09...

  • Page 437: Slm+Rta Live Check Menu

    The check menu (accessed by pressing the check key c while this display is active) provides the setting choices shown in the next two screen shots. SLM+RTA Live Check Menu The SLM+RTA Live check menu items are: • Graph -Allows control over the resolution and scaling of the spectrum graph.

  • Page 438: Any Level -A, -B And -C Displays

    "Linearity RTA varying the hearing level output and monitoring the Display" on page 13-10, "Linearity measured level on the 824. FFT Display" on page 13-14and "Flatness FFT Display" on page 13- Similarly, cross talk measurements are performed with the non-test earphone being measured, then comparing the test earphone level to that measurement.

  • Page 439: Any Level Check Menu

    The Any Level -c display, shown below, displays the Slow SPL, Leq and SEL for the selected frequency weightings and the peak level with its frequency weighting. Use the right and left arrow keys to step between the -a, -b and -c displays.

  • Page 440: Linearity Rta Display

    This will open the Linearity RTA check menu, shown below. Highlight “Set Reference” and press the check key c again. The reference can also be set to an absolute level using the "Reference Lvl" setting on the check menu. 13-10 824 Reference Manual 9/29/09...
  • Page 441 Once the reference has been set the level is shown relative to the reference level as shown below. This display is used to measure the attenuator linearity of an audiometer. The highest amplitude fractional octave RTA bin is found and displayed in the lower left corner of the display.

  • Page 442: Manual Lock

    When above the trigger level the filter frequency will track the highest amplitude signal. When the level of that filter drops below the trigger level the lock is activated and the filter 13-12 824 Reference Manual 9/29/09...

  • Page 443: Linearity Rta Check Menu

    frequency is unchanged. The icons will show this condition with the lock and diamond icons as shown below. Auto-Lock Note: To change to another filter in auto mode, just increase the amplitude until the level is above the trigger level. When in automatic mode the Automatic Gain Control will be activated.

  • Page 444: Linearity Fft Display

    The chosen reference level is displayed in the lower right corner. A precise measurement of the frequency is displayed to the center right of the display. If the level is greater than the 13-14 824 Reference Manual 9/29/09...
  • Page 445 trigger level setting the THD plus noise value will be displayed in the upper right corner. To set the reference level to the current level first press the check key c to display the check menu shown below. Then highlight "Set Reference" and press the check key c once more.

  • Page 446: Manual Lock

    When the gain is set to 0dB, it will be changed to +30dB when the signal is more than 45dB below the overload level for 1.5 seconds. When the gain is set to 13-16 824 Reference Manual 9/29/09...

  • Page 447: Linearity Fft Check Menu

    +30dB, the gain will be changed to 0dB whenever the instrument becomes overloaded or the level is within 8dB of the overload level for 1.5 seconds. The instrument will beep once when the gain is changed automatically to 0dB and twice when it is automatically changed to +30dB.

  • Page 448: Flatness Fft Display

    THD plus noise value will be displayed in the upper right corner. The example display shown above is for a measurement at 1kHz. Measurements at 8kHz and 125Hz would appear as shown below. 13-18 824 Reference Manual 9/29/09...

  • Page 449: Thd Display

    The FFT capabilities of the 824 are used to measure the fundamental level, fundamental frequency and harmonics. THD data is output in dB down from the fundamental level and in percent. The display also shows the level and frequency of the fundamental.
  • Page 450 The THD as calculated in the 824 For THD to be calculated, the following criteria must be satisfies all of the requirements for met: ANSI S3.6.

  • Page 451: Pulse/Fm Display

    • If a harmonic is less than 10 dB above the noise floor, the level of the harmonic is marked with an asterisk. The noise floor is calculated as the maximum of the minimum in the two adjacent valleys. • If one of the harmonic’s side-bands is higher than the harmonic then the harmonic is marked with an asterisk.

  • Page 452: Pulse/Fm-A Display

    20 and 50 ms • Fall Time (E-G) - time in milliseconds between the -1 dB point and -20 dB point on the falling edge of the pulsed signal envelope, nominally between 20 and 50 ms 13-22 824 Reference Manual 9/29/09...
  • Page 453 • On Time (J-K) - time in milliseconds between successive -5 dB points of the envelope of the pulsed signal during which the signal is present, nominally between 190 and 260 ms • Off Time (F-J)) - time in milliseconds between successive -5 dB points of the envelope of the pulsed signal during which the signal is absent, nominally between 190 and 260 ms...

  • Page 454: Pulse/Fm-B Display

    • Minimum frequency • Modulation rate Pulse/FM Check Menu While in either the Pulse/FM-a screen or Pulse/FM-b screen the check menu can be accessed by pressing the check key This menu contains the following items. 13-24 824 Reference Manual 9/29/09...

  • Page 455: Fft Display

    • Gain -Changes the gain setting of the instrument. Generally use 0dB gain for levels at 70dB SPL and above, and 30dB gain for levels less than 70dB SPL. • High Pass Wght -This setting enables the high pass filter section of the A or C weight filters which provide low frequency noise reduction while measuring pulses or FM signals;...
  • Page 456 Note also that the FFT's A and C weighting filters may have up to ±0.2dB variation compared to the FFT Flat weighting (due to component variations and tolerance). To make absolute or flat weighted measurements, ensure that the Weighting setting is set to Flat. 13-26 824 Reference Manual 9/29/09...

  • Page 457: Appendix A Serial Port Interface Remote Control

    A P P E N D I X Serial Port Interface Remote Control The System 824 is fully controllable remotely via the Serial Port interface. Settings and the operational mode can be changed by sending commands through the serial port. Data can also be downloaded to and settings queried and set by the controlling computer.

  • Page 458: Interface Cables

    The System 824 may be connected to the computer directly or through a modem. network many instruments can be formed, all controlled by one computer by using the address-ability mode. This chapter will describe the Serial Port interfacing of the System 824 and the various interface commands with their syntax.

  • Page 459: Connection To A Computer Using Cbl006

    ® ® Apple Macintosh computers. CBL006 824 to computer cable (9 pin female ‘D’) CBL002 824 to serial printer (25-pin male ‘D’) CBL003 824 to modem cable (25 pin male ‘D’) CBL091 824 to HP LaserJet (9 pin male ‘D’)
  • Page 460 Both versions work properly with the Model 824. 824 Reference Manual 9/29/09...

  • Page 461: Daisy Chain Addressing

    ‘Daisy Chain Addressing following instruments compatible on a common network: Models 712, 720, 812, 814, 824, 870, and TAC100. Future instruments may also be compatible with this network. A network of instruments may be interconnected to one computer using the appropriate cabling, and each may be controlled individually.

  • Page 462: 824 Network, Addressing Commands

    Address 125 ($FD), Lock, will lock the current addressing of all 824s on the net so that binary setting data may be sent to the currently addressed 824. To cancel the lock so that addressing may be changed a <break> is sent.
  • Page 463 Address 124 ($FC), Auto ID, will initiate an Auto-Identification of all 824s on the net using a timing scheme based on each unit's address. The data received will be the address byte from every device on the net delayed by 10mS times the address;...

  • Page 464: Commands

    Commands Symbol Mode Commands Read Commands Settings Commands History Oriented Commands E, I, D, L, C, H, T Print Commands Error Messages & Warnings Commands Modem Control Commands Miscellaneous Commands (unsupported) Key Simulation Commands 824 Reference Manual 9/29/09...

  • Page 465: Remote Control Commands (Detailed

    Format for the Mode Commands is: Command Description Power On (clear error message list and reset display functions to “–a” windows) Power Off (cease sending further commands or the 824 will power back on) Run (begin accumulating data) Stop (stop accumulating data) M4,1...

  • Page 466: Read" Commands (Reads Out Data Variables

    Enable High Resolution Levels (nnn.nn for all sound level data (to I/O channel)) M 10 Lock 824 (leaves 824’s power on) M 11 Lock 824 and Power Off (cease sending further commands) M 12 Disconnect Modem (terminate connection and hang up) M 13...
  • Page 467 Example: “F3 E0 M3” means there is a 1/3 octave filter installed, there is no ENV option, and the memory is the standard 2 megabytes. R1,2 Read Model string “824” R1,3 Read Flash Identification “hhhh” Manf/Device Code (IF IF 13...
  • Page 468 The fifth character will be an “a” if an Alarm has been detected, otherwise it will be a space. • The sixth character is the modified status of the active setup (ID), space for unmodified and “A” for archive. A-12 824 Reference Manual 9/29/09...
  • Page 469 R3,3 Status of Active ID Archive Status, “A” indicates that it has been modified since being uploaded. Changed Status, “C” indicates that it has been changed and not saved back to it’s ID from file, “F” indicates that it has been recalled from a data file.
  • Page 470 SSA, ISM, Current UWPk Date and Time ddmmmyy hh:mm:ss OverAll RMS Exceedances #1 nnnnn OverAll RMS Exceedances #2 nnnnn OverAll Peak Exceedances nnnnn R 34 OverAll UWPk Exceedances nnnnn Overloads nnnnn Number of PAUSES nnnnn A-14 824 Reference Manual 9/29/09...
  • Page 471 PAUSE Time (OFF Time not inc.) hhhhh:mm:ss LOG, SSA Ln 1 nnn.n dB LOG, SSA Ln 2 nnn.n dB R 40 LOG, SSA Ln 3 nnn.n dB R 41 LOG, SSA Ln 4 nnn.n dB LOG, SSA Ln 5 nnn.n dB LOG, SSA Ln 6 nnn.n dB...
  • Page 472 R98,n Error Message List (n= 1 to 8) cccccccccccccccccccccc n = 1 to the last error. If n=0 or omitted then the 8 error codes are output as number. (nnn, nnn, . . . nnn). A-16 824 Reference Manual 9/29/09...
  • Page 473 Logic Output 1 State [On/Off} R100 Logic Output 2 State [On/Off} R101 Report Number nnnnn R102 Page Number nnnnn R103 Printer Line Number R104 Calibration Date/Time ddmmmyy hh:mm:ss R105 Cal Check Date/Time ddmmmyy hh:mm:ss R106 Cal Offset nnn.n R107 Cal check Level nnn.n + OFFSET R108 SSA, ISM, LOG...
  • Page 474 W - Watchdog Reset An indicator has been added to the ON display on the top line of the 824’s display to show faults that were detected by the power on test procedure. The R151 command will display the fault character to a computer.
  • Page 475 R154 Internal UwPk detector level nnn.nn dB R155 Number of Bytes in Keyboard Stack This is used with keyboard simulation to prevent the loss of keys. R156 Background Leq Time hhhhh:mm:ss.ss R157 Calibration Status Done, Wait, Waiting, Stable, Unstable, Too High, Too Low.
  • Page 476 RTA filter - CURRENT Leq nnn.n dB *f is ANSI filter R173,f SSA, TAL RTA filter - OVERALL Leq nnn.n dB *f is ANSI filter R174,f SSA, LOG, RTA filter selected frequency cccccHz RTA, AUD, *f is ANSI filter A-20 824 Reference Manual 9/29/09...
  • Page 477 R175 OverAll End Date and Time ddmmmyy hh:mm:ss R176 Current End Date and Time ddmmmyy hh:mm:ss R177 OverAll Reset/Began Text “Reset” or “Began” R178 Current Reset/Began Text “Reset” or “Began” R179 Total bytes of RAM installed in the nnnnnnn R180 Current Instrument Type R181 Number of Data File Records...
  • Page 478 -1 for Flat) R215 Trigger State ‘Stop, Ready, Armed, Trigd, Ended’ R216 Pre-Trigger Samples R217 Triggered ByTime Samples R218, n Triggering String (,n) 1&2=ARM, character string 3&4=Trig, 5&6=End, 7=Repeat 21 character string, 0=all strings A-22 824 Reference Manual 9/29/09...
  • Page 479 R219,f Spatial Averaged Spectrum nnn.n (f=ANSI filter number or -1 for Flat) R220 Spatial Averaged sample count nnnnnk R221,f Room Spectrum (f=ANSI filter nnn.n number or -1 for Flat) R222,f Room Class Spectrum (f=ANSI fil- nnn.n ter number or -1 for Flat) R223 Room Level, SIL or Lmf in dB nnn.n...
  • Page 480 ‘n’, n=1 to 20 R241, AUD, FFT Show distortion of harmonic levels n.nn % n+512 ‘n’ and above R241, AUD, FFT Show distortion of harmonic ‘n’, -nnn.n dB n+768 and above minus fundamental level, n=1 to 20 A-24 824 Reference Manual 9/29/09...

  • Page 481: Any Data" Read Commands

    *If f=0 then all 33 filter levels will be output in a comma delimited string. **If n=0 then all 6 percentages will be output in a comma “ANY DATA” READ COMMANDS The 824 measures SPL data with three frequency weightings and with three time weighting detectors...
  • Page 482 R 26,w SSA, ISM, LOG Current Lpk Date (Any Wght) ddmmmyy hh:mm:ss and Time R163,x SSA, ISM, LOG TAKT 3 (Any Wght/ nnn.n dB Dect) R164,x SSA, ISM, LOG TAKT5 (Any Wght/ nnn.n dB Dect) A-26 824 Reference Manual 9/29/09...
  • Page 483 Where “x” indicates a number to represent combination weighting and detector which has these values: A weight, Slow detector A weight, Fast detector A weight, Impl detector C weight, Slow detector C weight, Fast detector C weight, Impl detector Flat weight, Slow detector Flat weight, Fast detector Flat weight, Impl detector If “x”...

  • Page 484: Other Read Commands

    Other read commands are macro commands that send multiple “R” variables, so multiple data can be retrieved from the 824 with one command. Other commands O 1, O 2, and O 4 are preprogrammed macros while O 3 is a user-defined macro which is programmed by the Group command.

  • Page 485: Group Read Programming

    Code Description Response AUD, FFT Read THD data: Fund. Frequency, Fund Level, THD+n, 2nd, 3rd, 4th, 5th and above. nnnnnn, nnn.n, n.nn,n.nn,n.nn,n.nn AUD, FFT Read Fund. Frequency and Fund. Level nnnnnn, nnn.n Group Read Programming The group command permits the programming of a user-defined macro with up to eight (8) Read variables.

  • Page 486: Setting Commands

    Character e.g. (Gas Flare, Test 1); can be up to 30 char- queried (Q). The setting numbers acters provided below in the “Setting List” section are for both the Set (S) and • Template e.g. (hh:mm:ss) Query (Q) commands. A-30 824 Reference Manual 9/29/09...

  • Page 487: Querying Settings

    Brackets indicate optional characters or operands. <cr> = carriage return; <lf> = line feed; _ = space Querying Settings The current setting is retrieved with the Query (Q) command. The syntax query command Q[uery ]setting_number[,options] where setting_number is the number of the desired setting and options is a number to select the appearance of the response.
  • Page 488 Flag values may be added together for desired combinations: Example: Response 1.Q74 2.Q74, 1 Excd History Enable=No 3.Q74, 2 [_No] 4.Q74, 32 5.Q74, 3 Excd History Enable=[_No] A-32 824 Reference Manual 9/29/09...

  • Page 489: Ln Query Commands (Ssa

    Responses are denoted by (x) if Yes/ No or (n) if numerical. Ln Query Commands (SSA) Commands Instru- Description Comments ment Type Q 63 Ln 1 Percent nn.nn Q 64 Ln 2 Percent nn.nn Q 65 Ln 3 Percent nn.nn Q 66 Ln 4 Percent nn.nn...
  • Page 490 Option settings text must include the same number of characters that are given when queried, including spaces, which are indicated below with “__”. Syntax Response S[et]item_number; [option_text] <cr><lf> Example: S9; [_9600] sets Baud Rate to 9600. A-34 824 Reference Manual 9/29/09...

  • Page 491: Numeric Settings

    Example: S74; [Yes] sets Excd History Enable to Yes. Example: S95; [_1/32s] sets Hist Period Units to 1/32s Example: S95; [_1.0s] sets Hist Period Units to 1.0s Numeric Settings Syntax Response S[et]item_number, setting_value <cr><lf> Example: S62, 120 sets RMS Excd Level 2 to 120. Character String Settings To include leading spaces in a character string setting, precede the...

  • Page 492: Template Settings

    “:”. (24 hour clock time is used: i.e. hours 0 to 23. Syntax Response S[et]item_number; hh:mm:ss <cr><lf> Example: S30, 09:25:00 sets Timer Run Time 1 to 09:25:00. Example: S6, 23:05:33 sets current time to 23:05:33 (11:05:33pm) A-36 824 Reference Manual 9/29/09...

  • Page 493: Setting List

    Setting List Com- Instrument Description Comment mand Type S1,x RESET-ALL S2,c HEADING LINE #1 S3,c HEADING LINE #2 S4,c HEADING LINE #3 S5,c MEASUREMENT TITLE S6,t CURRENT TIME S7,t CURRENT DATE S8,x DAY OF WEEK S9,x Serial Communications Baud Rate S10,n Serial Communications Address S11,x...
  • Page 494 TIMER RUN TIME1 SSA, LOG TIMER STOP TIME 1 SSA, LOG TIMER RUN TIME 2 SSA, LOG TIMER STOP TIME 2 LOCK COMBINATION LOCK R/S KEY LOCK SETUP LOCK FUNCTION LOCK RESET LOCK THE ‘ON’ KEY A-38 824 Reference Manual 9/29/09...
  • Page 495 LOCK I/O CAL LEVEL CALIBRATOR S/N AUTO-CALIBRATION MODE AUTO CAL TIME SSA, ISM, DETECTOR LOG, AUD SSA, ISM, FREQUENCY WEIGHTING LOG, AUD AC/DC Output Control [AC-1 AC-2 | AC-1 DC | AC-2 DC | AC-2 AC-1] SSA, ISM, Pk Detector Weighting [A | C | Flat] LOG, AUD SSA, ISM, RANGE [Normal | Low | High]...
  • Page 496 Lnn 1 PERCENT RTAf TRIGGER SOURCE LEVEL [12.5, 16.0 . . . 16.0K, 20.0K, FLAT] Hz. Lnn 2 PERCENT RTAf ARM MODE [NOW, L<, L=, L>, INPUT, TIME, COUNT] Lnn 3 PERCENT RTAf ARM LEVEL (NNN.N) dB A-40 824 Reference Manual 9/29/09...
  • Page 497 Lnn 4 PERCENT RTAf ARM TIME (SS.SSSS) SECONDS (FOR LEVEL AND TIME ARM MODE CONDI- TIONS) Lnn 5 PERCENT RTAf ARM SAMPLES (NNNN) Lnn 6 PERCENT RTAf ARM LOGIC INPUT TRUE [LOW, HIGH] LEVEL SSA, ISM, SPL Exceedance Level 1 RTAf TRIGGER MODE [NOW, L<, L=, L>, INPUT, TIME, COUNT]...
  • Page 498 (NNN) O TO 255 TIMES SSA, LOG ENABLE INTV HISTORY RTAf AVERAGE COUNT (N) 0 TO 9 TIMES SSA, LOG INTV EXCHANGE RATE RTAf ANNUNCIATOR (CCCCCCCC) IF RIGHT DIGIT IS NUMERIC IT WILL AUTO-INCRE- MENT SSA, LOG INTV THRESHOLD A-42 824 Reference Manual 9/29/09...
  • Page 499 RTAf RT-60 CALCULATION dB [5, 10, 20, 30] DOWN SETTING SSA, LOG INTV PERIOD HORIZONTAL GRAPH SCALING [1, 2, 3, 4, 6, 8, 11, 16, 23, 32, 45, 64, 90, 128, 181, 256, 362, 512, 724, 1024] SSA, LOG INTV TIME SYNC INTV SAVE Ln’S SSA, LOG INTV AUTO STOP...

  • Page 500: Histogram Reports

    PEAK-II HISTOGRAM TABLE S109 PEAK-II HISTOGRAM TABLE LOW VALUE S110 PEAK-II HISTOGRAM TABLE HI VALUE S111 PEAK-II HISTOGRAM TABLE RESOL S112 PEAK-I HISTOGRAM TABLE S113 PEAK-I HISTOGRAM TABLE LOW VALUE S114 PEAK-I HISTOGRAM TABLE HI VALUE A-44 824 Reference Manual 9/29/09...

  • Page 501: Tailored Report

    S115 PEAK-I HISTOGRAM TABLE RESOL Tailored Report S116 EXCD REPORT S117 SSA, ISM, INTV REPORT S118 HIST REPORT S119 DAILY NOISE REPORT S120-142 Reserved settings Miscellaneous S143 Audiometric Calibrator Mode [SLM/ RTA | FFT | Pulse/FM] S144 FFT Lines [100 | 200 | 400] S145 AUD, FFT FFT Bandwidth [200 to 20KHz]...
  • Page 502 R/S AND CAL LOG S179 SETUP REPORT S180 RMS HISTOGRAM TABLE S181 RMS HISTOGRAM TABLE LOW- EST VALUE S182 RMS HISTOGRAM TABLE HIGH- EST VALUE S183 RMS HISTOGRAM TABLE RESO- LUTION S184 PEAK-II HISTOGRAM TABLE A-46 824 Reference Manual 9/29/09...
  • Page 503 S185 PEAK-II HISTOGRAM TABLE LOWEST VALUE S186 PEAK-II HISTOGRAM TABLE HIGHEST VALUE S187 PEAK-II HISTOGRAM TABLE RESOL S188 PEAK-I HISTOGRAM TABLE S188 RTAf PRINT LIVE SUMMARY OR [NO, YES] EVENT DATA S189 PEAK-I HISTOGRAM TABLE LOW VALUE S189 RTAf PRINT LEQ SUMMARY OR [NO, YES] EVENT DATA S190...

  • Page 504: Error Checking I/O

    • To disable error checking two <CR> characters in a row may be sent (if not in the Modem Mode) or the S205, 0F command is sent. A-48 824 Reference Manual 9/29/09...
  • Page 505 10dB of the noise floor. It is also used with NF Compensate, Q208, which will place the System 824 in an extended Linearity Range Mode. The true noise floor of the entire system must be measured and entered in Q207.
  • Page 506 BIAS OFFSET - For High Range Cali- bration (uses 225.48 lock) S231 Reserved setting S232 Temperature Calibration (Cal level must be 225.48) S233 SERIAL NUMBER Entry (secured set- ting) S234 Model Number Entry (secured setting) S235 Invalid Setting’s data block A-50 824 Reference Manual 9/29/09...

  • Page 507: Rta Settings Commands

    RTA Settings Commands Filter Bandwidth [1/1 | 1/3] Detector [Lin | Exp] Time Weighting Linear Detector Time (ss.ssss) seconds Exponential Detector Time [1/64 | 1/32 | 1/16 | ... 32 | 64] Exponential Detector Sample Rate [1/2 | 1/8] Auto-Store Records [No | Yes] Event By-Time Pretrigger Samples (nnn) Event Triggering Enable [No | Yes]...
  • Page 508 10 | 20 | 30] Horizontal Graph Scaling [1, 2, 3, 4 ... , 725, 1024] S188 Print Live Summary or Event Data [No | Yes] S189 Print Leq Summary or Event Data [No | Yes] A-52 824 Reference Manual 9/29/09...
  • Page 509 S190 Print Max Summary or Event Data [No | Yes] S191 Print Min Summary or Event Data [No | Yes] S192 Event working report enable [No | Short | Long] S199 Event ByTime REPORT LOWEST nnnnn RECORD S200 Event ByTime REPORT HIGHEST nnnnn RECORD S213...

  • Page 510: History Records

    Backup, and Find commands (see below) or the Setting S211 through S217. The various histories of the System 824 are each accessed in a similar fashion. The Find command is the primary method of locating a history record for random (nonsequential) access.

  • Page 511: Types Of History

    number is an alternate form of the Find command. Brackets in the syntax indicate optional characters and operands. <cr> = carriage return; <lf> = line feed Types of History Each history is assigned a number (history_number) so that it can be identified explicitly with...

  • Page 512: Backup

    Backup current history by 5 records Example: B9,5 Backup the calibration history by 9 records from the current calibration history Find Find record number directly. Syntax Response F[ind]num_record[, history_number] <cr><lf> Example: F9,5 Locates calibration history record 9 A-56 824 Reference Manual 9/29/09...

  • Page 513: History Data Variables

    Generally Find command to get to the first record (F1,2) and the Advance command (A) to move up through the records. History Data Variables Exceedance History Variables Brackets in the syntax indicate optional characters and operands. Syntax Response E[xceedance]var_no Excd_var Example: E9 __2 (Overload count from current record) Commands...
  • Page 514 E17,n Extracts ByTime History and returns nothing E18[n] Excd Time-History nnn.n dB RT60 delta time. NOTE: Value is determined by prior E 16, or E E19<,n> Excd T.H. Time -sss.ss E20<,n> Excd T.H. Number -nnn A-58 824 Reference Manual 9/29/09...

  • Page 515: Interval History Variables ("I" Commands

    Commands Instrument Description Commnet Type E21<,n> Excd T.H. Bargraph ********************* E101 Excd Macro Variables 1-10, 25 Macro E102 Excd Macro Time-Hist 17, 18... Macro Interval History Variables (“I” Commands) The Interval History is a long- duration time history of statistical data.
  • Page 516 Commands Instrument Description Comments Type I0, I101 or variable greater that 4 will run macro by default. SSA, LOG, Date and Time of Occurrence ddmmmyy hh:mm:ss RTA, FFT, SSA, LOG, Duration hh:mm:ss / mm:ss.ss A-60 824 Reference Manual 9/29/09...
  • Page 517 Commands Instrument Description Comments Type Number of Samples Averaged nnnn Count SSA, LOG nnn.n dB Spectral or Flat Level (n=ANSI nnn.n dB filter#) OVER LOAD cccc Overload Counts SSA, LOG nnn.n dB Note Field cccccccc Overall Level nnn.n Mode [SLM | RTA | Tonal] SSA, LOG Lmin nnn.n dB...
  • Page 518 “I” Commands for Basic SLM Mode: Commands Instrument Description Comments Type I5,n SSA, LOG Any SPL; n=1 to 9 nnn.n I6,n SSA, LOG Any Max; n=1 to 9 nnn.n I7,n SSA, LOG Any Leq; n=1 to 9 nnn.n A-62 824 Reference Manual 9/29/09...
  • Page 519 Commands Instrument Description Comments Type SSA, LOG LAFTM5 (Takt5 A Fast) nnn.n SSA, LOG Intv Impulse A Leq (dB) nnn.n SSA, LOG Intv Ln 1 Percent SSA, LOG Intv Ln 1 Level (dB) nnn.n SSA, LOG Intv Ln 2 Percent SSA, LOG Intv Ln 2 Level (dB) nnn.n...

  • Page 520: Daily History Variables - (D1-D102

    Daily Lmin nnn.n dB Daily Lmax nnn.n dB Daily Lpeak nnn.n dB D 10 Daily Luwpk nnn.n dB D 11 Daily Run Time hh:mm:ss | mm:ss.ss D 19 Daily Ln Table in hexadecimal hhhhhh, hhhhhh,...hhhhhh <ih> A-64 824 Reference Manual 9/29/09...

  • Page 521: Run Log Variables (Ssa, Ism, Log, Tal

    D 20 Intv Ln 1 Percent D 21 Intv Ln 1 Level (dB) nnn.n D 22 Intv Ln 2 Percent D 23 Intv Ln 2 Level (dB) nnn.n D 24 Intv Ln 3 Percent D 25 Intv Ln 3Level (dB) nnn.n D 26 Intv Ln 4 Percent...

  • Page 522: Calibration History Variables (Log

    Brackets in the syntax indicate optional characters. Syntax Response C[alibration]var_no cal_var Example: C1 114.0 (checked level) Checked Level nnn.n Day, Date and Time ddd ddmmmyyyy hh:mm:ss Calibration Mode [Manual/Auto] Cal Status [OK/Bad] C 101 Cal Variables 1-4 Macro A-66 824 Reference Manual 9/29/09...

  • Page 523: Time History Variables (Ssa, Log, Tal

    Time History Variables (SSA, LOG, TAL) Brackets in the syntax indicate optional characters and operands. SSA, LOG, Leq (RMS Level) nnn.n dB Other level (Pk-I, Pk-II, or Lmax) nnn.n If Other Level is set to Advc then “___” SSA, LOG, Run time of sample hhhhh:mm/hh:mm:ss/mm:ss.ss SSA, LOG,...

  • Page 524: Histogram Table Variables

    Run Time of Sample (calc) hhhhh:mm/hh:mm:ss/mm:ss.ss HISTORY BARGRAPH ==========----- Histogram Table Variables Brackets in the syntax indicate optional characters and operands. Table: • 1=RMS, • 2=Peak, • 3=Unweighted Peak. Default is last used table or RMS. Syntax Response A-68 824 Reference Manual 9/29/09...

  • Page 525: Print Command

    T[able]var_no[, table] table_var Example: T1,1 -75.0 (RMS current bin level) T 1 [n Level of current bin nnn.n dB T 2 [n] Count of samples nnnnnc (c= K or M for Kilo or Mega) T 3 [n] Percent of total nnn.nn% T 5 [ n] Prints the accumulated time for the...
  • Page 526 Begin Printing through current I/O command channel (See X100 Com- LOG, RTA mand) P 101 ISM, SSA, Begin Printing through channel selected by “Print Command” LOG, RTA P 999 ISM, SSA, Abort Printing LOG, RTA A-70 824 Reference Manual 9/29/09...

  • Page 527: Error Messages And Warnings

    Also use this to download reports for printing on a computer’s printer, rather than directly from the 824; this lets reports to be printed on a nice laser printer connected to a computer without having to disconnect it from the computer.
  • Page 528 “Timer Pending” “Printer is Busy” “DPC Format” “Key No Effect” “Stop Required” “Setting Wrong” “Overall Reset Required” “OPEN #” “Already Open” “No History Yet” “At End of History” “At Start of History” “History Format Bad” A-72 824 Reference Manual 9/29/09...
  • Page 529 “EEPROM Fault” “Out of Memory” “Memory was Lost” “Unimplemented” “System Locked” “A:D Stack Full” “A:D Over-Run” “Serial Port Framing” “Serial Port Line Noisy” “Serial Port Over-Run” “Unknown I/O Command” “Operand 1 Range” “Operand 2 Range” “I/O Overflow” “Can’t Calibrate” “Calibration Invalid” “Analog Calibration Bad”: often an indication of a faulty EPRM “ID is Active”...

  • Page 530: Modem Control Mode (All Instruments

    Dial Out Mode defined below. Dial Out Mode • None: The Model 824 will not dial a computer for any reason. • Excd: The Model 824 will dial a computer to report when an illegal exceedance is logged into memory. An illegal exceedance is when Excd Lmax >...

  • Page 531: Monitor Number

    The Model 824 dialing process is as Step 1 The Model 824 recognizes an exceedance or low follows: memory condition. Example: 824 sends: ATDT 1- Step 2 The Model 824 asks the modem to dial the phone number. 555-1234(Enter) Modem sends:...

  • Page 532: Model 824 Answering Procedure

    Step 2 The Model 824 answers the phone. Step 3 The modem informs the Model 824 that a connec- Modem sends: 824A0123:001:0 tion has been made. The Model 824 modifies its baud rate to that of the connected modem.
  • Page 533 Computer sends: Step 5 The Model 824 awaits a response code, which 824A0123:11111111 should be: “824A0123:11111111” (enter), where (0123) is the Model 824’s serial number and...

  • Page 534: Unsupported Miscellaneous Commands

    The advantages of the binary features can be obtained by utilizing Larson•Davis soft- ware (turnkey application, data translators or function library support is available). ^X^X CANcel transfer mode, 2 in a row (ASCII <CAN> or CHR$(24)). >a,b Read 824's memory from address (a) and bank (b) A-78 824 Reference Manual 9/29/09...

  • Page 535: Data File Commands

    Read Excd T.H. Buffer. This command is used to create an SPL vs. Time plot that is time cohesive. Resolution is, by default, 1 dB with one byte/sample being sent. Each byte has 32 added to it to avoid confusion with ASCII control codes, subtract 32 to use. Only the samples taken since the last read are sent, up to the buffer size of 128 samples.

  • Page 536: Keyboard Simulation

    Recall a FILE into active memory &F103 Store the current data (in active memory) to a FILE Keyboard Simulation The keys on the 824’s keyboard may be simulated with the ‘K’ I/O command. Each key is given an ASCII character as shown in the table below.

  • Page 537: Operation Notes

    When using the Logic Input line in the ‘LEVEL’ mode both I/O and keyboard Runs and Stops are inhibited. If the line is High the 824 takes data and if the line is Low no data is taken. The ‘Pause’ mode will pause the data taking process while the line is high;...
  • Page 538 A-82 824 Reference Manual 9/29/09...

  • Page 539: Appendix B Integrated Level Calculations

    A P P E N D I X Integrated Level Calculations Basic Integrated Level Calculations The Larson Davis System 824 calculates all of its integrated levels based on equations from IEC standard 804. IEC-804 Section 3.3 defines L eq as follows:...
  • Page 540 If no frequency weighting is used, the quantity is simply called equivalent continuous sound pressure level. The Larson Davis System 824 calculates many time-inte- grated levels or time-weighted averages (TWA) based on different parameters and time intervals. They are all...
  • Page 541 The actual measurement time is also provided for each TWA value to fulfil the time interval description requirements. For example, the System 824’s Logging SLM Overall-a dis- play shows the current SPL (Sound Pressure Level) in 1/ 10 th decibel (dB) resolution. The actual real-time resolution is 1/32 nd dB.
  • Page 542 The limit of s is 4,294,967,295 samples and is stored in a 32 bit integer variable within the System 824. This limit is greater than 1553 days or greater than 4 years and 4 months.
  • Page 543 SEL Calculations SEL is available for both the overall and current measure- ments and is calculated using this formula: ⎛ ⎞ s ( ) ------- - ⎜ ⎟ ∑ • – ⎜ ⎟ ⎝ ⎠ Since the sample rate is 32 samples per second and SEL is based on time in seconds, the log(32) is subtracted from the log of the accumulation to perform a division by 32.
  • Page 544 ⎠ DOSE k is the exchange rate constant which is equal to: 10.00 for an exchange rate of 3dB (L , or Ý 3dB/log(2)) 13.29 for an exchange rate of 4dB (L , or = 4dB/log(2)) 824 Reference Manual 9/29/09...
  • Page 545 32 samples per second, is the criterion sound duration as set by the System 824’s “Criterion Time Hours” setting which by default is set to 8...
  • Page 546 824 Reference Manual 9/29/09...

  • Page 547: Technical Specifications

    Technical Specifications The specifications contained in this chapter are subject to change without notice. Please refer to calibration and test results for data on a specific unit. These specifications are valid for all System 824’s using the NOTE: Where possible, tests...

  • Page 548: Declaration Of Conformity

    Declaration of Conformity Larson Davis Inc. declares that: Model 824 Sound Level Meter and Realtime Analyzer having been tested in representative configuration with: PRM902 preamplifier, 377B41 microphone and the following cables: EXA010 microphone extension cable, CBL042 AC/DC output cable, CBL006 serial interface cable is in accordance with the following directives: •...

  • Page 549: General Specifications

    System 824 Main Characteristics: NOTE: The 824 does not meet IEC 61672-1, IEC60804 or ANSI S1.4 Class 1 Precision Integrating Sound Level Meter with real-time specifications when used with a high 1/3 Octave Filters, classified as group X for the emission of,...
  • Page 550 Calibration procedure: Using a Larson-Davis CAL200 or equivalent calibrator, insert the microphone fully into the calibrator. Set the calibrator to 114 dB SPL. On the 824 press the tools key, arrow down to “Calibration” and press the right arrow key.
  • Page 551 AC/DC Output AC output voltage ±3 Volts peak range: DC output voltage 0 to +3 Volts range: SPL Start level – ------------------------------------------- - 0.028 × ------ - Vo 0.028 Start level AC/DC output ~600 Ohms, AC ouput error: <0.1 dB for input impedance: impedances >...
  • Page 552 (e.g. Ray-O-Vac I-C3 15-minute charging time) Memory Retention Memory retention without batteries or 5 minutes minimum external power Physical Characteristics Length: 9.9 inches 25.1 cm Width: 3.4 inches 8.6 cm Depth: 1.6 inches 4.0 cm Weight: 18 oz 0.51 kg 824 Reference Manual 9/29/09...
  • Page 553 Resolution Levels: 0.1dB (0.01 dB via I/O) Dose: 0.01% Elapsed time: Highspeed RTA, as rapid as every 2.5 mS all other instruments, 0.1 second Real time clock 1 second Calendar: 01 Jan 2000 - 31 Dec 2099 Cable Drive Capability (with PRM902 preamp) Frequencies to 20 kHz: 700 feet 213 meters...
  • Page 554 ∞ 16000 15850.00 -6.6 -8.5 1.0, -3.0 2.0, ∞ 20000 19950.00 -9.3 -11.2 1.0, -4.0 2.0, * Flat frequency response for SSA instrument is extended at the low frequency end when Random Incidence Correction is enabled. 824 Reference Manual 9/29/09...
  • Page 555 Infrasonic Frequency Response 824 Infrasound Response Frequency (Hz) 1000 10.0 20.0 30.0 40.0 50.0 LOG and ISM Mode Specifications Time weighting: Slow, Fast, Impulse, TWA and Peak Frequency Weightings A, C and Flat (see table on page C-7) Dynamic range: >...
  • Page 556 Flat AC output with 30 Weighted DC output dB gain AC-2 AC-1 Flat AC output with 30 Flat AC output dB gain NOTE: In low range, all AC outputs will provide an additional 20 dB of gain C-10 824 Reference Manual 9/29/09...
  • Page 557 RMS Measurement Range (LOG and ISM modes only) Electrical High Range Pulse Noise Floor Limit Limit Range A-WT (high) < 22 < 43 > 108 > 108 A-WT (normal) < 12 < 23 > 108 > 108 A-WT (low) < 10 <...
  • Page 558 < 33 dBA typical with PRM902, 377B41 microphone, and 0 dB gain Reference level range: 0 dB gain Exchange rates: 3, 4, 5, or 6 dB Sample rate: 51,200 Hz 1/3 octave band 12.5 Hz - 20 kHz frequencies: C-12 824 Reference Manual 9/29/09...
  • Page 559 Filter type: Digital Octave frequency Base 2 (See IEC ratio: 61260 Annex A) AC/DC Output (SSA mode only) 824 Menu 3.5mm Connector Tip 3.5 mm Connector Ring AC-1 AC-2 Flat AC output C-weighted AC output AC-1 DC Flat AC output...
  • Page 560 Time resolution: 0.5 ms to 1.0 seconds in 0.5 ms increments Time accuracy: ±1.0 ms Hilbert transform < 0.1 dB magnitude error: Dynamic range: > 80 dB Hilbert transform 2000 Hz Sample rate: C-14 824 Reference Manual 9/29/09...
  • Page 561 2 seconds, the 824 will revert to looking for the pulse rise time. FM Modulation Tests The FM modulation test code computes the minimum and maximum periods of the input waveform. The minimum and maximum frequencies are the inverse of the average of the last 8 periods.
  • Page 562 Rectangular or Hanning Linearity range: >85 dB with Hanning window, 20 kHz bandwidth, and PRM902 Dynamic range: >100 dB Flat SPL linearity range: >75 dB Highpass frequency vs. filter bandwdth for 824 FFT Bandwidth Hz/Bin -0.2 dB 20,000 50.00 10,000 25.00 5,000 12.50...
  • Page 563 Typical response of AUD A-weight and C-weight high pass filters Frequency Weightings Nominal Exact Flat A Weight C Weight Freq. Freq. 10.00 -72.6 -14.5 12.5 12.59 -65.5 -11.4 15.85 -58.8 -8.6 19.95 -52.5 -6.3 25.12 -46.8 -4.5 31.5 31.62 -41.5 -3.1 39.81 -36.6...
  • Page 564 ≥ 75 dB Anti-aliasing: ≤ ±1.0 dB (±0.4 typical) Summation of output signals: Flat frequency 10 Hz - 20 kHz, relative response: attenuation <±0.15 dB Filter type: Digital Octave frequency ratio: Base 2 C-18 824 Reference Manual 9/29/09...
  • Page 565 AC/DC output: AC out 1 is flat weighted and follows the gain (tip); AC out 2 is C-weighted with 0 dB gain (ring) Measurement range: Flat is measured to ANSI S1.4 and IEC 60651 standards for SLM linearity. 1/3 and 1/1 octave filters are measured to IEC 1260 standard for Class 0...

  • Page 566: 1/1 And 1/3 Octave Filters

    IEC 61260:1995 Class 1. 1000 Hz Passband IEC Class 1 Limits 125.00 120.00 115.00 0.85 0.95 1.05 1.15 Relative Frequency Figure 13-2 Passband of 1kHz 1/3 Octave Filter C-20 824 Reference Manual 9/29/09...
  • Page 567 130.00 1000 Hz Filter Skirts IEC Class 1 Limits 120.00 110.00 100.00 90.00 80.00 70.00 60.00 50.00 40.00 30.00 20.00 10.00 Relative Frequency Figure 13-3 Filter Skirts of 1kHz 1/3 Octave Filter 9/29/09 C -21...
  • Page 568 When using the 824, the meter is held in one hand with the arm extended away from the body. Better results can be obtained by using a tripod.
  • Page 569 Windscreen Response with Respect to No Windscreen 9/29/09 C -23...

  • Page 570: Frequency Response

    Frequency Response Random Incidence Microphone Correction When random incidence correction is turned on in the 824, a digital filter is added which gives the necessary correction to provide random incidence response when measuring with a free-field microphone. NOTE: Tested with the preamplifier...
  • Page 571 Graph 1 - The 824 in normal range with the 2540 free-field microphone showing the uncorrected random response. Graph 2 - The 824 in normal range with the 2540 free-field microphone showing the corrected random response. 9/29/09 C -25...
  • Page 572 Graph 3 - The 824 in normal range with the 377B41 free- field microphone showing the uncorrected random response. Graph 4 - The 824 in normal range with the 377B41 free- field microphone showing the corrected random response. C-26 824 Reference Manual...
  • Page 573 Graph 5 - The 824 in normal range with the 2551 free-field electret microphone showing the uncorrected random response. Graph 6 - The 824 in normal range with the 2551 free-field electret microphone showing the corrected random response. 9/29/09 C -27...
  • Page 574 Graph 7- The 824 in normal range with the 2551 free-field electret microphone showing random response with the random corrector. Microphone Response Tests with 824 The 824 was oriented with the LCD The following graphs show the effects on the performance facing up for these tests.
  • Page 575 Graph 1 - The 824 in normal range with the 2540 microphone Graph 2 - The 824 in normal range with the 2540 microphone and windscreen 9/29/09 C -29...
  • Page 576 Graph 3 - The 824 in high range with the 2540 microphone Graph 4 - The 824 in high range with the 2540 microphone and windscreen C-30 824 Reference Manual 9/29/09...
  • Page 577 Graph 5 - The 824 in normal range with the 377B41 microphone Graph 6 - The 824 in normal range with the 377B41 microphone and windscreen 9/29/09 C -31...
  • Page 578 Graph 7 - The 824 in high range with the 377B41 microphone and windscreen Graph 8 - The 824 in normal range with the 2551 free-field microphone. C-32 824 Reference Manual 9/29/09...
  • Page 579 Graph 9 - The 824 in normal range with the 2551 free-field microphone and windscreen. Directional Characteristics of the 824 with the 2540, 377B41 and 2551 free field microphones Test Setup • The 824 was tested in two different configurations as fol-...
  • Page 580 Graph 1 - 824 in the XY plane fitted with the 2540 microphone @ 1 kHz Graph 2 - 824 in the XY plane fitted with the 2540 microphone @ 2kHz C-34 824 Reference Manual 9/29/09...
  • Page 581 Graph 3 - 824 in the XY plane fitted with the 2540 microphone @ 4 kHz Graph 4 - 824 in the XY plane fitted with the 2540 microphone @ 8 kHz 9/29/09 C -35...
  • Page 582 Graph 5 - 824 in the XY plane fitted with the 2540 microphone @ 12.5 kHz Graph 6 - 824 in the YZ plane fitted with the 2540 microphone @ 1 kHz C-36 824 Reference Manual 9/29/09...
  • Page 583 Graph 7 - 824 in the YZ plane fitted with the 2540 microphone @ 2 kHz Graph 8 - 824 in the YZ plane fitted with the 2540 microphone @ 4 kHz 9/29/09 C -37...
  • Page 584 Graph 9 - 824 in the YZ plane fitted with the 2540 microphone @ 8 kHz Graph 10 - 824 in the YZ plane fitted with the 2540 microphone @ 12.5 kHz C-38 824 Reference Manual 9/29/09...
  • Page 585 Graph 11 - 824 in the XY plane fitted with the 377B41377B41 microphone @ 1 kHz Graph 12 - 824 in the XY plane fitted with the 377B41 microphone @ 2 kHz 9/29/09 C -39...
  • Page 586 Graph 13 - 824 in the XY plane fitted with the 377B41 microphone @ 4 kHz Graph 14 - 824 in the XY plane fitted with the 377B41 microphone @ 8 kHz C-40 824 Reference Manual 9/29/09...
  • Page 587 Graph 15 - 824 in the XY plane fitted with the 377B41 microphone @ 12.5 kHz Graph 16 - 824 in the YZ plane fitted with the 377B41 microphone @ 1 kHz 9/29/09 C -41...
  • Page 588 Graph 17 - 824 in the YZ plane fitted with the 377B41 microphone @ 2 kHz Graph 18 - 824 in the YZ plane fitted with the 377B41 microphone @ 4 kHz C-42 824 Reference Manual 9/29/09...
  • Page 589 Graph 19 - 824 in the YZ plane fitted with the 2551 microphone @ 8 kHz Graph 20 - 824 in the YZ plane fitted with the 377B41 microphone @ 12.5 kHz 9/29/09 C -43...
  • Page 590 Graph 21 - 824 in the XY plane fitted with the 2551 microphone @ 1 kHz Graph 22 - 824 in the XY plane fitted with the 2551 microphone @ 2 kHz C-44 824 Reference Manual 9/29/09...
  • Page 591 Graph 23 - 824 in the XY plane fitted with the 2551 microphone @ 4 kHz Graph 24 - 824 in the XY plane fitted with the 2551 microphone @ 8 kHz 9/29/09 C -45...
  • Page 592 Graph 25 - 824 in the XY plane fitted with the 2551 microphone @ 12.5 kHz Graph 26 - 824 in the YZ plane fitted with the 2551 microphone @ 1 kHz C-46 824 Reference Manual 9/29/09...
  • Page 593 Graph 27 - 824 in the YZ plane fitted with the 2551 microphone @ 2 kHz Graph 28 - 824 in the YZ plane fitted with the 2551 microphone @ 4 kHz 9/29/09 C -47...
  • Page 594 Graph 29 - 824 in the YZ plane fitted with the 2551 microphone @ 8 kHz Graph 30 - 824 in the YZ plane fitted with the 2551 microphone @ 12.5 kHz C-48 824 Reference Manual 9/29/09...

  • Page 595: Power/Current Draw Of 824 Using External Power

    Power/Current Draw of 824 Using External Power Stopped Running with Running with Running with Running with backlight OFF backlight ON backlight OFF backlight ON Power 0.012 0.96 W 1.28 W 1.73 W 1.72 W 2.21 W Not Charging Power 2.25 W 2.53 W...
  • Page 596 C-50 824 Reference Manual 9/29/09...

  • Page 597: Appendix D Glossary

    A P P E N D I X Glossary This appendix contains technical definitions of key acoustical and vibration terms commonly used with Larson Davis instruments. The reader is referred to American National Standards Institute document S1.1-1994 for additional definitions. Specific use of the terms defined are in the main body of the text.

  • Page 598: Community Noise Equivalent Level (Cnel, Lden

    L. The levels for the hourly periods from midnight to 7 a.m. have 10 added to them to represent less tolerance for noise during sleeping hours. The same occurs from 10 p.m. to 824 Reference Manual 9/29/09...

  • Page 599: Criterion Duration (Tc

    midnight. The levels for the hourly periods between 7 p.m. and 10 p.m. have 5 added to them to represent a lessened tolerance for noise during evening activities. They are energy summed and converted to an average noise exposure rating. Criterion Duration (T It is the time required for a constant sound level equal to the Criterion Level to produce a Noise Dose of 100%.

  • Page 600: Decibel (Db)

    Whenever the word level is used, this logarithmic form is implied. The decibel provides us with the possibility of representing a large span of signal levels in a simple manner as opposed to using the basic unit Pascal for e.g. acoustic measurements. 824 Reference Manual 9/29/09...
  • Page 601 It is not possible to directly add or subtract physical quantities when expressed in decibel form since the addition of logarithmic values correspond to multiplication of the original quantity. The word level is normally attached to a physical quantity when expressed in decibels; for example, Lp represents the sound pressure level.
  • Page 602 . In table 2 an illustration is made of values calculated on sound pressure, non-squared units. The original definition of decibel was intended for power- like quantities, such as sound power. If we consider sound pressure levels instead (usually denoted P in acoustics), the 824 Reference Manual 9/29/09...
  • Page 603 equation will be the same, since the “two” in the squared units will move from within the bracket and become a 20 log instead of a 10 log and thus compensate for using linear or quadratic units. Please note that it is not allowed to use 20 log for squared units, since that expression assumes that we use linear units, like sound pressure in acoustics or voltage in electrical engineering.

  • Page 604: Department Of Defense Level (Ldod

    It is defined in ANSI S1.25 as “the change in sound level Rate Factor (q), Exposure corresponding to a doubling or halving of the duration of a Factor (k) sound level while a constant percentage of criterion exposure is maintained.” The rate and the factors are given 824 Reference Manual 9/29/09...

  • Page 605: Far Field

    in the table below. Standard : ANSI S12.19 Exchange Rate, Q Exchange Rate Exposure Factor, k Factor, q 3.01 13.333 16.667 6.02 Far Field There are two types of far fields: the acousti c far field and the geometric far field. Acoustic Far Field : The distance from a source of sound is greater than an acoustic wavelength.

  • Page 606: Frequency Band Pass Filter

    Note table in Frequency Filter - Frequency Weighting. Frequency Filter - Weighted A special frequency filter that adjusts the amplitude of all parts of the frequency spectrum of the sound or vibration D-10 824 Reference Manual 9/29/09...
  • Page 607 unlike band pass filters. It can be composed of one or more of the following types: A-Weighting : A filter that adjusts the levels of a frequency spectrum in the same way the human ear does when exposed to low levels of sound. This weighting is most often used for evaluation of environmental sounds.

  • Page 608: Leq

    Microphone - Types : A device for detecting the presence of sound. Most often it converts the changing pressure associated with sound into an electrical voltage that duplicates the changes. It can be composed of one of the following types: D-12 824 Reference Manual 9/29/09...
  • Page 609 Capacitor (Condenser): A microphone that uses the motion of a thin diaphragm caused by the sound to change the capacitance of an electrical circuit and thereby to create a signal. For high sensitivity, this device has a voltage applied across the diaphragm from an internal source. Electret: A microphone that uses the motion of a thin diaphragm caused by the sound to change the capacitance of an electrical circuit and thereby to create a signal.
  • Page 610 Rules : 1. When making hand-held measurements, keep your body at right angles to the direction of the sound you are interested in and hold the meter as far from your body as D-14 824 Reference Manual 9/29/09...

  • Page 611: Near Field

    possible. Use a tripod whenever possible. 2. Measure the influence of other sources by measuring the background sound level without the source of interest. You may have to correct for the background. Near Field There are two types of near fields: the acoustic near field and the geometric near field .

  • Page 612: Noise Dose (D

    T is Measurement Duration is Criteria Time is TWA is Criteria Level q is exchange rate factor; see page D-8 "Exchange Rate (Q), Exchange Rate Factor (q), Exposure Factor (k)" Standard : ANSI S12.19 D-16 824 Reference Manual 9/29/09...

  • Page 613: Noise Exposure

    Noise Exposure (See Sound Exposure) OSHA Level (L The Average Sound Level calculated in accordance with the OSHA Occupational Safety and Health Administration Exchange Rate and Threshold Level. Preamplifier A part of the sound level meter that matches a particular model of microphone to the meter.

  • Page 614: Sound Exposure (Se

    ) this is called the sound exposure and has the units Pascal squared- seconds or Pascal squared- hours. P0 is the reference pressure of 20 µPa and T is the reference time of 1 second. It is then put into logarithmic D-18 824 Reference Manual 9/29/09...

  • Page 615: Sound Pressure

    form. It is important to note that it is not an average since the reference time is not the same as the integration time. Sound Pressure The physical characteristic of sound that can be detected by microphones. Not all pressure signals detected by a microphone are sound (e.g., wind noise).

  • Page 616: Sound Pressure Level (Spl, Lp

    20 µPa. The square of the sound pressure is a power-like quantity that can be expressed in the original form of the level definition ⁄ --------- - 10log D-20 824 Reference Manual 9/29/09...

  • Page 617: Sound Power(W

    Sound Pressure Level can be converted to sound pressure as follows. If the sound pressure is 1 Pascal, then the sound pressure level is --------------------- - 20log 20log 50000 20 4.699 94.0 dB 6 – • 20 10 Calibrators often use a level of 94 dB so they generate a sound pressure of 1 Pascal.

  • Page 618: Sound Speed, (C

    Exchange Rate is 3 dB then the TWA is equal to the L where T and K is the Exchange Rate Factor. It is used for hearing damage risk assessment. Standard : ANSI S12.19 D-22 824 Reference Manual 9/29/09...

  • Page 619: Time Weighting

    ⎛ ⎞ t ( ) ⁄ ⎜ ⎟ ∫ -- - 10 Klog ⎜ ⎟ TWA TC ⎝ ⎠ Time Weighting The response speed of the detector in a sound level meter. There are several speeds used. Slow : The time constant is 1 second (1000 ms). This is the slowest and is commonly used in environmental noise measurements.
  • Page 620 ----- - ------- - --- - λ where λ is the wavelength, c is the sound speed, f is the frequency in Hz, and ω is the radian frequency. It has the dimensions of inverse length. D-24 824 Reference Manual 9/29/09...

  • Page 621: Appendix E Memory Usage

    A P P E N D I X Memory Usage The System 824 has a memory size of 2 MB. This is generally more than adequate for measurements performed on a day-by-day basis. However, for applications such as noise monitoring where...

  • Page 622: Interval Records (Intv History Enabled

    Bytes Basic Interval Record Intv Save Ln's=[Yes] Intv Ln Table +384 Enabled by “Store Complete Histogram” setting on “Interval” tab of 824 Utility Wind/Tach = [Yes] LOG Memory Use: Interval Records Table E-2: Daily Records (Daily History Enabled) Options — add bytes shown if enabled...

  • Page 623: Estimating Memory Usage

    Divide this value into the amount of available memory in the 824 (see Tools | Memory display, generally about two million) and this is the number of days that can be gathered.
  • Page 624 = number of registers stored n x 506 bytes/record 31,977 TOTAL bytes used / day Sum lines 25 to 31 2,047,485 824's Memory Size ≈2,000,000 see TOOLS | Memory Enter total memory shown 64 days TOTAL Run Time in days until out of memory...

  • Page 625: 824-Log Memory Usage Worksheet

    824-LOG Memory Usage Worksheet Exceedance Memory Estimation Bytes Used Bytes Needed Line Basic Exceedance Record Excd Time-Hist 21+n n=estimated number of samples (129 bytes max) Wind/Tach=[Yes] TOTAL Bytes / Excd Add lines 1 thru 2 Anticipated Excd / Day Enter Number TOTAL Excd Bytes / Day Multiply lines 4 &...
  • Page 626 = number of registers stored n x 506 bytes/record TOTAL bytes used / day Sum lines 30 to 36 824's Memory Size ≈ 2,000,000 see TOOLS | Memory Enter total memory shown TOTAL Run Time in days until out of memory...

  • Page 627: 824-Ssa Memory Usage

    824-SSA Memory Usage Interval Records (Intv History Enabled) SSA Memory Usage: Interval Records Table E-8: 9/29/09 E -7...

  • Page 628: Time History Records (Time History Enabled

    Impl (option) Live Impl Flat (option) Leq Spectrum (option) Live Spectrum (option) Wind / Tach (option) Temperature (internal to instrument) (option) External Power Voltage (option) Battery Voltage (option) SSA Memory Usage: Time History Records Table E-9: 824 Reference Manual 9/29/09...
  • Page 629 Other Histories and Memory Usage bytes 20 bytes per record Run Log History 17 bytes per record Calibration Log History SSA File (Store) with ‘Enable Ln’ = [ No] 2503 each file SSA File (Store) with ‘Enable Ln’ = [Yes] 7623 each file SSA Memory Usage: Other Histories and Memory Usage Table E-10:...
  • Page 630 E-10 824 Reference Manual 9/29/09...

  • Page 631: Appendix F Slm Testing To Iec61672-1

    SLM Testing to IEC61672-1 This chapter presents information for testing the sound level meter function of the System 824 according to IEC61672-1 Section 9.3. These data represent the performance of the instrument when used with the Larson Davis Model 377B41 microphone.

  • Page 632: Average Frequency Response Corrections

    Average Frequency Response The following table presents the corrections for the average Corrections frequency response of the System 824 using a PRM902 preamplifier and a Model 377B41 free-field microphone, with and without a windscreen. This data include the effects of reflections and diffraction.
  • Page 633 -1.2 -1.0 -0.2 0.60 17782.79 -0.9 -0.8 -0.1 0.60 18836.49 -0.7 -0.7 0.60 19952.62 -0.5 -1.0 -0.5 0.75 Add numbers in this column to levels read on the 824 to correct the level at a specific frequency 9/29/09 F -3...

  • Page 634: Periodic Testing Of A-Weighted Sound Levels

    -0.1 0.25 1000.00 0.25 1995.26 -0.2 -0.1 -0.1 0.30 3981.07 0.35 7943.28 0.40 12589.25 0.50 15848.93 0.60 Add numbers in this column to levels read on the 824 to correct the level at a specific frequency 824 Reference Manual 9/29/09...

  • Page 635: A-Weighted Sound Levels At Upper And Lower Limits Of The Linear Operating Range

    The electrical design of the input device to insert electrical signals into the preamplifier is a series 18pF ± 5% capacitor. The Larson Davis ADP005 is used for this purpose. The ADP005 can be used for noise floor testing by attaching the included short on the front of the ADP005.

  • Page 636: Maximum Sound Pressure Level

    The battery power supply voltage range for which the System 824 conforms to this standard is 2.3 to 4.8 volts. The System 824 will shut down if the battery is below 2.3 volts when used with alkaline batteries and below 3.3 volts when used with NiMH batteries.

  • Page 637: Effect Of Electrostatic Discharges

    Effect of Electrostatic The System 824 is not affected by electrostatic discharges. Discharges Greatest Susceptibility to AC The mode of operation of the 824 that produced the greatest Power and Radio Frequency susceptibility to A.C power frequency and radio frequency Fields:...
  • Page 638 824 Reference Manual 9/29/09...

  • Page 639: Appendix G Miscellaneous Information

    Setup menu that are labeled permanent? Answer There are ten permanent IDs that come with the 824 that are the factory default settings for the various instruments in the 824. They are there as a starting point from which to make your own Setups and cannot be deleted.
  • Page 640 7. Press the down arrow key about eleven times until the underscore character is showing. 8. Press the check key. 9. Now recall all of the IDs that you want to be above the separator line. 824 Reference Manual 9/29/09...
  • Page 641 Question #2 What is the power or current drawn by the 824 through the external power jack? Answer Here is a sample of external power expectation showing both wattage and current: Stopped Running with Running with Running with Running with...
  • Page 642 The “Start Level” setting indicates where the histogram table from which Ln data is calculated begins. The table only has a range of 128 dB yet the 824 can measure over a 150 dB range when the Gain or Range settings are considered.
  • Page 643 160 dB so a “Start Level” of 35 dB will give a range of 35 dB up to 162.9 dB). Question #5 How are Leq values calculated in the 824 and how is that different than traditional non-DSP (Digital Signal Processor) instruments.
  • Page 644 The Leq is the true equivalent level for that two-second period as if the signal level were constant amplitude. Detailed Explanation: So what's the difference between sampled SPL and an Leq for the same period? It depends on whether you are using 824 Reference Manual 9/29/09...
  • Page 645 Thus for fast, the amplitude variability is greater so the sample rate must be faster. Inside the 824 we sample fast enough that the integration is always accurate and gives you the Leq data at the time period desired, i.e. all the energy received for that Leq period is contained within the Leq.
  • Page 646 Answer Yes. The Logic Input line on the control connector at the base of the 824 can be set to control the Run/Stop of the instrument. This input takes a zero to five volt digital signal and performs the function selected by the Logic-In setting found in the Controls menu (SETUP >...
  • Page 647 Tools > Memory > Create EEPROM Backup menu item. You may want to perform a User Reset if the settings stored in the memory of the 824 have become corrupted. A User Reset is performed whenever the firmware is upgraded.
  • Page 648 G-10 824 Reference Manual 9/29/09...
  • Page 649 Modifying Setups ........................10-9 Opening Setup Disk Files ....................10-12 Printing a Translated File ..................... 10-29 Retrieving setups from 824 ....................10-7 RT60 Select Options ......................10-34 Saving Setups to Disk Files ....................10-12 Selecting a Data set to view ....................10-27 Selecting Active Measurements ..................
  • Page 650 About 824 ............................3-20 824 display ..........................3-20 this manual ..........................1-1 AC Power ............................3-8 AC power adaptor ..........................1-19 AC Susceptibility ..........................F-7 Above 10 V/m ......................... F-6 AC/DC Output connector ..........................6-5 control settings ........................7-12 Filter ............................6-6 Accessories/Optional Equipment ....................1-16 Active ID ............................4-13 Advanced Time History marker text ..........................7-35...
  • Page 651 Audiometer Testing ........................13-1 Autostore ByTime Graph ........................11-29 ByTime Spectral History ..................... 11-29 ByTime Spectrum ........................ 11-29 Leq ............................11-26 Views ........................... 11-25 Back Erase ............................ 3-10 Back erase function ......................... 2-8 Backlight Time ..........................3-5 Backup EEPROM ..........................3-19 Battery Compartment .........................
  • Page 652 IDs ............................4-12 Instrument Definitions ......................3-29 secondary parameter .......................2-10 Settings Menu .........................4-18 Check Key .............................3-12 Check Menu ...........................7-59 Any Data ..........................7-65 Control Settings ........................7-65 example ..........................7-60 Exceedance History ........................7-77 Exposure ..........................7-73 Graph Menu ..........................7-64 Intervals ........................7-67, 7-76 Ln Centiles ........................7-70, 7-74 LOG Any Data ........................7-73 Mark Display ..........................7-62 Other Logging Check Menus ....................7-73...
  • Page 653 ISM ............................7-10 Logic input ..........................7-12 Logic Output .......................... 7-13 Logic Output #2 ........................7-16 Logic Output #2.time ......................7-16 Logic Output time ........................7-15 SSA, LOG ..........................7-11 Criterion ............................D-3 sound level ..........................D-3 time ............................7-19 Current Criterion ..........................
  • Page 654 Duration measurement ..........................D-12 E.A. Cal Tone ..........................7-16 EEPROM Backup ..........................3-19 Eight Hour TWA ..........................D-8 Electrical Input ..........................F-5 Electrostatic Discharges Effect on 824 ........................... F-7 Entering Settings ..........................A-33 Exceedance general ............................6-8 History Check Menu ......................7-77 iv-vi Index Model 831 Technical Reference Manual...
  • Page 655 History Display ........................5-52 History settings ........................7-40 Time History Display ......................5-55 Exceedance History Enable ............................ 7-40 Exceedance Time ........................7-41 Minimum Duration ........................ 7-40 Time History .......................... 7-41 Time History Period ......................7-41 Timed Excd Period ........................ 7-41 Triggering ..........................
  • Page 656 Repeat measurements ......................12-4 Settings Descriptions ......................12-3 Settings Menu .........................12-1 Snapshot Check Menu ......................12-12 Snapshot Data Storage ......................12-11 Snapshot, Automatic ......................12-6 THD Measurement .........................12-9 Time Domain Windows ......................12-4 Zoom ............................12-7 Filters 1/1, 1/3 Octave Filter Shapes ....................C-20 Fractional Octave Bandwidth ....................7-10 Fractional Octave Detector .......................7-9 Fractional Octave Display ......................5-11 Fractional Octave Fast Autostore ...................11-1...
  • Page 657 Enable ............................ 7-32 Exceedance History ......................A-57 History Data Variables ......................A-57 Interval History ........................A-59 Marker Text ........................... 7-35 Other Level ..........................7-33 Period ............................. 7-33 Period Units ........................... 7-33 Resolution ..........................7-34 ID Name ............................3-16 ID Setting Files Advanced Menu Layout ......................
  • Page 658 Input Electrical ..........................F-5 Instrument Definitions Delete ............................2-2 FFT ............................12-1 Logging (LOG) ........................2-4 Name ............................3-16 Rooms (RTA) .........................11-2 RT60-A/B (RTA) .........................11-17 SLM (ISM) ..........................2-4 SLM&RTA (SSA) ........................2-2 Types ............................2-2 Write Enable ..........................2-2 Write Protect ..........................2-2 Integrated Level Calculations ......................B-1 Interface Cables ..........................A-2 Interval Auto Stop ..........................7-38...
  • Page 659 View Key ..........................3-12 Keypad ............................3-1 DSP instrurments vs analog ....................G-5 glossary ........................... D-8 Leq vs sampled SPL ....................... G-5 Level ............................D-12 Dept of Defense ........................D-8 Linear Range A-Weight Limits ........................F-5 Links Manual (pdf) ..........................1-5 Spectral ..........................
  • Page 660 Mark Display ..........................7-62 Measuring Ranges ISM ............................6-9 LOG ............................6-9 SSA ............................6-4 Memory ............................3-27 display ............................3-27 low free memory icon ......................5-4 structure ..........................3-29 usage ............................E-1 Menu Scrolling ........................4-13, 4-15 Metrics Display ........................5-65, 5-69 Microphone guidelines ..........................D-12 what it measures ........................D-13 Microphones capacitor ..........................D-13 Conforming ..........................
  • Page 661 Inherent ............................ F-5 pink ............................D-16 projected noise dose ......................D-17 single event exposure level ....................D-17 white ............................. D-16 Note adding to downloaded file ....................10-21 Off time ............................13-23 On time ............................13-23 OSHA level ............................D-17 Other ............................. 7-73 Other Level Views .............................
  • Page 662 Display .............................3-4 display ............................3-4 External ..........................1-20 External Power current draw ....................C-49 External power current draw ....................G-3 Internal ...........................1-18 key ............................3-3 Monitor ...........................3-33 power conservation ........................3-8 Settings .............................3-6 settings ............................3-6 Powering Up ............................4-1 No Display ..........................3-4 Preamplifier definition ..........................D-17 input connector ........................1-13 Preparing for a Measurement ......................4-16 Preview Display ..........................3-11 Print Key ............................3-37...
  • Page 663 Read Commands .......................... A-10 Recall Data ............................2-13 Formatted Reports ........................8-8 ID Setting Files ........................7-1 stored data ..........................4-11 Reference Level Range ..........................F-1 Point, microphone ........................F-1 Sound Pressure Level ......................F-1 Remote Commands Setting Commands ........................ A-30 Remote Control "Any Data"...
  • Page 664 Querying Settings ........................A-31 Read Commands ........................A-10 RS-232 interface ........................A-1 RTA Settings Commands ......................A-51 Run Log Variables ........................A-65 Setting Commands ........................A-30 Setting List ..........................A-37 Tailored Report ........................A-45 Template Settings ........................A-36 Time History Variables ......................A-67 Types of History ........................A-55 Unsupported Misc. Commands .....................A-78 Warnings ..........................A-71 Report All, Long Report ........................8-14...
  • Page 665 Arm Settings Menu ........................ 11-9 Arm Time ..........................11-10 Auto RT60 ........................... 11-16 Autostore ..........................11-8 Autostore Settings Menu ....................... 11-8 Autostore Views ........................11-25 Average History Check Menu ...................11-38 Average Count ........................11-14 Avg History Check Menu ....................11-38 Bandwidth Setting .........................
  • Page 666 Rooms RC ..........................11-41 RT-60 display ........................11-33 RT60-A/B ..........................11-17 RTA Views ...........................11-19 Run Logic In .........................11-14 Run on Input .........................11-14 Save ByTime ..........................11-9 Settings Descriptions ......................11-6 Settings Menu .........................11-2 Spacial Average History ........................ 11-38 Spatial Ave Check Menu ......................11-37 Spatial Average Views ......................11-35 Title Setting ..........................11-6 Transducer ..........................11-7 Trig Logic In ........................11-12...
  • Page 667 power ............................3-6 Setup 824Utility ..........................10-10 Key ............................3-14 Menu ............................4-13 Report ............................ 7-43 SLM Check Menu Options ......................7-62 Smart Charger ..........................3-6 Sound average level (lavg) ......................... D-2 day-night average level ......................D-3 energy average(Leq) ......................D-21 exposure ..........................
  • Page 668 SLM Display ..........................9-9 Timer Mode ..........................9-16 Under Range ...........................9-14 Windscreen ..........................9-7 Sound Power Level ........................D-21 Sound Pressure Level (see Sound) ....................D-20 Sound Speed ..........................D-22 Spatial Average ...........................11-36 Specifications AC/DC Output ......................... C-5 AC/DC Output (ISM, LOG) ....................C-10 AC/DC Output (SSA) ......................C-13 AUD Mode ..........................
  • Page 669 Stopping Measurements ........................2-8 Storing Data ............................2-13 System Diagram ..........................1-15 System Settings ..........................10-9 Takt ............................... 3-21 Taktmaximal ........................... 2-4 TAL ..............................6-2 Template Settings ........................A-36 THD Measurement FFT Instrument ........................12-9 Tilde Symbol ID Setup ..........................4-14 Time allowed Exposure time(Ti) .....................
  • Page 670 Unpacking and Inspection ......................1-14 Unsupported Commands ......................A-78 Utility Software. See 824 Utility Vibration ............................D-23 View Key ............................3-12 Views .............................2-11 Any Data ..........................5-8 Any Impulse ..........................5-8 Any Level ..........................5-8 Any Time ..........................5-9 Choices ...........................2-12 Daily ............................5-58 Daily, wind conditions ......................5-61 Daily, windy percent ......................5-62 Exceedance History ........................5-52...
  • Page 671 Wavenumber glossary ..........................D-23 Weighting frequency ..........................D-10 time ............................D-23 Weighting Setting ........................... 7-6 Wind/Tach enable ............................. 7-29 Pause Enable .......................... 7-30 pulse source ........................... 7-30 pulse trigger voltage ......................7-30 settings ........................... 7-25 setup ............................7-26 views ............................5-69 Wind Direction Units ......................
  • Page 672 iv-xxiv Index Model 831 Technical Reference Manual...
  • Page 673 Total Customer Satisfaction Guaranteed 3425 Walden Avenue, Depew NY USA 14043 Phone: 716-926-8243 Toll Free: 888-258-3222 LarsonDavis.com FAX: 716-926-8215...

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