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Digital Audio Corporation PCAP II User Manual

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PCAP II
PERSONAL COMPUTER AUDIO
PROCESSOR
USER'S MANUAL
DIGITAL AUDIO CORPORATION
A DRI COMPANY

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  • Page 1 PCAP II PERSONAL COMPUTER AUDIO PROCESSOR USER’S MANUAL DIGITAL AUDIO CORPORATION A DRI COMPANY...
  • Page 3 User’s Manual November 2, 1999 Version 12.0 DIGITAL AUDIO CORPORATION A DRI COMPANY 5121 Holly Ridge Drive Raleigh, NC 27612 Phone: 919 782 6767 Fax: 919 782 6766 sales@dacaudio.com www.dacaudio.com Copyright © 2000 by Digital Audio Corporation. All rights reserved.

  • Page 5: Table Of Contents

    3.1 Fast Start ..............10 3.2 PCAP II Tutorial............14 3.3 Training CD Recordings ..........31 4 . PCAP II SOFTWARE REFERENCE MANUAL....33 4.1 Master Control Panel ........... 34 4.2 Input and Output Processors ........38 4.2.1 Input and Output Highpass Filters (HPFs) ....38 4.2.2 Digitally-Controlled Limiter ........
  • Page 6 5 . OPERATING PCAP II STAND-ALONE ......140 6 . PCAP II CUSTOMIZATION OPTIONS ......143 6.1 Configuring PCAP II for Different COM Ports ....143 6.2 Configuring PCAP II for Different Baud Rates ....145 6.3 Customizing Screen Colors......... 148...
  • Page 7 Figure 1-2 PCAP II Functional Block Diagram..........4 Figure 1-3 PCAP II Front Panel..............5 Figure 1-4 PCAP II Rear Panel..............6 Figure 2-1 PCAP II Master Control Icon ............9 Figure 2-2 Master Control Panel..............9 Figure 3-1 PCAP II Connection Diagram...........11 Figure 3-2 Fast Start File Pulldown Menu ..........12 Figure 3-3 Fast Start Open Setup File Window ........12...
  • Page 8 Figure 4-19 Bandstop Filter Control Window ...........65 Figure 4-20 Bandstop Filter Graphical Description ........66 Figure 4-21 Comb Filter Control Window ..........67 Figure 4-22 Comb Filter Graphical Description........70 Figure 4-23 Notch Filter Control Window..........71 Figure 4-24 Notch Filter Graphical Description ........72 Figure 4-25 Multiple Notch Filter Control Window........74 Figure 4-26 Multiple Notch Filter Graphical Description ......75 Figure 4-27 Slot Filter Control Window............77...
  • Page 9 Figure 4-65 Report-Generator Pulldown Menu........138 Figure 4-66 Help Pulldown Menu ............139 Figure 6-1 ComPort Selection Menu............143 Figure 6-2 Baud Rate Selection Menu............ 146...

  • Page 10: Acknowledgement

    ACKNOWLEDGEMENT The Personal Computer Audio Processor, model PCAP II, is a second generation PC-based digital audio filtering system. Like its predecessor, the Personal Computer Digital Filter, this product was inspired by and significantly contributed to by Mr. James P. Foye of the United States Postal Service.

  • Page 11: Foreword

    It attacks a wide variety of noises in forensic applications. Body microphone, cassette, microcassette, telephone, broadcast, and hi-fi audio signals can all be processed efficiently, since the PCAP II can be set to operate at bandwidths of 3.2, 5.4, 6.5, 8.0, 11, and 16 kHz.
  • Page 12 The PCAP II is designed to replace an entire rack of audio processing equipment. With monophonic signals, as many as nine sequential stages of processing (five of which are digital) can be performed simultaneously. With stereo signals, seven sequential stages of stereo processing (three of which are digital) for each channel are also available.

  • Page 13: System Basics

    Computer Headphones Figure 1-1 PCAP II System Configuration The PCAP II Master Control program is written to be run on any Microsoft Windows 95/98/NT IBM PC-compatible computer. For best performance the following minimum system is recommended: Intel Pentium CPU processor (at least 166 MHz) 32 Megabytes of RAM 2.1 GB hard disk drive...

  • Page 15: External Processor Capability

    1.2 External Processor Capability The PCAP II EXTERNAL PROCESSOR unit is a high-performance, self-contained digital signal processor and contains 27 DSP microprocessors, which are allocated as follows: Sixteen FIR filter processors which can be configured as 1, 2, 3, or 4 independent audio processors.

  • Page 16: External Processor Front Panel

    Ten stand-alone nonvolatile memories are provided for onboard storage and recall of filter setups created by the PCAP II Master Control Program. This allows the external processor to be operated in any of four previously-stored setups without being connected to a For a simplified functional block diagram, see Figure 1-2.

  • Page 17: External Processor Rear Panel

    For complete instructions on using the STAND- ALONE memories, see Sections 4.8.4 and 5.0. The front panel of the PCAP II external processor appears as follows (Figure 1-3): Figure 1-3 PCAP II Front Panel The LEFT and RIGHT INPUT LEVEL controls allow the user to adjust the input signals to the proper level for processing.

  • Page 18: Figure 1-4 Pcap Ii Rear Panel

    18 VDC source. The POWER switch must be switched to the ON position in order for the unit to operate. A 9-pin RS232 jack is provided to connect the PCAP II external processor to a computer using the supplied cable. In this new version...

  • Page 19: Installation Instructions

    2. INSTALLATION INSTRUCTIONS 2.1 Cautions to User To install the PCAP II hardware and software, the user must have a good working knowledge of IBM PC-compatible computers and the Microsoft Windows operating environment. Particularly, the user must know which RS232 COM ports are COM1, COM2, COM3, etc.
  • Page 20 If not, use the Run command in the Windows Start menu to start the installation program. If the machine you wish to install the PCAP II Master Control Software does not have a CD-ROM then, on a machine that does have a CD-ROM, insert the CD and run Windows Explorer.

  • Page 21: Figure 2-1 Pcap Ii Master Control Icon

    If you know to which COM port the PCAP II external processor is connected, configure the PCAP II Master Control program for the correct COM port by following the procedure in Section 6.1. The PCAP II system should now be installed and ready to run.

  • Page 22: Getting Started

    Connect the LEFT and RIGHT channel line-level audio outputs (AUDIO OUT jacks) of your Source Audio Player to the LEFT IN and RIGHT IN RCA jacks on the PCAP II external processor rear panel as shown in Figure 3-1. Note that the RIGHT IN signal is only used in stereo configuration and with the 2CH Adaptive Filter in mono configuration.

  • Page 23: Figure 3-1 Pcap Ii Connection Diagram

    LEVEL for comfortable listening. NOTE: If you wish to listen to the unprocessed audio going into the PCAP II, toggle the MONITOR switch on the PCAP II external processor to INPUT. To listen to the PCAP II output, toggle the MONITOR switch to OUTPUT.

  • Page 24: Figure 3-2 Fast Start File Pulldown Menu

    Figure 3-3: Figure 3-3 Fast Start Open Setup File Window The Setup Files box should contain a list of all PCAP II setup files on your hard disk. The installation procedure in Section 2.2 should have installed several setup files which...

  • Page 25: Figure 3-4 Fast Start Recall Setup Alert Message

    Click on OK to commence the opening (recall) of the setup file. An "hourglass" mouse cursor will now appear, indicating that the PCAP II is busy recalling a setup file. When the mouse cursor returns to normal, the setup file will be complete.

  • Page 26: Pcap Ii Tutorial

    3.2 PCAP II Tutorial This brief tutorial should allow the user to quickly learn the basic operation of the PCAP II 's controls. It should require about 1 hour to complete, yet it demonstrates the basic functionality. NOTE: A subset of the PCAP II's functions are utilized in this tutorial.
  • Page 27 Connect the LEFT and RIGHT outputs (AUDIO OUT jacks) of the audio player to the LEFT and RIGHT ANALOG INPUTS jacks on the PCAP II external processor; make sure that the INPUT SELECT switch is set to ANALOG. Insert the PCAP II Training Tape and rewind to the beginning.
  • Page 28 Filter 2 block until both buttons indicate Filter Out (bypassed). Click on the Equalizer button in the Equalizer block until the button indicates Equalizer Out (bypassed). Switch the MONITOR switches on the PCAP II external processor OUTPUT/LEFT/RIGHT. Readjust headphone VOLUME if necessary.

  • Page 29: Figure 3-6 Tutorial Limiter Setup Window

    INPUT LEVELS controls fully clockwise to the MAX position. This should cause the PCAP II audio inputs to overload (this will not damage the unit but will distort the audio). The tricolor level LED should indicate RED on peaks, and the Left bargraph in the Input Levels block should be frequently popping up into the RED zone, indicating overload.

  • Page 30: Figure 3-7 Tutorial Agc Setup Window

    improve whenever the button indicates Limiter In. The input limiter is electronically lowering the INPUT LEVELS to avoid overload. Restore the button to the Limiter Out position and restore the INPUT LEVELS controls to normal level. Click on the AGC Setup button in the Output Levels block. The following window (Figure 3-7) will appear: Figure 3-7 Tutorial AGC Setup Window Use the mouse to set the Release Time to 200 milliseconds...

  • Page 31: Figure 3-8 Tutorial Filter Selection Window

    Click on the Select button in the Filter 1 block. A window similar to the one in Figure 3-8 will appear. Use the mouse to click on 1CH Adaptive, then OK*. The Filter 1 block should now indicate that the selected mode is 1CH Adaptive. Figure 3-8 Tutorial Filter Selection Window Click on the Select button in the Filter 2 block and select Lowpass.

  • Page 32: Figure 3-9 Tutorial 1Ch Adaptive Filter Control Window

    Figure 3-10 will appear: ___________________________________ *Scroll bars are used throughout the PCAP II to adjust various filter parameters. Drag the scroll box "slider" or click within the scroll bar to make coarse adjustments. Click on the scroll arrows on either end of the scroll bar to make fine adjustments.

  • Page 33: Figure 3-10 Tutorial Lowpass Filter Control Window

    Figure 3-10 Tutorial Lowpass Filter Control Window This is the Lowpass Filter Control Window. It is used to select Cutoff Frequency, Stopband Attenuation, Transition Slope. Use the mouse to set all controls to match the settings shown in Figure 3-10. Do not click on the OK button at this time.

  • Page 34: Figure 3-11 Tutorial Equalizer Selection Window

    Use the mouse to click (try double clicking to avoid clicking on OK) on 20-Band Graphic. The Equalizer block should now indicate that the selected mode is 20-Band Graphic. Click on the Control button in the Equalizer block. window in Figure 3-12 will appear. Figure 3-11 Tutorial Equalizer Selection Window This is the 20-Band Graphic Equalizer Control Window.

  • Page 35: Figure 3-13 Tutorial Store 20-Band Graphic Equalizer Window

    Click on the Store button to bring up the Store 20-Band Graphic Equalizer window as in Figure 3-13. Click on the 1 button to store your slider settings in Memory 1*. (We will recall these settings later.) Once you have clicked this button, the system will automatically return to the 20-Band Graphic Equalizer control window.

  • Page 36: Figure 3-14 Tutorial Recall 20-Band Graphic Equalizer Window

    dB.) Click on the Normalize button and see how all the sliders will instantly move up together so that the highest slider is exactly 0dB. (Once the equalizer is adjusted, it should be normalized to minimize signal loss.) Click on the Make All 0dB button to instantly set all the sliders to the 0dB position.

  • Page 37: Figure 3-15 Tutorial Spectrum Analyzer Window

    Click on the Clear button in the Averager block; both spectrum waveforms should now be cleared ___________________________________ *The spectral analysis freezes immediately; however, the display will briefly continue to update as remaining data is read from the PCAP II external processor.
  • Page 38 completely away. Restore the Run/Freeze button to the Run indication to allow the spectrum waveform to resume responding to the input signal. Click the mouse anywhere on the spectral waveforms to move the vertical red marker to that point. A readout of frequency (Freq:) and magnitude (Mag:) of the Yellow and Blue traces will be indicated below the display grid.

  • Page 39: Figure 3-16 Tutorial Display Select Window

    Lowpass filter. Adjust any of the Lowpass filter controls, noting the effect on the Blue trace* . Click on the OK button in the Lowpass window to return to the Master Control Panel. To return to the Spectrum Analyzer display, click on View in the menu bar to bring up the Display Select window as shown in Figure 3-16.

  • Page 40: Figure 3-18 Tutorial Save Setup File Window

    Click on Save Setup File to bring up the Save Setup File window as shown in Figure 3-18. For now, do not change the Drives or Directories settings; just keep in mind that you could change these settings to allow setup files to be stored to any directory of any drive. Figure 3-18 Tutorial Save Setup File Window Click your mouse cursor on the Description text box, which should currently contain the word Unnamed.

  • Page 41: Figure 3-19 Tutorial Store In File Name Text Box

    Figure 3-19 Tutorial Store in File Name Text Box Click on OK to store your first setup file and return to the Master Control Panel. Click on File to access the File Pulldown Menu as in step 56. Click on Open Setup File to bring up the Open Setup File window similar to Figure 3-3, but with mysetup.dac added to the Setup Files list.

  • Page 42: Figure 3-20 Tutorial Report Generator Pulldown Menu

    Master Control Panel. Figure 3-20 Tutorial Report Generator Pulldown Menu This completes the PCAP II Tutorial. Please feel free at this point to experiment with the on-screen filter settings. Remember you can always recall filter settings that will likely work using the Open Setup File feature.

  • Page 43: Training Cd Recordings

    3.3 Training CD Recordings The PCAP II Training CD supplied with the PCAP II is a useful training tool. Each of its 13 noise sample recordings is accompanied by a suggested Setup File, installed on your comptuer along with the other PCAP II software by the installation procedure.
  • Page 44 Filter cannot separate voices (spoken or sung) but does reduce muffling 23:25 Interview and argument s12.dac 25:50 Radio/TV s13.dac 2CH adaptive (Ref Canceller) filtering using a reference. Cancellation limited by analog tape recorder's wow/flutter Tabel 3.1 PCAP II Training CD Summary...

  • Page 45: Pcap Ii Software Reference Manual

    This portion of the user's manual is designed as a reference guide to which the user may refer for more detailed information on specific windows in the PCAP II Master Control program. It is assumed in this section that the user has a good working knowledge of Microsoft Windows, has properly installed the PCAP II hardware and software using the installation instructions in Section 2.2, and has completed...

  • Page 46: Master Control Panel

    4.1 Master Control Panel When the PCAP II Master Control program is run from Microsoft Windows, the Master Control Panel appears. The Master Control Panel features are shown in Figure 4-1. From this screen, all external processor capabilities can be accessed.
  • Page 47 Configuration Selects mono or stereo filter configurations. Mono Block**: configuration allows the user to enhance a single input signal with as many as five successive stages of digital signal processing. Stereo, Linked configuration allows the user to process two input signals simultaneously with as many as three stages of digital signal processing;...
  • Page 48 Equalizer Used to control each equalizer stage. In Mono and Block(s): Stereo, Linked configurations, one equalizer block will be displayed. In Stereo, Indep. configuration, a separate equalizer block will be displayed for each channel. Select the type of equalizer to be implemented by using the Select button to pull up the equalizer selection window (See Section 4.3.2 Equalizer Selection Window.) Set up the selected...
  • Page 49 Output Levels Used to view output signal levels via bargraph Block: display, switch Output HPFs In and Out of the process, switch output automatic gain controls (AGCs) In and Out of the process, and to setup AGC parameters. See Section 4.2.1 for further details on the Output HPFs and AGCs Status Box: Used to indicate RS232 COM port.

  • Page 50: Input And Output Processors

    4.2 Input and Output Processors 4.2.1 Input and Output Highpass Filters (HPFs) Application: The Input HPFs are used to remove rumble or other low- frequency noises which occur below 100 Hz to 500 Hz (adjustable) from the input signals before they enter the digital processors.

  • Page 51: Figure 4-3 Input Hpf Setup Window

    For fast access to the Input and Output HPFs, pressing <Alt-I> or <Alt-O> may also be used to toggle the Input or Output HPFs, respectively, in or out of the process. Adjustment of the Input HPF cutoff frequency is accomplished by clicking on the IHPF Setup button.

  • Page 52: Digitally-Controlled Limiter

    4.2.2 Digitally-Controlled Limiter Application: The four-channel input Limiter automatically protects the input circuits from overload distortion by reducing input signal levels whenever loud sounds, such as door slams, exceed a specified Threshold. When the overload goes away, the Limiter returns the input signal levels to their original settings over the specified Release Time interval.

  • Page 53: Figure 4-5 Limiter Setup Window

    Time options are 0.125 seconds (fastest), 0.250 seconds, 0.500 seconds, and 1.0 seconds (slowest). The 0.250 seconds setting is recommended for voice applications. Release Time settings longer than 0.250 seconds may result in excessively long periods of reduced signal level after an overload occurs. Figure 4-5 Limiter Setup Window Threshold specifies the input bargraph level which is considered to be an overload condition;...

  • Page 54: Digitally-Controlled Agc

    4.2.3 Digitally-Controlled AGC Application: The dual output Automatic Gain Control automatically attempts to boost low-level output signals to a peak reference level (-18dB bargraph level) by gradually increasing output signal gain over a specified Release Time interval until either the proper level or Maximum Gain has been reached. This compensates for near party/far party conversations and for losses in signal level which may have occurred during the enhancement process.

  • Page 55: Figure 4-7 Agc Setup Window

    Figure 4-7 AGC Setup Window When the AGC Setup button is pressed. The window in Figure 4-7 will appear. This window allows the user to adjust the Release Time, Maximum Gain, and Link settings of the AGC. Release Time specifies how quickly the AGC will react to decreases in output signal level.

  • Page 56: Dsp Processor Selection

    4.3 DSP Processor Selection 4.3.1 Filter Selection Window Clicking the Select button in any Filter block (not an Equalizer block) causes the following window (Figure 4-8) to appear. Figure 4-8 Filter Selection Window Click the mouse on the desired filter type then click on OK (or, simply double-click the desired filter type) to select it for the current Filter block.

  • Page 57: Figure 4-9 Filter Select Combo Box

    Figure 4-9 Filter Select Combo Box Clicking the Control button in any Filter block causes the control window for the selected filter type to appear. See Section 4.4 for detailed information on control windows for each filter type.

  • Page 58: Equalizer Selection Window

    4.3.2 Equalizer Selection Window The last DSP stage is always an Equalizer stage. Clicking the Select button for any Equalizer block (not a Filter block) causes the following window (Figure 4-10) to appear. Click the mouse on the desired equalizer type then click on OK (or, simply double-click the desired equalizer type) to select it for the current Equalizer block.

  • Page 59: Dsp Filter Control Windows

    4.4 DSP Filter Control Windows This section provides detailed description of the control window for each filter mode. For any DSP Filter block, the control window for the selected filter is accessed by clicking on the Control button. 4.4.1 2CH Adaptive Filter Application: The 2CH Adaptive filter is used to automatically cancel from the Primary (Left) input any audio which matches the...
  • Page 60 This can be very useful in situations where there are pauses, or breaks, in the speech being processed. Hint: Conditional adaptation is useful in maintaining adaptation once the filter has converged. Motion in the room and air temperature changes affect filters operation.
  • Page 61 adaptation.* As a rule set this rate to maximum initially, to establish convergence, then back off to a mid value to maintain cancellation. Delay Channel: Specifies whether the delay line is to go into either the Primary (Left) channel or the Reference (Right) channel.
  • Page 62 modified Reference signal being subtracted from the Primary signal. Filter Button: Used to switch the 2CH Adaptive filter in and out of the process without affecting the other filters in the process. Button indicates Filter In when the filter is in the process, or Filter Out when the filter is out of the process.

  • Page 63: 1Ch Adaptive Filter

    4.4.2 1CH Adaptive Filter Application: The 1CH Adaptive filter is used to automatically cancel predictable and convolutional noises from the input audio. Predictable noises include tones, hum, buzz, engine/motor noise, and, to some degree, music. Convolutional noises include echoes, reverberations, and room acoustics. Figure 4-12 1CH Adaptive Filter Control Window Description of controls (Figure 4-12) is as follows: Conditional...
  • Page 64 the observed dB level. Click on the Clear button if you desire the filter to completely readapt based upon the new Conditional Adaptation settings. The Master Control Panel will display an Adapting indicator for each filter block whenever Filter will adapt is set to anything other than Always.
  • Page 65 Prediction Span: Sets the number of samples in the prediction span delay line. Prediction span indicated both samples milliseconds, and can be adjusted from 1 to 10 samples. Shorter prediction spans allow maximum noise removal, while longer prediction spans preserve voice naturalness and quality.

  • Page 66: Lowpass Filter

    4.4.3 Lowpass Filter Application: The Lowpass filter is used to decrease the energy level (lower the volume) of all signal frequencies above a specified Cutoff Frequency, thus reducing high-frequency noises, such as tape hiss, from the input audio. The Lowpass filter is sometimes called a "hiss filter."...
  • Page 67 Description of controls is as follows: Cutoff Specifies frequency in Hertz above which all Frequency: signals are attenuated. Frequencies below this cutoff are unaffected. Minimum Cutoff Frequency is 100 Hz, while the maximum Cutoff Frequency depends upon the System Bandwidth setting. Cutoff Frequency can be adjusted in 1 Hz steps.

  • Page 68: Figure 4-14 Lowpass Filter Graphical Description

    Figure 4-14 Lowpass Filter Graphical Description...

  • Page 69: Highpass Filter

    4.4.4 Highpass Filter Application: The Highpass filter is used to decrease the energy level (lower the volume) of all signal frequencies below a specified Cutoff Frequency, thus reducing low-frequency noises, such as tape or acoustic room rumble, from the input audio (The Highpass filter is sometimes called a "rumble filter").
  • Page 70 Cutoff Frequency: Specifies frequency in Hertz below which all signals are attenuated. Frequencies above this cutoff are unaffected. Minimum Cutoff Frequency frequencies attenuated), while the maximum Cutoff Frequency depends upon System Bandwidth setting. Cutoff Frequency can be adjusted in 1 Hz steps Stopband Specifies amount in dB by which frequencies Attenuation:...

  • Page 71: Figure 4-16 Highpass Filter Graphical Description

    Figure 4-16 Highpass Filter Graphical Description...

  • Page 72: Bandpass Filter

    4.4.5 Bandpass Filter Application: The Bandpass filter is used to decrease the energy level (lower the volume) of all signal frequencies below a specified Lower Cutoff Frequency and above a specified Upper Cutoff Frequency, thus combining the functions of a seriesed Lowpass and Highpass filter into a single filter.

  • Page 73: Figure 4-17 Bandpass Filter Control Window

    Figure 4-17 Bandpass Filter Control Window Description of controls is as follows: Lower Cutoff Specifies frequency in Hertz below which all Frequency: signals attenuated. Frequencies between this cutoff and the Upper Cutoff Frequency are unaffected. Minimum Lower Cutoff Frequency is 0 Hz, while the maximum Lower Cutoff Frequency is 10 Hz below the Upper Cutoff Frequency.
  • Page 74 Transition Slope: Specifies slope at which frequencies below the Lower Cutoff Frequency and above the Upper Cutoff Frequency are attenuated in dB per octave. Sharpest attenuation occurs when Transition Slope is set to maximum, while gentlest attenuation occurs when Transition Slope is set to minimum. Note that the indicated value changes depending upon Cutoff Frequency, System Bandwidth, Configuration, and Number DSP Stages...

  • Page 75: Figure 4-18 Bandpass Filter Graphical Description

    Figure 4-18 Bandpass Filter Graphical Description...

  • Page 76: Bandstop Filter

    4.4.6 Bandstop Filter Application: The Bandstop filter is used to decrease the energy level (lower the volume) of all signal frequencies above a specified Lower Cutoff Frequency and below a specified Upper Cutoff Frequency. The signal region between the Lower Cutoff Frequency and the Upper Cutoff Frequency is called the stopband region.

  • Page 77: Figure 4-19 Bandstop Filter Control Window

    Figure 4-19 Bandstop Filter Control Window Upper Cutoff Specifies frequency in Hertz above which no Frequency: signals attenuated. Frequencies between this cutoff and the Lower Cutoff Frequency are attenuated. Minimum Upper Cutoff Frequency is 10 Hz above the Lower Cutoff Frequency, while the maximum Upper Cutoff Frequency depends upon the System Bandwidth setting.

  • Page 78: Figure 4-20 Bandstop Filter Graphical Description

    frequency width of an octave is proportional to Cutoff Frequency. Stopband Specifies amount in dB by which frequencies Attenuation: above the Lower Cutoff Frequency and below the Upper Cutoff Frequency are attenuated. Stopband attenuation is adjustable from 10dB to 60dB in 1 dB steps. Filter Button: Used to switch the Bandstop filter in and out of the process without affecting the other...

  • Page 79: Comb Filter

    4.4.7 Comb Filter Application: The Comb filter is used to remove, or "notch out", harmonically related noises (noises which have exactly equally-spaced frequency components), such as power-line hum, constant-speed motor/generator noises, etc., from the input audio. The filter response consists of a series of equally-spaced notches which resemble a hair comb, hence the name "Comb filter".
  • Page 80 Comb Frequency: Specifies fundamental frequency in Hertz of comb filter. Notches are generated at multiples, or harmonics, of this frequency. NOTE: Comb Frequency changes whenever the System Bandwidth setting is altered; if you change the System Bandwidth setting, will need readjust Comb Frequency for any Comb Filters selected.
  • Page 81 All. Next adjust the Comb Frequency to achieve maximum hum removal; normally this will be in the vicinity of 60 or 50 Hz. (Analog recordings will seldom be exactly 5 0 or 60 Hz due to tape speed errors. Next, adjust the Notch Limit down in frequency until the hum is bearly heard, then increase it 100 Hz.

  • Page 82: Notch Filter

    Figure 4-22 Comb Filter Graphical Description 4.4.8 Notch Filter Application: The Notch filter is used to remove, or "notch out", a narrow- band noise, such as a tone or a whistle, from the input audio with minimal effect to the remaining audio. The Notch filter works best with stable noise sources which have constant frequency;...

  • Page 83: Figure 4-23 Notch Filter Control Window

    the Spectrum Analyzer window. See Section 4.6.3 for complete instructions on operating the Spectrum Analyzer window. Initially set the Notch Depth to 60 dB and the Notch Width to the narrowest possible value. Next, set the Notch Frequency to the noise frequency. Fine adjustment of the Notch Frequency may be necessary to place the notch precisely on top of the noise signal and achieve maximum reduction of the...

  • Page 84: Figure 4-24 Notch Filter Graphical Description

    Notch Depth: Depth of the notch that is generated. Notch Depth is adjustable from 10 dB to 60 dB in 1 dB steps. Notch Width: Width of the generated notch in Hertz. NOTE: Minimum Notch Width varies with System Bandwidth, Configuration, Number DSP Stages.

  • Page 85: Multiple Notch Filter

    This is accomplished using a frequency-sampling- synthesized 1024-tap FIR filter which is calculated in the PC by the PCAP II Master Control program. The Multiple Notch filter, unlike the Notch filter, is able to tolerate moderate wow and flutter variances in the frequency of a noise source; if the frequency of a noise source varies excessively, then the 1CH Adaptive filter is recommended.

  • Page 86: Figure 4-25 Multiple Notch Filter Control Window

    Figure 4-25 Multiple Notch Filter Control Window Description of controls is as follows: Notch Freq (1-16): Specifies frequency in Hertz which is to be removed from the input audio by each of the 16 notches. Minimum Notch Freq is 1 Hz, while maximum Notch Freq depends upon the System Bandwidth setting.

  • Page 87: Figure 4-26 Multiple Notch Filter Graphical Description

    Destroy Button: Clears all Notch Freq and Notch Width settings for all 16 notches and restores the Multiple Notch filter coefficients to an allpass filter (no notches). Control Button: The Multiple Notch control window is only capable of displaying the settings for eight notches at a time;...

  • Page 88: Slot Filter

    4.4.10 Slot Filter Application: The Slot filter is used to isolate, or "slot", a single-frequency signal, such as a tone or a whistle, in the input audio, attenuating all other audio. This is the exact opposite of the Notch filter function. To properly utilize the Slot filter, you will first need to identify the frequency of the signal to be isolated;...

  • Page 89: Figure 4-27 Slot Filter Control Window

    Figure 4-27 Slot Filter Control Window Description of controls is as follows: Slot Frequency: Specifies frequency in Hertz which is to be enhanced in the input audio. Minimum Slot Frequency is 10 Hz, while maximum Slot Frequency depends upon System Bandwidth setting.

  • Page 90: Figure 4-28 Slot Filter Graphical Description

    Figure 4-28 Slot Filter Graphical Description...

  • Page 91: Multiple Slot Filter

    Multiple Notch filter function, and is accomplished using a frequency-sampling-synthesized 1024- tap FIR filter which is calculated in the PC by the PCAP II Master Control program. To properly utilize the Multiple Slot filter, you will first need to identify the frequencies of all signals to be isolated;...

  • Page 92: Figure 4-29. Multiple Slot Filter Control Window

    Figure 4-29. Multiple Slot Filter Control Window Description of controls is as follows: Slot Freq (1-16): Specifies frequency in Hertz which is to be isolated from the input audio by each of the 16 slots. Minimum Slot Freq is 1 Hz, while maximum Slot Freq depends upon the System Bandwidth setting.

  • Page 93: Figure 4-30 Multiple Slot Filter Graphical Description

    or Number DSP Stages in order to rebuild the filter. Destroy Button: Clears all Slot Freq and Slot Width settings for all 16 notches and restores the Multiple Slot filter coefficients to an allpass filter (no slots). Control Button: The Multiple Slot control window is only capable of displaying the settings for eight slots at a time;...

  • Page 94: Spectral Inverse Filter

    4.4.12 Spectral Inverse Filter Application: The Spectral Inverse Filter (SIF) is an equalization filter which automatically readjusts the spectrum to reduce noise and muffling effects. It is especially useful when the voice has been exposed to reverberations and bandlimited noises. SIF measures the signal’s spectrum and uses this information to implement a high-resolution digital filter for correcting spectral irregularities and reduce added noises.

  • Page 95: Figure 4-31 Basic Process Of Spectral Inverse Filter

    Figure 4-31 Basic Process of Spectral Inverse Filter The equalization effect of SIF is very beneficial with reverberant audio and recordings exposed to substantial recorder wow and flutter. The noise sources must remain stationary for SIF to be effective. SIF cannot readjust itself to changing noises, such as music.

  • Page 96: Figure 4-32 Sif Control Window When Equalize Voice Selected

    Figure 4-32 SIF Control Window When Equalize Voice Selected Description of controls/indicators is as follows: Filter Used to display the original audio spectrum Input Display: (Yellow Trace = Filter) and the spectral inverse filter curve (Blue Trace = Filter Shape). For each trace, 460 spectral lines and 70dB of dynamic range are displayed.
  • Page 97 Run/Freeze button which allows the user to start (Run indication) or stop (Freeze indication) update of the averaged spectrum. Num Averages setting which allows the user to specify the degree of smoothing of the original audio power spectrum. For minimum smoothing, set to 1;...
  • Page 98 inverse filter within the specified frequency limits; this may be set to the approximate difference in amplitude between the largest and smallest input spectral components within the frequency limits. Maximum Range is 50dB. NOTE: Maximum Range should only be used when necessary;...

  • Page 99: Figure 4-33 Sif Control Window When Attack Noise Selected

    Figure 4-33 SIF Control Window When Attack Noise Selected Lower and For EQ Voice operation, specifies Lower Upper Voice Limit and Upper Voice Limit. These Frequency are the lower and upper frequency limits over Limits: which the input voice audio is equalized. Audio o utside these limits is rolled off and ultimately attenuated by 40dB.
  • Page 100 To set the upper and lower frequency limits, use the horizontal scroll bars to position the two red markers on the Filter Display to the desired frequency positions. NOTE: You must use the scroll bars; you cannot click the mouse at the desired points in the Filter Display area.

  • Page 101: Figure 4-34 Spectral Inverse Filter Store Window

    Filter Button: Used to switch the Spectral Inverse filter in and out of the process without affecting the other filters in the process. Button indicates Filter In when the filter is in the process, or Filter Out when the filter is out of the process.

  • Page 102: Figure 4-35 Spectral Inverse Filter Recall Window

    be stored in that disk memory for the current System Bandwidth. Recall Button: This button allows the user to recall a previously stored spectral inverse filter curve from one of 11 disk memories for the currently selected System Bandwidth. Clicking this button brings up the window in Figure 4-35.

  • Page 103: Figure 4-36 Eq Voice Operation, Eq Range Set To 10Db, Output Shape Set To Flat

    only the peaks in the spectrum are flattened. As the Range is increased, lower energy segments are equalized. The top trace in each of the figures below gives the filter curve and the bottom trace gives the original input spectrum. In Figure 4-36, Figure 4-37, and Figure 4-38 the EQ Range is increased.
  • Page 105 The Output spectral Shape may be selected as Flat, illustrated in Figure 4-36, Figure 4-37, and Figure 4-38, above. It may also be set to Voice or Pink. See Figure 4-40. The Attack Noise mode does not attenuate Out-of-Limits signal, but equalizes and attenuates in-Limits signal frequencies.

  • Page 106: Figure 4-38 Sif With Eq Range Set To 50Db

    Figure 4-38 SIF with EQ Range set to 50dB Try to capture a representative spectrum using the Freeze/Run button. Once a stable, representative spectrum is obtained on the display, Freeze the analyzer. This same spectrum may be used for several different variations of the filter (changing Limits or Range, as an example).

  • Page 107: Figure 4-39 Attack Noise Operation, Attack Range Set To 30Db

    SIFs. (The PCAP II will series up to four). The audio outside those limits is unfiltered. Range and Gain: SIF is a spectral attenuator. The spectral peaks are pressed down toward the spectral valleys. The amount of reduction is limited by the Range scroll bar. If, however, all peaks are reduced to the lowest valley, no more reduction takes place.

  • Page 108: Figure 4-40 Sif With Output Shape Set To Voice

    Output Shape: Three output spectral shapes are selectable by the user. The Flat shape requires the SIF to produce a uniform (to the degree possible) long-term output spectrum. This can be subsequently reshaped by the Hi-Res Graphic Filter or Output Equalizer to a more natural-sounding spectrum.

  • Page 109: Hi-Res Graphic Filter

    Once the filter shape has been drawn, a linear-phase digital filter is constructed in the PC and transferred to the external PCAP II unit. The Edit feature allows the user to make readjustments to...

  • Page 111: Figure 4-42 Hi-Res Filter Store Window

    Description of controls/indicators is as follows: Filter Display: Graphically displays the current shape of the filter. Also used in conjunction with the mouse to draw a new filter shape or to edit an existing one (see New, Edit, and Normalize button descriptions). A grid is provided to assist the user in visually judging frequency and attenuation at any point in the display.

  • Page 112: Figure 4-43 Hi-Res Graphic Filter Recall Window

    Clicking one of the 10 "jukebox-style" buttons will cause the current filter curve to be stored in that disk memory for the current System Bandwidth. Clicking the Cancel button exits the Store window without storing the filter curve in any of the memories. Recall Button: This button allows the user to recall a previously stored filter curve from one of 11...

  • Page 113: Figure 4-44 New Hi-Res Graphic Filter Display

    From the PCAP II Master Control Panel, set System Bandwidth to 5.4 kHz, Configuration to Mono, and Number DSP Stages to 2. Click on the Select button in the Filter 1 block, then select Hi-Res Graphic from the selection window.

  • Page 114: Figure 4-45 Hi-Res Graphic Draw In Progress

    frequencies and attenuations. When the mouse click button is released, a line segment will be drawn from the last defined point on the curve to the current mouse cursor position. For this example, placing points at precise frequencies and attenuations is not required; draw the curve approximately as shown in Figure 4-45 using mouse clicks.

  • Page 115: Figure 4-47 Hi-Res Graphic Edit Window

    When you have drawn the last point (must be at or beyond the right edge of the filter display area), the mouse cursor will change to an "hourglass" shape for a few seconds while the filter is being calculated. When the calculations are complete, the mouse cursor and the buttons in the Hi-Res Graphic control window will return to normal appearance.

  • Page 116: Figure 4-48 Hi-Res Graphic Define Edit Region

    Figure 4-48 Hi-Res Graphic Define Edit Region Now, draw in the new portion of the filter curve using mouse clicks as in Step 4, above, roughly as shown below (Figure 4-49). Figure 4-49 Hi-Res Edit In Progress Complete drawing the new portion of the filter curve as shown below (Figure 4-50) by drawing points all the way to the right edge of the edit region:...

  • Page 117: Figure 4-50 Completed Hi-Res Graphic Edit

    Figure 4-50 Completed Hi-Res Graphic Edit When you have drawn the last point (must be at or beyond the right edge of the edit region), the mouse cursor will change to an "hourglass" shape for a few seconds while the filter is being recalculated.

  • Page 118: Tri Parametric Filter

    4.4.14 Tri Parametric Filter Application: The Tri Parametric Filter is a three-substage adjustable IIR filter which can be used for both peaking and nulling portions of the input signal’s frequency spectrum. Controllable parameters for each seriesed substage include Center Frequency, Width, and Boost/Cut. Typically, parametric equalizers are used as notch filters, which perform nulling of the input signal at a specified Center Frequency over a specified width.

  • Page 119: Figure 4-52 Tri Parametric Filter

    Figure 4-52 Tri Parametric Filter Description of operation: The Center Freq text box / slider controls allow the user to either type in the desired Center Frequency of each stage directly, or to make manual adjustments. Click on the left/right arrow button at either end of the slider to make fine adjustments to center frequency, or drag the scroll box to make coarse adjustments.

  • Page 120: Figure 4-53 Graphical Representation Of A Parametric Filter

    The Input Atten slider control is normally set to 0dB, but can be used to insert an attenuation of as much as 60dB in 1dB increments. This is a useful method for quickly reducing the overall gain of the four combined parametric stages without having to manually adjust all four Boost/Cut controls (for example, when a Stage Overload occurs), allowing the overall shaping characteristics of the parametric filter to be retained.

  • Page 121: Limiter/Compressor/Expander

    “quiet talker” scenarios. The three types of level processing available (three sections) in the PCAP II are limiting, compression, and expansion. Unlike an analog implementation of this process, the PCAP II digital implementation is substantially easier to set up and operate and is far more accurate.
  • Page 122 milliseconds is generally recommended for speech applications. The gain algorithm dynamically adjusts the signal amplification based on input signal level and its Gain Region (limiting, compression, or expansion). If the input signal level exceeds the Limit Threshold, it is in the Limit region. If the input signal level exceeds the Compression Threshold, but not the Limit Threshold, it is in the Compression region.

  • Page 123: Figure 4-54 Limiter/Compressor/Expander Control Window

    Figure 4-54 Limiter/Compressor/Expander Control Window Description of operation: Six different parameters are adjustable on the LCE Control Window: The Expansion Ratio can be adjusted through a range of 1:1 to 1:100 by using the scroll buttons beside its text entry box, by entering the value in its text entry box, or by clicking on the Expansion Ratio Curve using the mouse pointer and adjusting it to the desired...
  • Page 124 The Compression Ratio can be adjusted through a range of 1:1 to 100:1 by using the scroll buttons beside its text entry box, by entering the value in its text entry box, or by clicking on the Compression Ratio Curve using the mouse pointer and adjusting it to the desired value.

  • Page 125: Dsp Equalizer Control Windows

    4.5 DSP Equalizer Control Windows This section provides detailed description of the control window for each equalizer mode. For any digital Equalizer block, the control window for the selected equalizer is accessed by clicking on the Control button. The output equalizer is used to reshape the noise-reduced digitally filtered signal.

  • Page 126: Figure 4-55 20-Band Graphic Equalizer Control Window

    whenever they are needed, without having to manually adjust the slider controls. Figure 4-55 20-Band Graphic Equalizer Control Window Description of controls/indicators is as follows: Slider controls: The twenty vertical scroll bar "slider" controls are used to set the frequency response of the equalizer.
  • Page 127 when it is desired to reset all sliders from scratch. All Down 1dB This button shifts all sliders down by 1dB Button: from their current position; slider, however, will be allowed to go below -40dB. This button allows the user to shift the entire equalizer curve down so that there will be room to move one or more sliders up relative to the others.

  • Page 129: Spectral Graphic Equalizer

    PCAP II for implementation. The Edit feature allows the user to make adjustments to the equalizer shape, while the Normalize button allows the user to shift the entire equalizer curve up until the highest point is at 0dB.

  • Page 130: Dual Parametric Equalizer

    4.5.3 Dual Parametric Equalizer The Dual Parametric Equalizer is identical to the Tri-Parametric Filter described in Section 4.4.14, except that only two substages are available instead of three. Please refer to that section for operating instructions. Figure 4-56 Dual Parametric Filter...

  • Page 131: Dsp Display Selection

    4.6 DSP Display Selection 4.6.1 Spectrum Analyzer and Coefficient Display Buttons Figure 4-57 Spectrum Analyzer and Coefficient Display Buttons Pressing the Spectrum Analyzer button at any time brings up the Spectrum Analyzer window. For fast access to the Spectrum Analyzer window, press <Alt-S> on the keyboard. See Section 4.6.3 for complete instructions on operating the controls in the Spectrum Analyzer window.

  • Page 132: Display Select Window

    4.6.2 Display Select Window Clicking on View in the menu bar causes the following window (Figure 4-58) to appear: Figure 4-58 Display Select Window Click the mouse on the desired type of display. Only one display will operate at a time. The display currently active is identified in the Status box of the Master Control Panel.

  • Page 133: Spectrum Analyzer Window

    4.6.3 Spectrum Analyzer Window Application: To properly utilize the DSP Filter and Equalizer stages, it is often necessary to measure the frequency characteristics of the input signal. This assists in determining the type of filtering needed. Also, after processing the signal, it may be desirable to compare the frequency characteristics of each digital filter output to those of the input signal, thus determining the effectiveness of each digital filter.

  • Page 134: Figure 4-59 Spectrum Analyzer Window

    Figure 4-59 Spectrum Analyzer Window Description of controls/indicators is as follows: Averager Block: Controls averaging successive spectral traces. Num Averages selects the number of averages to be applied to spectral traces. The more averages applied, the smoother the displayed spectrum waveforms will be; however, the waveforms will also update more slowly as Num Averages is increased.
  • Page 135 Yellow Trace Defines what is displayed by the yellow- Block: colored spectrum trace. The Signal Select box highlights the currently selected signal and allows the user to scroll through the available signals and select a different one with a mouse click. The Gain scroll bar allows the user to apply digital gain to the Yellow Trace input signal prior to FFT analysis, allowing signals which...
  • Page 136 readout at the bottom of the display will change from blue to red. Displayed Trace: Allows the user to display the Yellow and Block: Blue spectral traces simultaneously or separately. Selecting Yellow displays the Yellow Trace only, selecting Blue displays the Blue Trace only, and selecting Both displays both the Yellow Trace and the Blue Trace.
  • Page 137 assist the user in visually judging frequency and magnitude of spectral components. A vertical red marker is used to read out the exact magnitude(s) ( Mag) of any frequency (Freq) in the spectrum display. To move the marker, simply click the mouse cursor on the desired point in the Spectrum Display area, or utilize the controls in the Marker Block, described above.

  • Page 138: Coefficient Display Window

    4.7 Coefficient Display Window Application: In setting up a 2CH Adaptive filter it is sometimes useful to display the impulse response (filter coefficients) of the filter. Additionally, it is sometimes desirable to know the precise time-domain response of any of the digital Filter stages. For these reasons, the Coefficient Display window has been provided.

  • Page 139: Figure 4-60 Coefficient Display Window

    Figure 4-60 Coefficient Display Window Description of controls is as follows: Filter Select Block: Used to select the DSP Filter stage whose coefficients are to be displayed. Available options depend upon System Bandwidth, Configuration, and Number DSP Stages settings. Coefficients to Used to select how many coefficients in the Display Block: selected Filter are to be horizontally scaled...
  • Page 140 to 512 or less, coefficients are accurately displayed; however, when Coefficients to Display is set larger than 512, the message (Max of x) will appear beside the Value indication, informing the user that only the largest value of every group of x coefficients is displayed.
  • Page 141 Coefficient Display: Coefficients are displayed in Cartesian (X,Y) format, with the Y axis representing Value in a range from -1.0 to +1.0. The X axis represents Time in seconds. A yellow grid is superimposed on the black background to assist the user in visually judging Time and Value of Filter coefficients.

  • Page 142: Master Control Pulldown Windows

    Note: Any setup files previously stored by the Digital Audio Corporation PCAP software can be loaded by both the PCAP II and MCAP software. The PCAP II software is also capable of operating the MCAP unit. Save a setup to a disk file as follows: Click on File on the Master Control menu bar.

  • Page 143: Figure 4-61 Save Setup File Window

    and type in any text desired. It is recommended that the text be descriptive of the setup's application. Figure 4-61 Save Setup File Window You will need to specify a filename for the setup. Click on the Store in File Name text box, then type the desired filename (up to 256 characters).

  • Page 144: Recalling Setups From Disk Files

    Note: Any setup files previously stored by the Digital Audio Corporation PCAP software can be loaded by both the PCAP II and MCAP software. The PCAP II software is also capable of operating the MCAP unit. Open a setup from a disk file as follows: Click on File on the Master Control menu bar.
  • Page 145 OK to open it. A message will alert the user that 60 seconds may be required to completely open the setup. An "hourglass" mouse cursor will now appear, indicating that the PCAP II is busy configuring itself with the recalled settings from disk.

  • Page 146: Viewing Dsp Displays

    4.8.3 Viewing DSP Displays Click on View to access the Display Select window shown in Figure 4-58 on page 120. See Section 4.6.2 for further details.

  • Page 147: Storing Setups To External Processor Stand-Alone Memories

    4.8.4 Storing Setups to External Processor Stand-Alone Memories Application: The PCAP II external processor has the capability to store up to ten enhancement setups internally in nonvolatile Stand- Alone memories, allowing the external processor to be operated in those setups without needing to be connected to a PC.

  • Page 148: Figure 4-63 Stand-Alone Pulldown Menu

    (Figure 4-64) will now appear: Figure 4-64 Auxiliary Switch Function Window This window allows the function of the AUX switch on the PCAP II external processor front panel to be programmed. Click on the program option desired, then click on OK.
  • Page 149 An "hourglass" cursor will now appear, indicating that t h e PCAP II is busy storing the setup in the selected Stand- Alone memory. For complete instructions on operating the PCAP II external processor from the Stand-Alone memories, please consult Section 5.0.

  • Page 150: Generating Setup Reports

    4.8.5 Generating Setup Reports The PCAP II Master Control program has a Report-Generator feature which allows hardcopy printouts of PCAP II control settings to be generated. This is useful when the enhancement procedure needs to be documented. To access this feature, click on Report- Generator in the Master Control menu bar.

  • Page 151: Figure 4-66 Help Pulldown Menu

    Click on Contents to access the WinHelp utility Contents window. The Contents window will display all the subjects for which help is available for the PCAP II Master Control program. You may browse through the displayed subjects and select help for a particular subject by double-clicking the desired subject.

  • Page 152: Operating Pcap Ii Stand-Alone

    5. OPERATING PCAP II STAND-ALONE Before the PCAP II external processor can be operated Stand-Alone, at least one of the Stand-Alone setup memories must be programmed using the procedure in Section 4.8.1. Operate the PCAP II external processor as a Stand-Alone audio processor as follows: 1.
  • Page 153 While listening with the stereo headphones, switch the MONITOR switch between INPUT and OUTPUT to hear the difference between the original and processed audio, respectively. Normally, the MONITOR LEFT and RIGHT pushbuttons are kept pushed in, but either (or both) can be pushed out at any time to listen only to either the left or right channel audio, or to mute all headphone audio.

  • Page 155: Pcap Ii Customization Options

    COM port is not COM2, it may be necessary to reconfigure the software to operate on a different COM port as follows: On the PCAP II Master Control menu bar, click on the "Settings" menu bar option. When the pulldown menu appears, click on "ComPort".
  • Page 156 If the Input Level bargraphs eventually respond to the input signal, then proper communication been achieved. Click on "File", then "Exit" to exit the PCAP II Master Control program. This will save the new COM port setting.

  • Page 157: Configuring Pcap Ii For Different Baud Rates

    6.2 Configuring PCAP II for Different Baud Rates This section is intended for advanced users, only. The PCAP II system is capable of operating at RS232 symbol rates of 9600, 14400, 19200, and 38400 baud. Each PCAP II is factory- configured to operate at 38400 baud, which works well for most PCs.

  • Page 158: Figure 6-2 Baud Rate Selection Menu

    Control program and save the new baud rate setting. Figure 6-2 Baud Rate Selection Menu 3. After storing the new baud rate by exiting the PCAP II Master Control program, test the new baud rate as follows: a. Switch on the PCAP II external processor. Make sure that the RS232 cable is properly connected between the external processor and the PC.
  • Page 159 LEDs indicate GREEN. If the Input Level bargraphs on the PCAP II Master Control screen properly respond to the input signal, then the hardware and software are correctly configured for the new baud rate.

  • Page 160: Customizing Screen Colors

    6.3 Customizing Screen Colors Many of the PCAP II Master Control program screen colors are set by the Windows environment. To change these colors, first open the Control Panel by clicking on the Start button on the Taskbar then clicking on the Settings menu option. There you will see the Control Panel icon.

  • Page 161: Pcap Ii Specifications

    Panel stereo jack and volume control. Suitable for 8 ohm stereo headsets. Monitor switches for selecting PCAP II 's inputs or outputs, as well as left / right / stereo channels. Input Level Indicators Two tricolor LEDs. Red (-6 dB),...
  • Page 162 24-bit stereo D/A converter. 64X oversampling, delta-sigma technology. Dynamic Range >90 dB. Digital Inputs / Outputs S/PDIF format RCA connectors Output rate selectable between 32kHz, 44.1kHz, and 48kHz. Digital Processing Digital Filters 4096 tap adaptive/fixed filter. Splittable into two 2048 tap filters, one 2048 tap plus two 1024, or four 1024 tap filters.
  • Page 163 Slave Microprocessor · TMS320C50 MIPS processors with program RAM and 32k x 16 data (delay) RAM. Computers Interface Standard RS232 serial interface digital filter control, coefficient transfer, and spectral analysis data. 9.6k to 38.4k baud transfer rate, adjustable. (38.4k default) Construction Packaging 1.5"...
  • Page 164 and 2.1 GB HD. Windows 95/98/NT/2000 required Color active matrix display recommended if notebook used. Signal Processing Functions Filter Configurations Mono, stereo, stereo independent Max of five DSP stages mono (four at 16 kHz BW), Max of three DSP stages stereo (two at 16 kHz BW) Adaptive Filters One-channel...

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