Lambda SR1 Operation Manual

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Operation Manual

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Characterisation,

Measurement &

Analysis

SR1 Audio Analyzer

Stanford Research Systems

Audio

Lambda Photometrics Limited

Lambda House Batford Mill

Harpenden Herts AL5 5BZ

United Kingdom

info@lambdaphoto.co.uk

W: www.lambdaphoto.co.uk

+44 (0)1582 764334

+44 (0)1582 712084

Revision 3.0.0 January, 2014

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Summary of Contents for Lambda SR1

Page 1 SR1 Audio Analyzer Operation Manual Stanford Research Systems Audio Distribution in the UK & Ireland Lambda Photometrics Limited Lambda House Batford Mill Revision 3.0.0 January, 2014 Harpenden Herts AL5 5BZ United Kingdom Characterisation, info@lambdaphoto.co.uk Measurement & W: www.lambdaphoto.co.uk +44 (0)1582 764334...
Page 2: Table Of Contents
2 Manual Revision History ........................... 8 3 Overview ........................... 9 4 User Interface ........................... 13 5 A Quick Example............................19 Part II SR1 Operation 1 File Menu ........................... 28 Save SR1 Configuration ................................29 Save Partial Configuration ................................30 Load Configuration ................................
Page 3 9 Setups Menu ........................... 278 Analog-Analog ................................279 Analog-Digital ................................281 Digital-Analog ................................283 Digital-Digital ................................285 Digital IO ................................287 10 Help Menu ........................... 288 Part III SR1 Reference 1 Front Panel Description ........................... 291 © 2014 Stanford Research Systems...
Page 4 SR1 Operation Manual 2 Rear Panel Descritpion ........................... 293 3 Specifications ........................... 296 4 Filter Reference ........................... 305 5 File Reference ........................... 306 6 Hardware Reference ........................... 310 Index © 2014 Stanford Research Systems...
Page 5 Getting Started Part Audio...
Page 6: Part I Getting Started
Connecting The Power Cord Your SR1 was shipped with a power cord appropriate to your location. SR1 operates from a 100V, 120V, 220V or 240V nominal AC power source with a line frequency of 50 or 60 Hz. Before connecting the power cord to the rear panel power entry module, please ensure the the LINE VOLTAGE SELECTOR card, located in the rear panel fuse holder, is set so that the correct AC input voltage value is visible.
Page 8: Manual Revision History
Preliminary Version shipped with first SR1s 10/09 2nd Preliminary version 12/09 Complete Through Tools Menu 1/10 Complete Manual 3/10 For SR1 v 1.1 3/10 Minor Printing Corrections 5/10 Updated for SR1 v1.1.6 7/10 Updated for SR1 v1.2 6/11 Updated for SR1 v1.4 1/14 Updated for SR1 v2.1.13...
Page 9: Overview
Walking Bits, and a J-test waveform designed to test the jitter susceptibility of devices. Analog Inputs SR1 offers both balanced and unbalanced analog inputs with full scale input ranges from 160 Vrms down to 62 mVrms. SR1's analog inputs are autoranging, meaning that for most input signals, the analyzer automatically sets the input range without any user interaction.
Page 10 Sweeps and Free Run SR1 operates in two different measurement modes: free-run and sweep. In free-run mode the analyzers make continuous measurements and continually updates the measurement results on the analyzer panels.The second mode, sweep mode, requires that several options be set.
Page 11 115.2 kBaud. TCP/IP GPIB commands may also be sent over a TCP/IP network via the rear-panel ethernet connector. SR1 follows the VXI-11 standard for the transmission of commands over TCP/IP. SR1 is fully COM enabled allowing applications such as Visual Basic to set and query instrument internals.
Page 13: User Interface
Like all Windows software, operating SR1 requires a pointing device and a means of entering text and numeric data. The instrument provides several options depending on the intended environment.
Page 14 Enter Finishes entering the new value. Function Keys Page Rotates through the seven pages of the page control on the SR1 screen. Moves the control with "focus" either to the next or previous control. (Tab Left/Right) Sweep Starts a Sweep. Equivalent to pressing the button on the speedbar.
Page 15 Local Upon receipt of a command from one of the remote interfaces SR1 is placed in "Remote" mode. Using this key returns the unit to local control. AutoReference. The contents of the currently focused control is examined. If it is a frequency, the frequency is moved to the frequency reference of the selected analyzer.
Page 16: Keyboard Shortcuts
SR1 Operation Manual Keyboard Shortcuts A number of keyboard shortcuts are available (using either an external keyboard or the virtual keyboard) to simplify the execution of common functions. Key Sequence Action <Ctrl> 1-7 Select the designated page (1-7) on the page control as the active page.
Page 17 Getting Started Unit Entries The Unit Entry is a type of control used extensively throughout SR1 that allows entry of numeric data in a range of different units. The example below shows the generator amplitude control for example. When the down-arrow is clicked, a the current value of the entry is shown in the drop-down list expressed in each of the allowed units.
Page 18 SR1 Operation Manual Normally the Unit Display auto-selects the appropriate unit-modifier for the currently displayed value. For instance 1.2x10 Vrms would be displayed as 1.2 Vrms. There are situations where it might be desirable to lock the unit-modifier selection. For instance we might want the display to readout as 0.0012 mVrms.
Page 19: Quick Example
Windows controls and their operation should be familiar. Start out by using the speedbar at the top of the SR1 screen to open the Analog Inputs panel and the Analog Generator panel, and from the Analyzers menu, set Analyzer 0 to Time Domain Detector. These three panels may automatically open when SR1 is powered up.
Page 20 Input Level indicators turn green, indicating the ranges are optimally adjusted. (The Input Level indicators are also visible at the bottom right of the SR1 screen.) Now we can add a little bit of distortion to the signal. Press the "New" button again on the Analog Generator panel and once again select a "Normal Sine".
Page 21 Note that the measured THD+N ratio is -60 dB. (1 mV / 1 V = 60 dB). To show how much more SR1 brings to a standard distortion measurement select the second analyzer (A1) as the FFT1 analyzer. When the panel is displayed, change the source of the Analyzer to "Other Analyzer".
Page 22 FFT lines (resolution). The resolution can be set to values between 256 lines and 32k lines. Unlike most Audio Analyzers, SR1's FFT analyzer doesn't operate at a fixed frequency range from DC to Fs/2. The Bandwidth control allows setting the measurement range to Fs/2, Fs/4, etc., all the way down to Fs/2048.
Page 23 Getting Started Now we're ready to zoom in on a portion of the the distortion product spectrum. Go back to Page 1 of the page control, and in the bandwidth control of the FFT analyzer select 500 Hz.In the "Center Frequency"...
Page 24 Sweep Source button to bring up the sweep source selection menu: SR1 has 3 main types of sweep sources: Time Sweeps, where the sweep occurs at fixed time intervals, Internal Sweeps, where the sweep occurs at fixed values of some internal parameter, and External Sweeps, where the sweep occurs at fixed values of some externally measured parameter.
Page 25 Getting Started Select the start amplitude as 100 uVrms and the stop amplitude as 100 mVrms. Leave the number of sweep steps at 30, but select "Log Step Size." Next we need to select that data that will be measured in the sweep.
Page 26 (100 uV/1V) = -80 dB. At the other of the sweep the the THD+N is 20*log( .1V / 1V) = -20 dB. This quick example only scratches the surface of SR1's capabilities, but should give you a feeling for how the instrument operates.
Page 27 SR1 Operation Part Audio...
Page 28: Part Ii Sr1 Operation
SR1 Operation Manual SR1 Operation File Menu The File Menu contains options for saving and recalling instrument configurations and also for printing. Save SR1 Saves the entire instrument setup to a configuration file. Configuration Save Partial Saves the entire instrument setup to a configuration file.
Page 29: Save Sr1 Configuration
The trace data option governs how SR1 will save data stored in graphs. "Never Save" means that no graph data will be saved along with the configuration file. The file, in this case, is a pure "settings" file.
Page 30: Save Partial Configuration
SR1 configuration file. After selecting this option, the Save Partial Configuration dialog box is diplayed. Select the portions of the instrument configuration to save and click "OK" to display the standard SR1 file save dialog box.
Page 31: Load Configuration
SR1 Operation 2.1.3 Load Configuration File Load Configuration loads the instrument's configuration based on the values found in the file selected with the standard Windows file open dialog box. After selecting the file, a dialog is displayed allowing selection of individual configuration areas. The default is to load all the configuration information in the file.
Page 32: Print Sr1 Screen
SR1 Operation Manual 2.1.4 Print SR1 Screen File Print SR1 Screen prints the full main window of the program, including menus and borders, to the current printer. Printer and paper options are selected from the File Print Setup dialog. Note that File Print SR1 Screen always prints the entire screen exactly as it appears.
Page 33: Print Setup
Print Setup File Print Setup displays the standard Windows print setup dialog box. When running the SR1 program from a Windows computer, use whatever printers have already been installed. When using the SR1 instrument, use the Tools menu to connect SR1 to a network and install and configure network printers.
Page 34: Edit Menu
SR1 Operation Manual Edit Menu The Edit menu supplies the standard Windows editing functions: Cut, Copy, Paste, and Delete. Deletes the currently selected text and copies it to the clipboard. Copy Copies the currently selected text to the clipboard without deleting it.
Page 35: Panels Menu
Panels Menu The Panels menu provides access to the various panels which control the operation of the instrument. SR1 panels are fixed size windows— they're not resizable. They can be minimized, maximized, or closed with the standard Windows tools: Multiple copies of the same panel may be maintained on different pages of the main display. In general, changes made to a panel on one page are automatically updated on the other pages.
Page 36: Analog Generator Panel
Generator. The two generators operate simultaneously and independently with different waveforms. Output Controls Fs controls the output sampling rate and D/A converter selection for the analog generator. SR1 uses two different types of D/A converters to generate high-quality analog waveforms, a 16-bit converter operating at a fixed output sampling rate of 512 kHz and a 24-bit converter which operates at a variety of sampling rates.
Page 37 SR1 Operation providing a maximum waveform frequency of 28.8 kHz Synchronizes the sampling rate of the analog generator to the digital audio output sampling rate set in the Digital I/O panel.This setting is useful for performing cross- domain measurements using the FFT Chirp waveform or Multitone techniques.
Page 38 SR1 Operation Manual Analog Generator Output Connections Output Impedance selects the Analog Generator output impedance. © 2014 Stanford Research Systems...
Page 39 SR1 Operation 25 , 75 , 600 Allowed impedance values for unbalanced outputs 50 , 150 , 600 Allowed impedance values for balanced outputs Waveform Controls The New button displays the Waveform Selection Submenu. The selected waveform will either be added to the output for one or both channels depending on the Mode setting.
Page 40 This type of burst is implemented in SR1 as a separate waveform. SR1 also offers the capability of bursting any waveform that can be configured in the generator, although with no guarantee that bursting will occur at zero-crossings.
Page 41: Analog Generator Units
An analog waveform with an amplitude of 1 Vp has an instantaneous peak value of 1 Volt. Vrms A sine wave with an amplitude of 1.414 Vp has an RMS amplitude of 1 Vrms. In SR1, © 2014 Stanford Research Systems...
Page 42 0 in dB units. Analog Generator Frequency Units The following table describes the units used by SR1 in setting the frequency of digital generator waveforms. All frequency units except Hz make use of the Frequency Reference which is set in the References Box on the Analog Generator Panel.
Page 43: Analog Generator Waveforms
2.3.1.2 Analog Generator Waveforms SR1's Analog Generator is capable of generating an enormous variety of different audio waveforms, from simple ultra- lo-distortion sines to complex synchronous multitone waveforms. Because of its unique architecture which allows different waveforms to be combined the generator offers almost limitless flexibility in providing the perfect audio test output.
Page 44 SR1 Operation Manual The Waveform Amplitude control sets the peak amplitude of most waveforms. The Waveform Frequency control sets the frequency of many waveforms. Generator Trigger Certain generator waveforms can generate a trigger, known as a "generator trigger" which can be used by the analyzers to synchronize the analyzer to a certain portion of the waveform.
Page 45 SR1 Operation Phased Sine* The phased sine waveform consists of two sines, one on channel A and one on Channel B with a specified phase difference between them. This waveform may not be combined with other waveforms. Synchronous Burst Sine* The synchronous burst sine is a sinewave capable of fast switching between two amplitude levels.
Page 46 Amplitude controls, as with all SR1 waveforms, the peak value of the noise output. The crest factor of the noise waveform, the ratio of the peak value to the rms value of the noise, is approximately 4.
Page 47 Nevertheless SR1 includes the MLS waveform because of its historical association with impulse response measurements. Amplitude controls, as with all SR1 waveforms, the peak value of the noise output. The crest factor of the MLS waveform, which is essentially a square wave, is close to 1.
Page 48 Frequency Spectrum of USASI Noise: 100 Hz 6dB/oct hipass + 320 Hz 6 dB/oct lopass Square Wave* SR1 square waves uses special hardware to generate clean analog square waves. As a result, square waves may not be combined with other waveforms in the analog generator. The square wave frequency is limited to a maximum of 50 kHz regardless of the selected analog generator sampling rate.
Page 49 SR1 Operation Ramp The ramp waveform consists of repetitive runs of integer numbers of "rising" and "falling" samples to produce triangle-like output waveforms. Because the runs are restricted to integer number of samples, the Ramp Frequency and Ramp Fractional Rise Time have limited resolution which is a function of the selected generator sample rate.
Page 50 If multiple columns are detected in the file, SR1 displays a dialog asking which column to load. The number of points read from the table is then displayed in the corresponding control.
Page 51 "Compliance" led will glow red and no waveform will be output. The compliance led may also show red if SR1 runs out of table memory to create a long chirp signal (say for a large number of FFT lines, or when large amounts of fft zoom are used. The chirp waveform may attempt to use interpolation in situations when not enough memory is available for the complete table, in which case the "Compliance"...
Page 52 SR1 Operation Manual multiplied by the inverse of the frequency response of the EQ file. When EQ is selected with chirp, the "Variable Sweep Rate" feature is enabled. Selecting Variable Sweep Rate changes the chirp sweep rate to equalize the time domain amplitude in a chirp with variable frequency domain amplitude.
Page 53 SR1 Operation sweep over the frequency span of the selected analyzer. Because of the synchronous nature of the chirp signal, a uniform window should be selected in the analyzer when using the log-sine chirp waveform. Selection of the associated FFT Analyzer is done with the Chirp Source control.
Page 54 MultiTone configuration panel specifies the use of the analog generator. The MultiTone waveform outputs a generator trigger once each cycle. When performing multitone analysis with the local SR1 generator be sure to use generator trigger as the analyzer trigger source to ensure proper phase calibration.
Page 55 SR1 Operation IMD Type SMPTE/DIN Combines a High Frequency Sinewave with a low frequency sinewave. For a generator Fs of 512 kHz the low frequency can be set between 10 Hz and 1 kHz. The High Frequency can be anywhere down to 5x the low frequency. The Amplitude Ratio (low freq/high freq) can be set to either 1:1 or 4:1 with the Amplitude Ratio control.
Page 56 SR1 Operation Manual The polarity check waveform uses a phased combination of two sine waves to produce a deliberately asymmetric waveform that points "up". When this waveform is applied to a device under test it is easy to see if the device properly maintains or inverts polarity by checking the output waveform using the time record of the Analyzer.
Page 57: Digital Generator Panel
2.3.2 Digital Generator Panel The Digital Generator Panel controls the operation of SR1's digital audio generator. The generator can be populated with many different waveforms— sines, square waves, ramps, etc. Many of the waveforms can be combined by the generator. For instance, if the generator is populated with sinewave and noise, than the output will be the sum of the sinewave and noise signals.
Page 58 SR1 Operation Manual Dither controls the type of dither used by the Digital Generator. The digital generator generates the waveform internally with higher precision than the maximum 24-bit digital output word. Noise with the selected probability distribution is added to the internal representation, and the result is truncated to the width specified in the Digital I/O Output Resolution control.
Page 59 Note that there is one set of references for both generator channels. Burst Controls The SR1 Digital Generator implements a Timed Burst mode which switches the overall amplitude of the combined waveform output between two different values. Burst Mode turns the burst feature on and off.
Page 60: Digital Generator Units
The amplitude and frequency of generator waveforms can be specified using a variety of units all of which are useful in different audio test scenarios. Because of the large number of waveforms that SR1 can generate and because it's useful to define amplitude in a way that simplifies the coupling between the...
Page 61 Computed from dBFS using the relation bits = 1.76 + (dBFS/6.02). For instance, half scale (-6.02 dBFS) is 0.76 bits. Digital Generator Frequency Units The following table describes the units used by SR1 in setting the frequency of analog generator © 2014 Stanford Research Systems...
Page 62: Digital Generator Waveforms
2.3.2.2 Digital Generator Waveforms SR1's Digital Generator is capable of generating an enormous variety of different audio waveforms, from simple sines to complex synchronous multitone waveforms. Because of its unique architecture which allows different waveforms to be combined the generator offers almost limitless flexibility in providing the perfect audio test output.
Page 63 SR1 Operation a combined waveform this checkbox allows the selected waveform to be toggled on and off while still outputting the remainder of the waveforms. The EQ checkbox appears for only certain waveforms. If EQ is checked, and an EQ file is selected on the generator panel, the actual generated amplitude for the waveform will be the nominal amplitude multiplied by the frequency response of the EQ file at the current frequency.
Page 64 Amplitude controls, as with all SR1 waveforms, the peak value of the noise output. The crest factor of the noise waveform, i.e. the ratio of the peak value to the rms value of the noise, is approximately 4.
Page 65 Nevertheless SR1 includes the MLS waveform because of its historical association with impulse response measurements. Amplitude controls, as with all SR1 waveforms, the peak value of the noise output. The crest factor of the MLS waveform, which is essentially a square wave, is close to 1.
Page 66 SR1 Operation Manual amplitude control appears on the waveform tab. USASI noise may be used in conjunction with generator bursting to generate a burst USASI signal suitable for transmitter testing. Frequency Spectrum of USASI Noise: 100 Hz 6dB/oct hipass + 320 Hz 6 dB/oct lopass...
Page 67 If multiple columns are detected in file, SR1 displays a dialog asking which column to load. The number of table points read from the table is then displayed in the corresponding control.
Page 68 "Compliance" led will glow red and no waveform will be output. The compliance led may also show red if SR1 runs out of table memory to create a long chirp signal (say for a large number of FFT lines, or when large amounts of fft zoom are used. The chirp waveform may attempt to use interpolation in situations when not enough memory is available for the complete table, in which case the "Compliance"...
Page 69 SR1 Operation Type of Measurement Generator Fs Analyzer Fs Analog Source, Select Digital ISR as the analog Select Digital as the Analyzer source Digital Measurement generator Fs. which automatically chooses ISR as (ADC) the analyzer Fs. Digital Source, Analog Select the desired digital audio...
Page 70 SR1 Operation Manual Be sure to select the "Uniform" window when using the log-sine chirp. Window functions attenuate the beginning and the end of the time record which means that some frequencies will be attenuated more than others by the window.
Page 71 SR1 Operation measurements. All of the details of the multitone waveform— tone frequency and amplitude, phase, etc. are configured using the MultiTone Configuration Panel. As a result, only the amplitude is specified on the waveform tab. The Export button allows the current multitone waveform to be saved in arbitrary waveform format for off-line analysis.
Page 72 SR1 Operation Manual IMD tab for DIM selection In all cases the Total Amplitude control sets the combined amplitude of all signals. The IMD waveform is designed to be used with the IMD analyzer. The analyzer automatically determines the type of IMD signal is being generated and automatically configures itself for the correct analysis. See IMD Analyzer section for more details.
Page 73 SR1 Operation Special Digital Test Waveforms SR1's digital audio generator includes several waveforms that are specific to the digital audio domain, i.e. they have no analog counterparts. These waveforms generate specific bit patterns in the embedded digital audio output signal. As such, they cannot be combined with other signals. Dither is not added to the special digital test waveforms.
Page 74 SR1 Operation Manual samples specified in the "Dwell" control and the the pattern is shifted left by one bit. When the one/zero is shifted out of the leftmost bit of the digital audio word it rotates back into the rightmost bit of the word.
Page 75 SR1 Operation The JTest waveform, conceived of by the late Julian Dunn, is designed to excite jitter due intersymbol interference in digital audio signal paths with reduced bandwdiths, such as long cables. The Jtest waveform is primarily a square wave at OSR/4, but the dc level is slightly shifted every 192 samples. The...
Page 76: Analog Inputs Panel
2.3.3 Analog Inputs Panel The analog inputs panel controls and monitors the configuration of SR1's XLR and BNC analog inputs. The first tab on the panel, Analog Inputs, contains most of the configuration controls. Note that Channel A and Channel B analog inputs can be configured separately. The Range box contains a checkbox to enable autoranging of the corresponding input.
Page 77 Note that the input level indicators are also displayed at the bottom of SR1's main window so that they are visible even when the Analog Inputs Panel is not displayed.
Page 78 SR1 Operation Manual Optional Input Filters The final tab on the Analog Inputs Panel contains the selection controls for the Optional Filters on the analog input boards. See the SR1 Hardware Reference for details on the optional filters. © 2014 Stanford Research Systems...
Page 79: Digital I/O Panel
SR1's digital audio inputs and outputs work with both the AES/EBU and S/PDIF standards for digital audio over a wide range of sampling rates from 24 kHz to 216 kHZ. SR1 also makes a variety of digital audio carrier measurements including carrier amplitude, sampling freqency, and output-input delay.
Page 80 Checking the Square Wave box tells SR1 that the input signal is not an AES/EBU or consumer digital audio signal but simply a square wave signal. When square wave is checked none of the analysis capabilities related to the embedded digital audio data stream or the channel status bits are active.
Page 81 The purpose of equalization is to reverse the lo-pass degradation of the digital audio carrier which results from transmission over long cable runs: Original Digital Audio Carrier After Long Cable Run (Using SR1's CableSim ) Long Cable Run + Input EQ Digital Input Sample Rate Controls Select the Digital Audio Input Sampling Rate ISR used by all digital domain analyzers.
Page 82 Digital Audio Input Sampling Rate (ISR) is set to the Digital Audio Output Sampling Rate (OSR) Measured ISR is set to the value measured by SR1. Status Bits The sample rate embedded in the digital audio channel status is used as the ISR. User The ISR is set to a fixed user-entered value.
Page 83 SR1 Operation Carrier Level displays the measured peak-to-peak amplitude of the digital audio carrier. The displayed value is only meaningful when the input connector is set to BNC or XLR— for optical or GenMon inputs the display shows the amplitude of an internal signal.
Page 84 SR1 Operation Manual Reserved In Highlights status fields marked "reserved" in the standard but which contain non-zero values. Data/Active Bits Display The Data/Active Bits indicator displays 2 rows of indicators, corresponding to the 24 data bits of each digital audio channel. The color of each indicator indicates the status of that bit over 1 digital audio block (1 block contains 192 frames) .
Page 85 Note that it is easily possible to generate more jitter than can be tolerated at SR1's digital audio inputs. The digital audio inputs will not lock if too much jitter is applied.
Page 86 SR1 Operation Manual and right) each with 32 bits and that each bit represents 2 UIs in biphase encoding (2*32*2 = 128). Jitter EQ. Sine and square jitter can be set to have a variable amplitude as a function of frequency by specifying a Jitter EQ file.
Page 87: Channel Status Panel
The channel status panel displays received channel status information and controls the transmitted channel status information. Channel status information is organized according to either the AES/EBU professional standard or the SPDIF consumer standard. SR1 relies on AES3-2003 and AES-2id-2006 for the professional standard and IEC60958-3 as the source for the consumer standard.
Page 88 These 4 byte counter values can be specified and additionally, if the "increment" checkbox to the right of each entry is checked, SR1 will increment the transmitted value by 1 each digital audio block.
Page 89 4 indicators which glow red if the corresponding flag is set and green if it is not. The professional standard defines byte 23 as a cyclic redundancy check (CRC) character. SR1 allows several options for the transmission of the CRC byte.
Page 90: User Status Panel
SR1 Operation Manual 2.3.6 User Status Panel The user status bits panel displays the transmitted and displayed user status bits for both channels grouped as 23 bytes. Since no universal standard for the formatting or meaning of the user status bits transmitted with digital audio data, the status bits are presented as raw hexadecimal numbers.
Page 91: Sweep Panel
The sweep source defines the "X-axis" of the sweep — it specifies a series of points at which SR1 will take measurements. There are four types of sweep sources: time sweeps, in which measurements are made at specified time intervals, internal sweeps,...
Page 92 SR1 Operation Manual The Sweep Panel Configuring the Sweep Source Pressing the Source... button opens the Sweep Source Selection Window. The different sweep sources are organized in a tree structure. Click on the appropriate source: Time, Internal, External, or Switcher Channels to display the options relevant for that particular source.
Page 93 "Intersample Delay" or "Absolute Time." If the source is "Intersample Delay," SR1 always waits at least a step size after getting settled sweep data before beginning a new measurement. If "Absolute Time" is chosen, the analyzer will begin a new measurement immediately after finishing the previous measurement if necessary.
Page 94 When SR1 measures the external sweep source, it requires that the reading be Settled. Refer to the...
Page 95 "Minimum Level" measurement. Click the Minimum Level "Meas..." button to open a window allowing the selection of any SR1 measurement to act as a qualifier for external sweeps. The analyzer will then need to obtain a settled value of the selected measurement that is greater than the specified minimum value before finding a new value of the actual sweep parameter.
Page 96 Configuring Switcher Sweeps SR1 is designed to work with the SR10, SR11, and SR12 Audio Switchers to allow users to switch both outputs from and inputs to SR1 during a sweep to enable testing of multiple devices. Configuration of a...
Page 97 SR1 Operation Configuring Sweep Data After a new sweep X-axis point is determined according to the selected Sweep Source, SR1 begins to search for settled values of each of the sweep data measurements. Up to 6 measurements may be selected for each sweep. To select the sweep data measurements, click on the numbered box in the sweep data section of the sweep panel.
Page 98: Settling Panel
2.3.8 Settling Panel While in sweep mode SR1 requires all measurements to "settle" before adding them to the sweep. Settling insures that the variability for the measurement, whether intrinsic to the measurement or due to transients arising from the sweep, is reduced to a predetermined level. Each measurement can have a different settling profile, each characterized by a precision, number of points, profile, threshold, and delay.
Page 99 SR1 Operation previous point must be within twice the tolerance of of the current point, the 3rd- previous point within 3 times the tolerance, etc. This is the most "lenient" of the settling profiles and reflects the fact that the variability of many measurements decreases as a function of time after a transient change.
Page 100: Monitors Panel
2.3.9 Monitors Panel The Monitor Panel controls a number of functions related to SR1's speaker/headphone output and the rear panel analyzer monitor outputs. Several different signals can be routed to the speaker/headphones. Some of these sources a monophonic, and are sent to both channels of the headphones and to the single speaker.
Page 101 SR1 Operation Monitor A0 The speaker and both headphone channels are fed the A0 monitor signal. See the discussion below on the monitor signals. Monitor A1 The speaker and both headphone channels are fed the A1 monitor signal. See the discussion below on the monitor signals.
Page 102: 2.3.10 Multitone Panel
FFT, instead of by making multiple laborious swept measurements. Setting up multitone testing on SR1 involves configuring the generator and the analyzer. Details of the analyzer configuration are discussed in the MultiTone Analyzer section.
Page 103 SR1 offers several phase distribution choices for multitone signals. "Zero" simply sets all tone phases to 0 which usually results in a signal with very high crest factor but which may be useful for comparison purposes.
Page 104 SR1 Operation Manual approximations to the full crest-factor minimization problem, which has no closed form solution. The various algorithms are described in the paper "Low-Crest-Factor Multitone Test Signals for Audio Testing" by Alexander Potchinkov (JAES v50 #9 p681). Once the tone placement options are selected, press "Create Default Tones"...
Page 105: 2.3.11 Clock Reference Panel
2.3.11 Clock Reference Panel All of SR1's clocks, for both analog and digital audio, can be slaved to an external clock signal specified on the Clock Reference panel. In the absence of an external clock source the sampling clocks are derived from an internal high-quality crystal oscillator.
Page 106 If lock is not checked, SR1 uses its own internal crystal oscillator as a clock source. The phase lock loop attenuates jitter of the reference signal by 6 dB/octave above 5 Hz.
Page 107: Analyzers Menu
SR1 Operation Analyzers Menu The core of SR1's measurement capabilities is found in its collection of analyzers. Each analyzer is represents a functionally related group of measurements and the controls related to those measurements. At any given time there are two active analyzers, denoted by A0 and A1. To change the type of the two active analyzers use the following selections from the Analyzers menu: Makes wideband amplitude, ratio, SNR, and THD+N measurements.
Page 108: Common Analyzer Features
Converter For analog signals, SR1 offers a choice of two analog-to-digital converters, each optimized for different measurements. The high-bandwidth (Hi BW) converter is a 16-bit converter operating at a fixed sampling rate of 512 kHz.
Page 109 SR1 Operation When making cross domain measurements that require the input analog sampling rate to be synchronized to the digital audio output When making IMD measurements. The Hi-Resolution converter has lower residual IMD distortion. Level Indicators For all analyzers except the Jitter analyzer the bottom portion of the analyzer panel displays the levels, frequencies, and relative phase associated with the selected inputs.
Page 110: Analyzer Units
1.414 Vp because that's the sinewave relationship between Vp and Vrms. Likewise, if the Time Domain Detector is configured for Peak response SR1 will display a result of 1 Vp, but if the units of the display are changed to Vrms the display will read 0.707 Vrms.
Page 111 SR1 Operation In other words an answer displayed by SR1 in Vp does not imply that a peak measurement is being performed, nor does an answer in units of Vrms imply that an rms measurement is being made. The units will always have their sinewave ratios but the method of measurement must be known separately.
Page 112 Jitter represents the deviation in time between the nominal and actual occurrence of zero-crossings in a signal. As such, time units are used to measure jitter amplitude. In SR1, jitter amplitudes can be expressed in seconds, or in "UI"s. The UI, or unit interval, is for a digital audio signal the smallest pulse width present in the digital audio signal.
Page 113 2 kHz gives a waveform frequency of 200 kHz. Engineering Units When a transducer is connected to the input of SR1 it is convenient to have measurement results displayed in the units of what the transducer is measuring rather than Volts. For instance, a microphone might be calibrated in V/Pa, or an accelerometer in V/g.
Page 114 SR1 Operation Manual Analyzer References The Analyzer References tab has fields which contain the reference quantities for the analyzer units. Note that all analyzers share one set of analyzer units– there are not separate sets of references for the FFT analyzer and the Time Domain detector, nor are there separate references for the A0 analyzer and the A1 analyzer.
Page 115: Time Domain Detector
SR1 Operation 2.4.2 Time Domain Detector The Time Domain Detector (TDD) performs the "classic" audio analyzer measurements— amplitude, ratio, crest factor, and THD+N, on both analog and digital audio signals. The Time Domain Detector operates much the same way that traditional analog audio analyzers worked: a notch filter is used to...
Page 116 Time Domain Detector: Analog Hi Bandwidth Inputs To fully exploit the capabilites of SR1's analyzers i is useful to understand exactly how SR1 functions for each of the three classes of inputs: analog signals using the Hi Bandwidth converter (HiBw), analog signals using the Hi Resolution converter (HiRes), and digital audio signals.
Page 117 SR1 Operation Because of the wide range of input amplitudes handled by SR1 (160 Vrms full scale to 62 mVrms full scale) the input signal may need to be either attenuated or amplified. For most signals, the autorange control can automatically select the appropriate attenuation or gain without user interaction. The level chain starts with a frequency measurement of both channels.
Page 118 SR1 Operation Manual automatically adjusts the input attenuation and gain, and an analog frequency measurement is made on both input channels. When the HiRes converter is selected, the two signals are digitized by a 24-bit stereo ADC. As in the HiBw case, the phase and level measurements are computed by the DSP. The Amplitude Chain, unlike the HiBw case, is implemented purely in the DSP.
Page 119 SR1 Operation Time Domain Detector Panel Rate The rate control sets the time interval over which the amplitude and levels are computed. Six fixed rates are available from 1/sec to 32/sec (the measurement interval is simply the inverse of the rate). The "Auto Fast"...
Page 120 SR1 Operation Manual measurement interval selected with the "Rate" control. Peak response calculates the peak value of the amplitude signal over the measurement interval. Quasi-peak filters the amplitude signal with a dual time- constant response to provide the dynamic characteristics specified in ITU-R BS 468.
Page 121 SR1 Operation -100 -120 -140 -160 -180 Notch Filter for Digital and Analog HiRes Inputs For HiRes analog and digital audio inputs, the bandpass filters with 1/3, 1/6, 1/12, and 1/24 Octave responses can be selected. © 2014 Stanford Research Systems...
Page 122 SR1 Operation Manual -100 -120 -0.3 -0.1 Normalized Freq. Softw are Bandpass Filters: 1/3, 1/6, 1/12, 1/24 Octave Digital and Analog HiRes Inputs for HiBw analog inputs, a single analog bandpass filter may be selected: © 2014 Stanford Research Systems...
Page 123 SR1 Operation Hardw are BP Filter for Analog HiBW Inputs Notch Filter Tuning The frequency of the tunable notch/bandpass filter can be set to a fixed frequency or tuned to one of several sources. To select a fixed notch/bandpass frequency, select the "fixed" radio button at the right of the Notch/BP panel.
Page 124 SR1 Operation Manual Bandwidth Limiting Filters Several different high and low-pass filters to limit the bandwidth of the amplitude measurement. These filters are only applied to the amplitude signal, they do not affect the level measurements. For low- frequency (high-pass) bandwidth limiting the following filters can be selected: BW Limit (High-Pass selection) <10 Hz...
Page 125 SR1 Operation satisfies the requirements of AES17-1998 (r2004) section 4.2.1.1. Passband ripple is < .1 dB, Stopband attenuation is > -60 dB for f>48 kHz. AES 80 kHz Selects a 4-pole elliptic low-pass filter with a passband edge of 80 kHz that satisfies the requirements of AES17-1998 (r2004) section 4.2.1.1.
Page 126 For analog HiBw inputs, the TDD offers variable postfilter gain. Typically the Gain selection can be left on "Auto" and SR1 will automatically optimize the postfilter gain. The level indicator above the gain selection indicates the current level of the postfilter signal, blue for less than half scale, green for greater than half scale, and red for overloaded.
Page 127: Fft (Single Channel)
Time Domain Detector. SR1's FFT analyzer can operate over the range from DC to Fs/2 with a resolution of 32k lines, or the spectrum can be "zoomed" by up to a factor of 1024 to apply the full 32k line resolution to a smaller portion of the frequency located anywhere within the full range.
Page 128 SR1 Operation Manual FFT1 Analyzer Block Diagram A block diagram of the FFT1 analyzer is shown above. The selected input signal is first optionally heterodyned to move the selected center frequency to the center of the FFT analysis range. The signal...
Page 129 SR1 Operation Unaveraged Pow er Spectrum of Sine+Noise Averaged (N=10) Pow er Spectrum of Sine+Noise The second spectral output computed by the FFT1 analyzer is the Linear Spectrum. The Linear Spectrum is computed by averaging the real and imaginary parts of each FFT separately. The average of the real and imaginary parts are then used to compute the Linear Spectrum amplitude and phase.
Page 130 SR1 Operation Manual Summary of FFT1 Analyzer Outputs Measurement Description Time Record The underlying time data used to compute spectra. When displayed on a graph this measurement produces an "oscilloscope" type display. Power Spectrum The amplitude of the power-averaged spectrum.
Page 131 Aliasing arises in sampled data systems because the real-world filters used to protect A/D converters have finite cutoff slopes. Each of the SR1's A/D converters is protected with either analog or a combination of analog and digital anti-aliasing filtering. For each converter there is some range of frequency below Fs/2 that is not fully protected to the level of the ultimate attenuation of the anti-aliasing filter.
Page 132 SR1 Operation Manual Resolution The resolution control determines the number of lines in the FFT spectra. Values from 256 lines to 32k lines can be selected. In the resolution control the time to acquire a time record for the selected resolution and current bandwidth selection is shown alongside the number of lines.
Page 133 It is well known that the application of a window functions is typically necessary to obtain maximum dynamic range for FFT measurements. The discrete Fourier Transform implemented by SR1 calculates a spectrum assuming the time record repeats continuously. Thus, if the signal being analyzed is not...
Page 134 Phase Controls The linear spectrum has phase as well as magnitude associated with it. Checking "Unwrap Phase" instructs SR1 to "unwrap" the phase by adding or subtracting 360º at appropriate break points to create a continuous phase curve. Phase Spectrum of 1 kHz LPF Without Unw rapping Sam e Spectrum w ith Phase Unw rapping On ©...
Page 135 SR1 Operation The Phase Threshold specifies a minimum amplitude at which to compute phase. This can be useful when the spectrum only has amplitude at discrete frequency points. If a phase threshold is not specified important phase information can be lost in the "phase noise" that is generated by the noise floor. In the example below the phase spectrum of a 3 kHz square wave is shown.
Page 136 The two spectral outputs of the FFT1 analyzer, the Power Spectrum and Linear Spectrum, can have weighting curves applied to them. Weighting curves are represented by files. The standard EQ files supplied with SR1 include: Weighting Filters None No weighting filter is applied.
Page 137 SR1 Operation cycle in the FFT time record. If the points are plotted by simply connecting adjacent samples a distorted picture of the actual time data may result. When "Time Display Interpolation" is turned on, band-limited interpolation is applied to the time record display to "oversample" the displayed points and produce a more accurate visual representation of the original time-signal.
Page 138 SR1 Operation Manual Chirp, Hi-Resolution ADC (Y Scale = 10 m Db/div) Chirp, Hi-Bandw idth ADC (Y-scale = 10 m dB/div) The unique property of the synchronous chirp, equal power in each FFT bin, makes it a powerful tool for quickly measuring the frequency response of audio devices.
Page 139 SR1 Operation Norm alized Frequency Response of Elliptical Filter If desired, the original chirp signal can be acquired first, without passing it through the DUT, and saved as an offline trace. Then after the spectrum through the DUT is acquired the graph's "Ratio" function can be used to normalize the output to the input producing a true frequency response plot such as the one seen above right.
Page 140 SR1 Operation Manual Residual Spectrum of 25 kHz, 1 Vrm s Sine from Com m ercial Function Generator As an example, the spectrum above shows the residual spectrum from a 25 kHz 1 Vrms sine wave generated by a commercial function generator. The THD+N in a 200 kHz bandwidth as measured by the TDD is -58.6 dB—...
Page 141: Fft (Dual Channel)
Typical Dual-Channel Response Measurem ent The diagram above shows a typical two-channel measurement setup. SR1's Generator provides the stimulus signal which can be a broadband source, such as noise or the FFT chirp signal, or can be narrowband.
Page 142 SR1 Operation Manual stage of decimation includes filtering to eliminate alias effects from the discarded portions of the frequency spectrum. The outputs are sent to two buffers which serves as the time records for the FFT2 analyzer. The time records for each channel are synchronized to the occurrence of a trigger. If the...
Page 143 The numerator, , is a complex quantity known as the cross-spectrum. When SR1 calculates the magnitude and phase of the frequency response it uses the following definitions: This technique provides a significantly more stable Frequency Response than if SR1 were to simply average the shot by shot frequency response .
Page 144 At the zeros of the filter, there is virtually no output from the filter and all the SR1 is measuring is uncorrelated noise, hence the zeros of the filter correspond to the regions of lowest coherence.
Page 145 SR1 Operation sine chirp stimulus has the fascinating property of being able to temporally separate the response due to the linear and non-linear portions of the DUT transfer functions. (See "Measurement of audio equipment with log-swept sine chirps" by Thomas Kite, AES Convention Paper 6269 presented at the 117th AES Convention, October 2004 for a succinct summary of the properties and advantages of using the log-sine chirp).
Page 146 The ETC is the magnitude of the analytic impulse. SR1 calculates the ETC from the anechoic frequency response. A frequency-domain window is applied to the anechoic frequency response to reduce alias effects. The result is transformed back to the time- domain to obtain the real part of the analytic impulse response.
Page 147 SR1 Operation Summary of FFT2 Outputs Measurement Description Level A, B Peak-based levels of both channels of the selected input domain. Time Record A,B The underlying time data used to compute spectra. When displayed on a graph this measurement produces an "oscilloscope" type display.
Page 148 SR1 Operation Manual The FFT2 Analyzer Panel Because both the A and B inputs of the selected input domain are always used by the FFT2 analyzer the Source selection for FFT only offers the choice of "Analog" or "Digital". The "Converter" and "Fs"...
Page 149 Aliasing arises in sampled data systems because the real-world filters used to protect A/D converters have finite cutoff slopes. Each of the SR1's A/D converters is protected with either analog or a combination of analog and digital anti-aliasing filtering. For each converter there is some range of frequency below Fs/2 that is not fully protected to the level of the ultimate attenuation of the anti-aliasing filter.
Page 150 It is well known that the application of a window function is typically necessary to obtain maximum dynamic range for FFT measurements. The discrete Fourier Transform calculated by SR1 calculates a spectrum assuming the time record repeats continuously. Thus, if the signal being analyzed is not...
Page 151 Phase Controls The linear spectrum has phase as well as magnitude associated with it. Checking "Unwrap Phase" instructs SR1 to "unwrap" the phase by adding or subtracting 360º at appropriate break points to create a continuous phase curve. Phase Spectrum of 1 kHz LPF Without Unw rapping...
Page 152 "Average" DC correction applied. Spectrum Weighting The spectral outputs of the FFT2 analyzer can have weighting curves applied to them. Weighting curves are represented by files. The standard EQ files supplied with SR1 include: © 2014 Stanford Research Systems...
Page 153 SR1 Operation Weighting Filters None No weighting filter is applied. A-Wt "A" weighing filter is applied. "A" weighting is specified in ANSI standard S1.4- 1983 and is typically used for noise and THD+N measurements with audio applications. C-Msg Wt The C-Msg weighting filter, specified in IEEE Std. 743-1995, is intended to be used for noise measurements associated with voice transmission telecommunications.
Page 154 The "Calc. Impulse Response" checkbox must be checked for SR1 to compute impulse response, anechoic frequency response, and the Energy-Time curve. The calculation of these measurements is time-consuming so the box should be left un-checked to obtain the maximum FFT update rate in situations where they are not needed.
Page 155 Using the FFT2 Analyzer With the FFT Chirp Source Like the FFT1 analyzer the FFT2 analyzer can be used with SR1's generator "FFT Chirp" waveform which produces a signal with uniform power in each FFT bin. The FFT2 analyzer makes one-shot frequency response measurements using the chirp source even easier—...
Page 157: Thd Analyzer
SR1 Operation 2.4.5 THD Analyzer The THD (Total Harmonic Distortion) analyzer uses FFT techniques to measure the total or relative amplitude in two groups of user specified group of harmonics. Unlike the Time Domain Detector, which uses time-domain techniques to integrate the total noise+harmonic power outside the fundamental the THD analyzer uses the FFT internally to selectively measure only the amplitudes of harmonics.
Page 158 The definitions of THD+N and THD both involve the ratio of distortion products to the amplitude of the fundamental. However most time-domain based analyzers, including SR1's TDD, cannot separately identify the amplitude of the fundamental and instead measure the ratio of the distortion products to the total power in the signal.
Page 159 SR1 Operation for instance, changing input ranges. Weighting When summing the harmonic amplitudes the analyzer can apply any of the standard weighing filters to the individual harmonic amplitudes. The table below lists the available weighting filter and their typical applications.
Page 160 SR1 Operation Manual The X-axis for this measurement is simply the harmonic number. Using the THD Analyzer with the Time Domain Detector The THD analyzer can be used together with the Time Domain Detector to make the most precise THD measurements possible.
Page 161: Imd Analyzer
All of these measurements have a long history and many pages have been written for and against each of them. SR1 can perform all these measurements by first generating the appropriate stimulus using the generator IMD waveform and then selecting the IMD analyzer to perform the measurement.
Page 162 SR1 Operation Manual The IMD Analyzer Panel Generator Selection The Generator control selects the generator that will be used for the test. Typically the analog generator will be selected with analog inputs and vice versa, however, cross domain measurements are possible on ADC and DAC devices by selecting a different generator.
Page 163 SR1 Operation SMPTE/DIN (f1 = low frequency, f2 = high frequency, U2 = amplitude of high freq. component) d2 = (U )/U2 f 2+f 1 f 2-f 1 d2+d3 d3 = (U )/U2 f 2+2*f 1 f 2-2*f 1 d2+d3+d4...
Page 164 SR1 Operation Manual Weighting When summing the harmonic amplitudes the analyzer can apply any of the standard weighing filters to the individual harmonic amplitudes. The table below lists the available weighting filter and their typical applications. Weighting Filters None No weighting filter is applied.
Page 165: Multitone Analyzer
In windowed mode a parameter can be entered which describes the maximum extent of the frequency shift and assists the analyzer in locating regions of tones, distortion, and noise. Multitone measurements with SR1 first require the configuration of the multitone generator using the Multitone Configuration Panel.
Page 166 SR1 Operation Manual Harmonic The vector containing only the bins that represent harmonics of tones present in Distortion Bins, ( A/ the generator signal. The vector containing intermodulation products of the tones up to the order specified on the analyzer panel. 2nd order IMD products, for instance, fall at...
Page 167 SR1 Operation Freq. Response: The vector of the ratios of the B channel rmagnitude response to the A channel Magnitude magnitude response. Ratio B/A Freq. Response: The vector of the differences between the B channel phase and the A channel Phase phase.
Page 168 The file selection box allows specification of an EQ file which is then applied as a weighting function to all MTA measurements. EQ files are files which specify a relative response as a function of frequency. EQ files are detailed in the SR1 File Reference.
Page 169 SR1 Operation Generator corresponding generator signal. Relative to The absolute voltage for each measurement is divided by the peak voltage of the Generator (Other generator signal for the other channel. Channel) Relative to Tone @ The absolute voltage for each channel is divided by the received amplitude of the Selected Frequency selected tone in the measurement channel.
Page 170 For broadcast or recorded multitone stimuli the generator trigger is obviously no longer useful as the SR1's generator no longer has any relation to the actual occurrence of the stimulus signal. Likewise, amplitude triggers may trigger on noise and miss the multitone signal. For these situations the analyzer provides a "validation"...
Page 171: Histogram Analyzer
This process continues for a predetermined number of input samples after which the histogram is displayed and the process repeats. SR1's Histogram Analyzer also has the capability of calculating a real-time gaussian fit to the histogram data and displaying it alongside the histogram.
Page 172 SR1 Operation Manual Histogram of 1 kHz Digital Sine The first histogram shows a 997 Hz digital audio sine wave with a sampling frequency of 48 kHz. Because the sampling frequency is not a multiple of the signal frequency each cycle of the digital audio sine uses slightly different values and the result is a histogram with a smooth continuum of amplitudes between ±1 FFS.
Page 173 SR1 Operation Sample Rate The Histogram Analyzer can examine each sample in the input data stream, or it can examine only every other, every 4th, etc. up to every 512th sample. Use the Sample Rate drop-down to control the fraction of points in the input record which are included in the histogram.
Page 174 SR1 Operation Manual Histogram Fit When "Do Fit" is checked the Histogram Analyzer fits a gaussian curve to the to each computed probability histogram. The parameters of the gaussian fit, the mean and standard deviation, are displayed in the panel. The graph below shows the histogram of analog white noise along with the generated gaussian fit.
Page 175: Octave Analyzer
SR1 Operation 2.4.9 Octave Analyzer The Octave analyzer (sometimes called an RTA or Real-time analyzer) measures the power present in full octave, 1/3 octave, and 1/12 octave frequency bins from 20 Hz to 20 kHz. The bin centers and shapes follow ANSI Std. S1-11 (2004). In the analog domain, the octave analyzer always uses the Resolution converter.
Page 176 SR1 Operation Manual Octave Mode Selection The octave mode selection box determines the fractional ocatve bands used to measure power. The allowed choices are full-octave, 1/3 octave, and 1/12 octave. Octave Averaging There are two averaging selections available for the octave analyzer, exponential time averaging and peak-hold averaging.
Page 177: 2.4.10 Jitter Analyzer
The jitter analyzer uses analog Phase Locked Loop hardware to extract the jitter signal from any one of SR1's digital audio inputs. The demodulated jitter signal is digitized and passed to the DSP processor which analyzes the jitter signal either in the time domain or frequency domain depending on the user's selection.
Page 178 SR1 Operation Manual complex FFT points) and averaging that power into the power computed for previous FFTs. This type of averaging does not reduce the noise floor of the spectrum but it does reduce the variation of the noise floor making it easier to see spectral details on the order of the noise amplitude. The Jitter Analyzer also computes the Linear Spectrum.
Page 179 Rate a square wave input, the square wave frequency. Jitter Analyzer Input Selection Unlike other SR1 analyzers selection of the input signal for the Jitter Analyzer is done on the Input section of the Digital I/O panel.Select either the BNC or XLR connectors, optical connector, or the digital audio output monitor.
Page 180 SR1 Operation Manual The Jitter Analyzer Panel (Time Domain Analysis) The Time Domain jitter analyzer has a selectable peak or RMS response which is selected with the "Detector" control. In the RMS mode the analyzer calculates the RMS value of the jitter over an interval whose length is the reciprocal of the specified Measurement Rate.
Page 181 These lines span the frequency range from DC to the value set in the "Bandwidth" control. The ADC used by the jitter detector, like all of SR1's converters is preceded by an anti-aliasing filter with a finite attenuation slope. As a result, some lines at the upper edge of the frequency range may not be protected against aliases to the full attenuation of the filter.
Page 182 SR1 Operation Manual Exponential, or continuous averaging, continuously updates the averaged FFT displays weighting recent spectra more heavily than older spectra. The number of averages in this case is only an approximation of how many spectra are included in the average. Linear averaging averages the specified number of spectra, all equally weighted, and then stops.
Page 183: 2.4.11 Digitizer
The heart of SR1's digitizer is an 80 MHz 8-bit transient digitizer with an effective analog bandwidth of approximately 20 MHz. The digitizer can store up to 2 Msamples of data in each record. A flexible trigger generator allows synchronization of the digitizer record with a variety of points on the carrier signal as well as external events.
Page 184 To begin digitizer acquisition press the "Acquire" button on the digitizer panel or the icon on the SR1 speedbar. Pressing the button opens a file dialog allowing the current digitizer record to be saved to disk or to load a previously saved digitizer record. The format of digitizer files is detailed in the SR1 File Reference.
Page 185 SR1 Operation Xmit Block Triggers on the transmission of a block preamble (Z-preamble) by the digital audio output generator. Ref Out Triggers on the transmission of a channel A subframe preamble (X-preamble) at the Preamble A digital audio reference output.
Page 186 SR1 Operation Manual be one, two, or three unit intervals long. If the one-two-three pattern is completely unrecognizable the digitizer will abort processing at this point. If the one-two-three UI pattern is recognized, the digitizer does a more careful measurement of the zero-crossing positions and attempts to recreate the original clock signal by minimizing the jitter at one of three user-selectable points throughout the input record.
Page 187 SR1 Operation Voltage Offset Leads to Different Positive and Negative Pulse Widths The same effect can by caused by a transmitter with different time constants for rising and falling edges. On an eye diagram an offset can be detected by observing that the points at which the positive and negative going pulses cross is above the "0 Volts"...
Page 188 SR1 Operation Manual To account for these processes the digitizer includes an "asymmetry" parameter when reconstructing the original clock. Instead of a single Unit Interval length, the digitizer assumes 2 unit interval lengths, one for positive pulses and one for negative pulses. The difference in the lengths of positive going pulses ), and negative going pulses (U ), is calculated and displayed as an "asymmetry"...
Page 189 SR1 Operation adjustable between 256 and 8k lines. Spectrum of 200 m UI 10 kHz Sinusoidal Jitter signal Checking "Probability" computes the histograms of the input amplitude, jitter amplitude, input pulse width and input pulse rate. For a digital audio (or clock) signal, the input amplitude histogram is dominated by two peaks corresponding to the positive and negative voltages of the signal: Typical Digital Audio Carrier Signal..
Page 190 Eye Diagram of Carrier w ith 0.2UI Square Wave Jitter As an example consider the eye diagram above produced by the digitizer looking at SR1's digital audio output with 200 mUI of added square wave jitter. For square wave jitter the pulse edges will occur at one of two times corresponding to the high and low portion of the square wave jitter signal.
Page 191: Displays Menu
SR1 Operation Displays Menu SR1 offers three different types of displays which present visually the measurements made by the various analyzers. The Displays menu offers options for creating and managing the different types of displays used by the instrument. Graph Opens a new Graph on the current page.
Page 192: Graph
X-axis. Stripchart traces show a scalar measurement, such as THD+N, as a function of time with a scrolling "stripchart" type display. Sweep traces show the data from an SR1 sweep with a fixed X-axis that is defined by the sweep and data values that are defined by on of the...
Page 193 SR1 Operation The Graph Display Panel Trace Listing The panel at the lower right of the graph shows the trace listing. Each trace is represented by a line in the listing such as: A1:FFT:Power Spectrum A The color of the line in the trace listing corresponds to the color of the graphed data. The checkbox at the left allows each trace to be separately turned on and off in the graph.
Page 194 SR1 Operation Manual Add Measurem ent Form The first two nodes of the tree represent the measurements available from the two analyzers, A0 and A1. The second two nodes of the tree contain measurements related to generic properties of the corresponding input signal: level, frequency and phase.
Page 195 SR1 Operation Copy Stores the trace in memory without removing it from the current graph. The stored trace can be pasted back in the current graph or a different graph by right-clicking in the graph area and selecting "Paste Trace" from the submenu.
Page 196 However, there are times when it is useful to be able to view several traces all plotted with the same scaling on the same axes. Clicking "Lock Axes" causes SR1 to plot all traces that have X and Y axes compatible with the active trace on the same axes as the active trace.
Page 197 SR1 Operation automatically autoscales the X-data each time a new point is added to the trace so that the full range of data is always shown on the graph. If "Fixed" is selected the graph scale is not updated automatically so that any new points that are added with X-values exceeding the current range will not be seen.
Page 198 SR1 Operation Manual FFT Cursors Tab For FFT-type traces, the FFT cursors tab offers some additional cursor measurements. Checking "Calc. Power" displays the RMS integrated power in the spectrum between the two cursors as well as the RMS integrated power outside of the two cursors.
Page 199: Trace Calculator
SR1 Operation The limit X and Y values can be all moved together with the arrow buttons at the bottom of the panel. This can be useful for creating a limit equal to an existing trace plus some error margin. Individual X and Y values in the limit can be changed as well.
Page 200 SR1 Operation Manual submenu the corresponding panel appears. For instance, after selecting the "Linearity" function the Linearity panel will be displayed: This panel displays several important features common to all the trace calculator functions. The single input trace is displayed at the top of the panel. Because linearity takes only one input argument, no mechanism for selecting the input trace is provided—...
Page 201 SR1 Operation over the input data range. RMS or Linear averaging can be selected. A third option, variance, does not return the average but rather the variance: the RMS average deviation from the mean. 2-sigma Returns a trace containing a constant value which exceeds 95% (2 ) of the y values within the input data range.
Page 202: Bar Chart
SR1 Operation Manual 2.5.2 Bar Chart The Bar Chart is optimized for the display of a single measurement. The chart consists of two main areas: the top portion consists of a large numerical display of the selected measurement and the bottom portion contains a bar chart showing the current value of the measurement along with statistics of the measurement: mean, maximum, minimum, and standard deviation.
Page 203 SR1 Operation and double-click on a measurement to select it. The "Settings" button displays the bar chart settings panel which contains additional configuration options which will be discussed below. button rescales the bar chart display setting the minimum and maximum of the display to the minimum and maximum observed value of the measurement.
Page 204 SR1 Operation Manual Max" is selected, the minimum and maximum recorded values of the measurement will be displayed on the bar chart as pink lines. When "Avg/Sdev" is checked, the average value of the measurement (mean) will be displayed as a solid black line with the range of ±1 standard deviation shown as a dotted blue line.
Page 205: Digitizer Display
2.5.3 Digitizer Display The digitizer display is designed to display the measurements calculated by SR1's optional Digitizer. Unlike the Graph, which can display many different traces corresponding to user-selected measurements, the 4 tabs of the Digitizer Display always display the same digitizer measurements.
Page 206 SR1 Operation Manual Icon Description Load a previously saved Digitizer Display. Saves the Digitizer Display to a file. Exports the currently displayed tab of the Digitizer Display to one of several file formats. The output file can bye a text file, a bitmap (.BMP) file, a Windows Enhanced Metafile (.
Page 207 SR1 Operation Time Record Tab The Time Record tab of the Digitizer Display shows the two amplitude vs. time measurements of the digitizer: input amplitude vs. time, and jitter amplitude vs. time. The input amplitude vs. time trace shows the raw digitizer data i.e. essentially an oscilloscope display of the input signal. The jitter vs. time trace shows the jitter amplitude calculated by the digitizer as a function of time.
Page 208 If there are fewer jitter data points than FFT lines SR1 will zero-pad the jitter data when computing the jitter FFT spectrum. The jitter record length display on the digitizer panel will be shown in yellow to indicate that insufficient data is available for an accurate jitter FFT spectrum.
Page 209 SR1 Operation Eye Diagram Tab The eye diagram is a plot of probability vs. amplitude and time with probability coded as color. The Digitizer Display assembles overlays the signal transitions corresponding to the "Jitter Detection" selection on the digitizer panel and calculates the probability of the signal appearing at a given time with a given amplitude.
Page 210 SR1 Operation Manual The Inner Upper Limit and Inner Lower Limit determine the minimum width of the eye opening. The limit box can be forced to be symmetrical around the time axis by checking the "Mirror Up/Down" box on the Inner Lower Limit tab.
Page 211 SR1 Operation that the entire limit box can be quickly scaled up or down. Limit settings can be saved to disk and recalled with the "Load" and "Save" buttons on the Eye Limits panel. When Eye Limit Testing is enabled, the text on the Limits button is drawn in when the eye diagram plot fails any of the limit tests.
Page 212: Other Display Menu Options
This options selects a new active page on the page control. Select a page from the submenu and the active page will be changed. The same action can be accomplished by simply clicking on the desired page tab at the right of the SR1 screen. Move Form To Page...
Page 213: Tools Menu
SR1 Operation Tools Menu The Tools menu provides access to options for customizing the operation and appearance of SR1, integrating SR1 into a network environment, and accessing standard Windows computer functionality. The Tools menu options are: Preferences Panel Opens the SR1 User Preferences panel Events Panel Opens the SR1 Events panel.
Page 214: Preferences Panel
Use the file selection button to select any SR1 configuration file to load at startup. "Last AutoSaved" tells SR1 to use the last Auto-Saved configuration file at startup. SR1 periodically saves a configuration file at the interval specified by "Autosave Interval."...
Page 215 SR1 Operation Analog Generator Maximum Output This selection limits the maximum analog generator peak voltage to the specified value. This can be useful in avoiding accidental over-voltages when the generator is connected to sensitive equipment. Knob & Keypad The two checkboxes turn on and off the sounds produced when the knob is turned, or a key on the front- panel keypad is pressed.
Page 216 Trace Initialization Selecting "SR1 Default" means that each time a new trace is added to a graph, the X and Y-axis units will be set to the SR1 default for that type of trace. For example, an FFT power spectrum trace will always be added with the X-axis in Hz and the Y-axis in Vrms.
Page 217 SR1 Operation Binary Array In/Out By default all remote data interchange with SR1 is done in ASCII format. To maximize transfer rate for large arrays "Binary Array In/Out" can be selected which instructs SR1 to transfer all array data in binary.
Page 218 The rear-panel serial port connector may also be used to communicate with SR1. The COM port selection is only relevant when SR1 is being run in demo mode on a PC. On the instrument all choice will be grayed out except the the port that is actually connected to the rear-panel connector. The other serial port options such as Baud Rate, Data bits, etc.
Page 219 VXI-11 Options tab by pressing "Security." The panel includes controls for creating a list of IP addresses that will be allowed to connect to SR1 as well as a list of IP addresses that will be denied access to SR1. By default, SR1 checks the allowed list first but if "Check Denied List First" is checked, then SR1 will check the denied list first.
Page 220: Events Panel
2.6.2 Events Panel The events panel allows the user to link the occurrence of certain events within SR1 to a variety of user specified actions: file logging, audio alarms, running of scripts, or the firing of COM events. Configuration of the events panel is not necessary during ordinary use of SR1 but can be used to create highly customizable test configurations.
Page 221 Channel status is sent, in both consumer and professional formats in 23 byte Change blocks. SR1 allows up to 5 bytes to be "watched," i.e. any change in the received channel status in that byte triggers the corresponding event. The watched bytes are configured in the "Config"...
Page 222 Occurs when the front panel knob is turned. The corresponding COM Event includes an argument identifying the direction and amount the knob has turned. Warning Occurs whenever SR1 issues a warning. The text of the warning is included as an argument by the corresponding COM event. Critical Error Occurs when SR1 encounters a critical error.
Page 223 5 "generic" COM Events labeled Event1 through Event5. To set up a subroutine in a SR1's scripting environment which traps a COM Event navigate the tree in the right-hand panel in the scripting window to the "Events" node and double click the event to be trapped. A subroutine declaration is started in the script window which marks the routine that will be called when the COM event is fired.
Page 224 Using Events with scripts gives the user a window into the "internals" of SR1 and can offer almost unlimited flexibility if used correctly. However, care must be used when customizing events with scripts. Associating time-consuming scripts with frequently occurring events can adversely affect SR1's response time and even hang the instrument.
Page 225 Up to 5 measurements may be monitored by the events system The 5 events (New Meas0-4) are fired when SR1 computes a new value for the associated measurement. Use the ellipsis (...) button next to the event and navigate the tree to associate a measurement with one the 5 events.
Page 226: Switcher Configuration Panel
Systems to provide a flexible system for multiplexing SR1's inputs and outputs, both XLR and BNC. SR10 is an XLR input switcher capable of connecting any two of its twelve XLR inputs to SR1's analog inputs. SR11 is an XLR output switcher capable of routing SR1's two analog output channels to any or all of its 12 XLR output connectors.
Page 227 The next set of controls specifies how SR1 will control the switchers: via the serial port (RS-232) or over the ethernet network. If Serial communications is selected then a serial cable must be connected from SR1's rear-panel serial port to the switcher's serial connector.
Page 228 SR1 Operation Manual the ethernet network. Ethernet addresses and port assignments are configured using the switchers' web interface. The "Networks" tab of the Switcher Configuration Panel displays the attached switchers by function: BNC ouput, BNC input, XLR output and XLR input. SR10 switchers are used for XLR inputs and SR11 switchers for XLR outputs while SR12 switchers can be used for BNC inputs and ouputs.
Page 229 "Edit" displays the Switch Info panel: The Switch Info panel allows renaming of the switch and displays the communication parameters for the switch. Pressing "Test" tests communication with the switcher, the button turns green if SR1 successfully communicates with the switch and red if not.
Page 230: Hardware Status
2.6.4 Hardware Status The Hardware Status panel is a diagnostic panel that is not needed for normal operation of SR1. During normal operation of the instrument, all the status indicators for all of the boards should display green. Should a red indicator appear, indicating a problem with the hardware, contact Stanford Research Systems for technical support and report which items are red in the hardware status panel.
Page 231: Networking
The controls and dialog boxes described are not unique to SR1— they are from the Windows XP operating system which underlies the instrument. As such, these controls will not be described in complete detail. Only the features relevant to normal use of SR1 will be discussed. The following networking options are available: Network Setup Set the instrument's IP address.
Page 232: Network Places
SR1 Operation Manual to "Internet Protocol" and right click on Internet Protocol and then click the "Properties" button below the list. For networks supporting automatic assignment of IP addresses select "Obtain an IP address automatically." Otherwise enter the IP address, subnet mask, gateway, and DNS information manually.
Page 233: Map Network Drive
SR1 Operation 2.6.5.3 Map Network Drive Select "Map Network Drive" to assign a drive letter to a folder on the network. Enter a drive letter name and browse the network to the desired folder. If "Reconnect at logon" is checked the mapping will be made permanent.
Page 234: Share Sr1
2.6.5.5 Share SR1 Selecting "Share SR1" allows sharing of the "user" folder (and its subfolders) on the SR1 hard disk with other network users. The user folder contains subfolders in which configuration files, EQ files, eye diagram limit specifications and logfiles are stored.
Page 235 SR1 Operation Click "Share this folder" to enable sharing of the folder. Use the Permissions button to set up a list of network users who will be allowed to access SR1. © 2014 Stanford Research Systems...
Page 236: Computer Functions
2.6.6.1 Printers Panel SR1 can print to a USB printer directly connected to the front-panel USB port or to any printer on the network. Click "Add a printer" to configure a new printer. When installing a printer on SR1 the printer driver files must be either in an accessible network location or on a USB drive connected to the instrument.
Page 237: Eject Drive
SR1 Operation 2.6.6.2 Eject Drive Select "Eject Drive" to safely shut-down a USB drive connected to SR1 before removing it. Select the drive to be shut down and press "Eject" before removing the drive. 2.6.6.3 Power Options Selecting "Power Options" allows setting the idle-time interval before SR1's computer shuts off the monitor or hard disk.
Page 238: Date Time
The virtual keyboard provides the functionality of a PC keyboard using only the mouse. Use the virtual keyboard for text entry (e.g. filenames) in situations where SR1 is not connected to a PC keyboard. The virtual keyboard can be selected via the main menu under the "Tools" category or using the front-panel keypad by pressing <Alt-Alpha>.
Page 239 SR1 Operation connected directly to the internet, or not. If SR1 is connected to the internet simply select "Update SR1" from the Tools menu and the instrument will automatically contact the update server at Stanford Research Systems. Follow the onscreen directions. The update server will determine if the installed firmware version is the most recent and if necessary, download and install all required files to update the firmware.
Page 240 After determining whether a more recent firmware version exists, download the appropriate patch from the website and place the file on a USB drive connected to SR1. To execute the patch open a Windows explorer window and navigate to the USB drive with the patch file. Double click on the patch file to begin the update process.
Page 241: Automation Menu
The SR1 Basic interface can only be accessed via the ethernet port and is particularly suited to control by programs written in Visual Basic, Microsoft Office, and other COM enabled languages.
Page 242: Remote Interface Panel
<Local> or <Device Clear> are placed in <angle brackets> to differentiate them from literal text. The bottom window of the panel shows SR1's responses to the received commands. Responses that are queued for sending but have not yet been sent are shown in italics— once sent they are shown in normal type.
Page 243: Scripting Window
The main window area is used for actually writing the script. Note the line numbers at the left. The two windows to the right show the functions available in the SR1 Basic interface along with a description of function arguments. At the bottom, a status bar shows the currently selected scripting...
Page 244 (This button is also found on the main SR1 speedbar) SR1 Basic Interface Window The right-hand window shows the SR1 Basic interface organized in a tree. The top two branches of the tree are "SR1" and "Events". The "SR1" branch shows the instrument objects and their properties through which the script interacts with SR1.
Page 245 SR1 Operation complex functions which can return values and take multiple arguments. In general, double clicking on any item in the SR1 Basic interface window inserts that text at the cursor location in the main script window. Properties Properties are either integer, floating point or "unit-ed" quantities. Integer quantities are read and set as...
Page 246 Call SR1.Displays.Graph(graphId).AutoScaleX() Input and Output with Scripts SR1 scripts can interact with the user in a variety of ways. The built-in VBscript function MsgBox displays a message window containing a user specified string and an "OK" button. For instance, the line: MsgBox("MsgBox Argument")
Page 247 UserChoice The UserChoice function displays a window with a drop-down box displaying a list of choices: dim x x = SR1.Instrument.UserChoice("Some Choices...", "A,B,C", 5) if x = "A" then Call SR1.Instrument.UserMessage("User Picked A",10) elseif x = "B" then Call SR1.Instrument.UserMessage("User Picked B",10)
Page 248 "A,B". As with UserChoice the function returns "-cancelled-" if cancelled is pressed and "-timedout-" if the timeout limit is reached before the user takes any action. UserLaunchChoice Presents a series of buttons with corresponding explanations. x = SR1.Instrument.UserLaunchChoice("Some Choices...", "A,B,C","Performs A,Performs B, © 2014 Stanford Research Systems...
Page 249 The function also returns "-cancelled-" and "-timedout-" on the occurrence of the corresponding events. UserInput The UserInput function displays a simple dialog allowing the user to enter a value. A default value can be shown. For instance, x = SR1.Instrument.UserInput("Input a numeric value...","122",25) creates the dialog box: © 2014 Stanford Research Systems...
Page 250 This can be done using "Script Logging." The script log form can be opened from the "Automation" entry of the SR1 main menu. When opened the log is blank. Scripts can interact with the log using the following functions from the "Scripting" section of the SR1 Basic interface: SR1.Scripting.
Page 251 VBScipt "err.raise" function: call err.raise(errNo (int) , errorSource (string) , errorDescription (string)) The SR1 Basic Interface includes a built-in flag, SR1.Scripting.Terminate, which is set true when the user presses the stop ( ) button on the scripting panel. A subroutine can be included in user...
Page 252: Learning Mode
2.7.3 Learning Mode SR1 incorporates a "learning mode" to facilitate script development.When learning mode is enabled, if a script is not currently open, a new script will be created. The corresponding scripting commands for all subsequent keypresses, menu selections, panel entries, etc.will then be incorporated into the script window.
Page 253: Quick Measurement Menu
In the following sections each quick measurement will be described. For each measurement the cabling requirements from SR1 to the EUT will be given, followed by a description of the analyzer and generator configuration for that measurement. Finally, the displays created for each measurement, in both free-run and swept mode, are detailed.
Page 254: Setup Panel
SR1 Operation Manual 2.8.1 Setup Panel The Setup Panel records basic input and output information for all subsequent quick measurements. First, select the domain (analog or digital) for the measurement input and outputs. The input and output domains do not need to be the same, i.e. cross domain measurements may be made. Next, select the number of input and output channels and the connector (BNC, XLR, or for digital audio signals Optical) for the inputs and outputs.
Page 255: Snr Panel
Signal-to-Noise ratio. Cabling Configuration The output of SR1's analog or digital generator is connected to the EUT's input. The output of the EUT is connected to SR1's analog or digital inputs. The number of inputs and outputs and the connectors used...
Page 256 SR1 Operation Manual Refer to the Settling Panel chapter for a more detailed discussion of what each of the controls means.In general, specifying a smaller precision window and larger value for nPoints will decrease the noise and "glitches" in the sweep at the expense of increasing the time required for the sweep. Some experimentation may be required, depending on the characteristics of the EUT, to find the optimal values of the settling parameters.
Page 257: Reference Panel
Cabling Configuration The output of SR1's analog or digital generator is connected to the EUT's input. The output of the EUT is connected to SR1's analog or digital inputs. The number of inputs and outputs and the connectors used...
Page 259: Level Panel
EUT for a range of input amplitudes. Cabling Configuration The output of SR1's analog or digital generator is connected to the EUT's input. The output of the EUT is connected to SR1's analog or digital inputs. The number of inputs and outputs and the connectors used...
Page 260 SR1 Operation Manual Refer to the Settling Panel chapter for a more detailed discussion of what each of the controls means.In general, specifying a smaller precision window and larger value for nPoints will decrease the noise and "glitches" in the sweep at the expense of increasing the time required for the sweep. Some experimentation may be required, depending on the characteristics of the EUT, to find the optimal values of the settling parameters.
Page 261: Thd+N Panel
Cabling Configuration The output of SR1's analog or digital generator is connected to the EUT's input. The output of the EUT is connected to SR1's analog or digital inputs. The number of inputs and outputs and the connectors used...
Page 262 SR1 Operation Manual Refer to the Settling Panel chapter for a more detailed discussion of what each of the controls means.In general, specifying a smaller precision window and larger value for nPoints will decrease the noise and "glitches" in the sweep at the expense of increasing the time required for the sweep. Some experimentation may be required, depending on the characteristics of the EUT, to find the optimal values of the settling parameters.
Page 263: Frequency Response Panel
EUT. Cabling Configuration The output of SR1's analog or digital generator is connected to the EUT's input. The output of the EUT is connected to SR1's analog or digital inputs. The number of inputs and outputs and the connectors used...
Page 264 SR1 Operation Manual Because the frequency response quick measurement is a vector measurement it has different settling options compared to other quick measurements. The only settling profile available for vector measurements is "average." The nPoints control, in this case, dictates how many FFTs will be averaged before the result is displayed.
Page 265: Distortion Panel
EUT output with the fundamental notched out. Cabling Configuration The output of SR1's analog or digital generator is connected to the EUT's input. The output of the EUT is connected to SR1's analog or digital inputs. The number of inputs and outputs and the connectors used...
Page 266 SR1 Operation Manual channels) Free Run Configuration For THD analysis, a barchart display is created for each output channel showing the instantaneous THD of the EUT. For individual harmonic amplitude, a graph is created with a trace for each output channel showing the...
Page 267: Imd Panel
(IMD) measurements: SMPTE, CCIF, and DIM. Cabling Configuration The output of SR1's analog or digital generator is connected to the EUT's input. The output of the EUT is connected to SR1's analog or digital inputs. The number of inputs and outputs and the connectors used...
Page 268 SR1 Operation Manual Refer to the Settling Panel chapter for a more detailed discussion of what each of the controls means.In general, specifying a smaller precision window and larger value for nPoints will decrease the noise and "glitches" in the sweep at the expense of increasing the time required for the sweep. Some experimentation may be required, depending on the characteristics of the EUT, to find the optimal values of the settling parameters.
Page 269: Crosstalk Panel
Cabling Configuration The output of SR1's analog or digital generator is connected to the EUT's input. The output of the EUT is connected to SR1's analog or digital inputs. The number of inputs and outputs and the connectors used...
Page 270 SR1 Operation Manual Refer to the Settling Panel chapter for a more detailed discussion of what each of the controls means.In general, specifying a smaller precision window and larger value for nPoints will decrease the noise and "glitches" in the sweep at the expense of increasing the time required for the sweep. Some experimentation may be required, depending on the characteristics of the EUT, to find the optimal values of the settling parameters.
Page 271: 2.8.10 Interchannel Phase Panel
For analog measurements the A channel of the analog generator should be teed and connected to both the A and B inputs of the EUT. For digital measurements simply connect the SR1 generator to the EUT inputs. In both cases the EUT outputs should be connected to the appropriate (analog or digital ) inputs of SR1.
Page 273: 2.8.11 In/Out Phase
Cabling Configuration The output of SR1's analog or digital generator is connected to the EUT's input. The output of the EUT is connected to SR1's analog or digital inputs. The number of inputs and outputs and the connectors used...
Page 274 SR1 Operation Manual group delay traces) are added for each amplitude setting in the sweep. © 2014 Stanford Research Systems...
Page 275: 2.8.12 Automated Measurements And Reports
SR1 Operation 2.8.12 Automated Measurements and Reports Each time a quick measurement is performed, either in free-run or sweep mode, the results are accumulated in a formatted report. The report includes a header page which details the setup configuration entered in the quick measurement...
Page 276 SR1 Operation Manual To display the report after measurements have been made, select "Report" from the Quick Measurements menu. The report preview window includes options for page navigation, zooming and scaling, printing, and exporting the report to .PDF or .HTML format.
Page 277 SR1 Operation The Automated Measurement Panel allows selection of a group of quick measurements to be performed sequentially. The measurement results for each selected measurement are accumulated in a report. To clear the report in preparation for a new round of measurements press "Clear Report." To include a text note in the report enter the text in the "Notes' field and press "Update Report".
Page 278: Setups Menu
SR1 Operation Manual Setups Menu The Setups menu allows SR1 to quickly be configured for many common audio measurements. These pre-programmed setups can be used as a starting point to customize your own configuration files. See Saving SR1 Configurations for details. The setups are categorized by the domain of the stimulus signal...
Page 279: Analog-Analog
28 kHz FFT This setup configures SR1 for a basic audio band FFT. The Hi-resolution converter is selected for maximum dynamic range. The A0 analyzer is configured as a dual channel FFT analyzer with a span of 28.8 kHz and continuous averaging.. The Analog Generator is loaded with a low-distortion sine waveform set to a default frequency of 1 kHz and an amplitude of 1 Vrms.
Page 280 SR1 Operation Manual THD+N vs. Amplitude Sweep Performs a THD+N vs. amplitude stereo sweep. The A0 and A1 analyzers are set to Time Domain Detector in order to measure THD+N. A low distortion 1 kHz sine waveform is setup with an amplitude sweep range of 50 mVrms to 5 Vrms in 22 logarithmic steps.
Page 281: Analog-Digital
ADC or other digital output equipment. This setup configures SR1 for a basic audio-band FFT. The A0 analyzer is configured as a dual channel FFT analyzer with a span of 28.8 kHz and continuous averaging.. The Analog Generator is loaded with a low-distortion sine waveform set to a default frequency of 1 kHz and an amplitude of 1 Vrms.
Page 282 SR1 Operation Manual THD+N vs. Frequency Sweep Performs a THD+N vs. frequency sweep. The A0 and A1 analyzers are set to Time Domain Detector order to measure THD+N of both channels. A low distortion 1 Vrms sine waveform is setup with an frequency sweep range of 20 Hz to 20 kHz in 22 logarithmic steps.
Page 283: Digital-Analog
This setup configures SR1 for a basic audio band FFT. The Hi-resolution converter is selected for maximum dynamic range. The frequency range of the FFT is 1/2 the sampling rate of the digital output.
Page 284 SR1 Operation Manual be adjusted to suit the noise level of your signal. The FFT resolution is defaulted to 4k points, adjust this to obtain the proper balance of update rate vs. frequency resolution. THD+N vs. Amplitude Sweep Performs a THD+N vs. amplitude stereo sweep. The A0 and A1 analyzers are set to...
Page 285: Digital-Digital
This setup configures SR1 for a basic audio band FFT. The Hi-resolution converter is selected for maximum dynamic range. The A0 analyzer is configured as a dual channel FFT analyzer with a span of 28.8 kHz and continuous averaging..
Page 286 SR1 Operation Manual Detector in order to measure THD+N. A low distortion 1 FFS sine waveform is setup with an frequency sweep range of 20 Hz to 20 kHz in 22 logarithmic steps. Page 2 displays a graph of the A and B channel THD+N vs.
Page 287: Digital Io
Jitter Measures both RMS Jitter and the Jitter spectrum with SR1's jitter generator off. This setup is used to measure the intrinsic jitter output from a DUT. A0 is setup as a time domain jitter analyzer to measure rms jitter while A1 is setup to measure the jitter frequency spectrum.
Page 288: 2.10 Help Menu
SR1 Operation Manual 2.10 Help Menu SR1 Help Opens the help browser containing the SR1 help file. The contents of the helpfile and printed manual are the same. About SR1 Displays the "About SR1" panel listing the version of instrument software. If the software is running on the instrument (as opposed to demo mode) the serial number of the instrument is also displayed.
Page 290 SR1 Reference Part Audio...
Page 291: Part Iii Sr1 Reference
The two USB connectors may be used to connect a USB drive, a USB printer, or a USB mouse or keyboard. E) Main Screen Color LCD screen on which the SR1 software runs. SR1 is sold with two screens, the standard VGA (640x480) display and the optional XGA (1024x768) screen. F) Knob Use the knob to modify the value of the screen control which currently has focus.
Page 292 O) Analog Input Connectors Contains the analog intput connectors.SR1 accepts analog inputs on either the XLR or BNC connectors. Selection of the input connector as well as other input parameters (coupling, range, etc.) is made on the Analog Inputs panel.
Page 293: Rear Panel Descritpion
A) Power Entry Module Connect the supplied power cord to the power entry module to provide AC power to SR1. Make sure that the card on the power entry module shows the correct AC line voltage (100,120,200,240) for your locale.
Page 294 SR1's analog generator burst modes.) L) AES Reference In Use this input to lock the SR1's internal clock to an external digital audio reference signal (as defined by AES11-2003). Configuration of the clock reference is done on the Clock Reference panel.
Page 295 Clock Reference panel. R) Video Reference In Use this input to lock the SR1's internal clock to an external video (NTSC, PAL, or SECAM) signal. Configuration of the clock reference is done on the Clock Reference panel. S) Ext. Trigger In This TTL input triggers any analyzer configured to use "External Trigger."...
Page 296: Specifications
SR1 Operation Manual Specifications Analog Signal Generator General Characteristics Amplitude Range (rms) 10 μV to 28.3 V (balanced) 10 μV to 14.1 V (unbalanced) Amplitude Accuracy ±0.5 % (±0.043 dB) at 1 kHz Frequency Range High BW DAC 10 Hz to 200 kHz High Res.
Page 297 SR1 Reference 20 Hz to 57.6 kHz –102 dB+ 1.4 μV (57.6 kHz BW) Hi Res DAC, Fs = 64 k Hz 1 kHz, 4 Vrms -112 dB (22 kHz BW) 20 Hz to 20 kHz –106 dB+ 1 μV...
Page 298 SR1 Operation Manual Square 10 Hz to 50 kHz frequency range Ramp Fs / N frequency range (N = 20), adjustable rise/fall fraction Arbitrary 256 Samples to 136k Samples Polarity 10 Hz to Fs / 4 frequency range Constant (Offset)
Page 299 SR1 Reference SMPTE/DIN, CCIF/DFD, DIM/TIM Noise White, Pink, Filtered White/Pink, USASI Maximum Length Sequence from 2 to 2 samples repetition interval. Ramp /N frequency range (N = 20), adjustable rise/fall fraction Arbitrary 256 Samples to 136k Samples FFT Chirp Equal power in each FFT bin. Frequency response can be modified with an EQ file.
Page 300 SR1 Operation Manual Signal Measurements General Analog Input Characteristics Amplitude Range (rms) 62.5 mV to 160 V Input Configuration XLR, BNC, Generator Monitor, Digital Audio Common Mode Input Impedance Balanced 200 k? / 95 pF Unbalanced 100 k? / 185 pF...
Page 301 SR1 Reference Analog Signal Meters RMS Level Meter ±0.5 % (±0.043 dB) Accuracy (1 kHz ref) Flatness (rel. 1 kHz, Amp. = 4 Vrms) 20 Hz to 20 kHz <±0.008 dB (typ. < ±0.003 dB) 10 Hz to 64 kHz <±0.020 dB 10 Hz to 200 <±0.030 dB...
Page 302 SR1 Operation Manual 1 kHz, 4Vrms –111 dB (22 kHz BW) 20 Hz to 20 kHz –107 dB + 0.8 μV (22 kHz BW) –101 dB + 1.3 μV (57.6 kHz BW) High Res. ADC (Fs = 64 kHz) 1 kHz, 4Vrms –111 dB (22 kHz BW)
Page 303 SR1 Reference Number of Lines 256, 512, ... 32k Processing 40-bit floating point Windows Blackman Harris, Hanning, Hamming, Equiripple, Flattop, Gaussian, Kaiser, Uniform, Rife Vincent 4, 5 and 10 term Zoom Span can be narrowed by up to 512x Heterodyne Narrowed span can be centered anywhere in the measurement range.
Page 304 SR1 Operation Manual General Computer Interfaces GPIB, RS-232, Ethernet, COM. All instrument functions can be controlled. Reference Input Sources AES3 (24 Hz to 216 kHz),sine or TTL (8 kHz to 32 MHz), video (NTSC/PAL/ SECAM) Reference Output Format AES3 (24 Hz to 216 kHz)
Page 305: Filter Reference
SR1 Reference Filter Reference SR1's analog input boards have provision for the installation of up to 4 optional filters. Each filter can be inserted in the signal chain after the Notch/Bandpass filter and before the postfilter gain elements. (Note that the optional filters only affect Hi Bandwidth analog measurements).
Page 306: File Reference
SR1 Operation Manual File Reference EQ Files (.EQ) EQ files are XML files that represent a real or complex (magnitude or magnitude and phase) frequency response. There are two types of EQ files, pole-zero files, which contain a set of s-plane poles and zeros...
Page 307 Specifies the overall multiplier for this transfer function. A number of EQ files are supplied with SR1. By examining these files and using the information given above it should be possible to synthesize new EQ files corresponding to any pole-zero type transfer function.
Page 308 SR1 digitizer files are two-column ASCII text files. The first column displays time, which increases monotonically in intervals of the sampling period. For digitizer files created by SR1's optional digitizer the sampling period is always 12.5 ns (80 MHz). However, it is possible to create files with different sampling rates and import them into the digitizer for display and analysis.
Page 309 8.0000000e-004 9.0000000e-004 Multiple (tab-separated) columns of values may be present in the file. If so, SR1 will prompt the user for the correct column to use when loading the arbitrary waveform file. Note that the absolute value of the sample values are disregarded when outputting an arbitrary waveform, only the relative magnitudes of the sample values are important.
Page 310: Hardware Reference
1024x768 resolution. If SR1 is equipped with the standard VGA (640x480) display then the external monitor can be run either in VGA mode or in XGA mode. If a VGA SR1 is operated with an external monitor in XGA mode, the front panel LCD display will no longer show the entire screen but instead will show a 640x480 portion of the screen that will pan as the mouse is moved.
Page 311 4. Install one bracket on the right side of the unit using two 10-32 x 1/2” truss head screws. Install the other bracket on the left side of the unit with the washers between the bracket and SR1 using two 10- 32 x 1/2”...
Page 312: Index
SR1 Operation Manual v2 Colors Index Analog Colors Digital Colors Common Analyzer Features Common Mode Sine - A - Computer Functions Confidence Abitrary Configuration Files 28, 29, 30, 31 About SR1 Constant (Offset) AES Reference 105, 293 Controls Amplitude Units...
Page 313 Index Digitizer Display Eye Diagrams - F - Eye Limits Probability Tab 127, 141 Spectrum FFT (Dual Ch.) Speedbar FFT Analyzer (1 Ch.) Time Record Tab FFT Chirp 43, 62 FFT1 Analyzer DIM/TIM 161, 267 Aliasing Displays Averaging Bar Chart Bandwidth Digitizer Display Block Diagram...
Page 314 SR1 Operation Manual v2 Range Generator, Analog Amplitude Controls Sample Rate Maximum Output Limit Scaling Mono-Stereo Selection Size Output Configuration Panel - I - Sampling Rate Units IEEE-488 Waveforms Setting Address Generator, Digital Audio Adding Waveforms IMD Analyzer Amplitude Controls...
Page 315 Index - K - - O - Keyboard Octave Anallyzer Panel Keyboard and Mouse Ports Keypad Octave Analyzer Averaging Knob 13, 291 Mode Selection - L - Optional Filters 76, 305 Output Impairment Limit Testing Overview Line Voltage Selector Load Configuration - P - Load Displays Lock...
Page 316 SR1 Operation Manual v2 Quick Measurements SMPTE/DIN 62, 161, 267 Reference Reports Software Updates Setup Speaker Specifications THD+N Square Wave 43, 62 Quick Measurments SR1 Basic Interchannel Phase Actions Properties Quick Start SR10 - R - SR11 SR12 SRS Contact Information...
Page 317 218, 241 - W - Weighting Filters - X - XLR Connector Distribution in the UK & Ireland Lambda Photometrics Limited Lambda House Batford Mill Harpenden Herts AL5 5BZ United Kingdom info@lambdaphoto.co.uk W: www.lambdaphoto.co.uk +44 (0)1582 764334 +44 (0)1582 712084...

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