Multi-Channel Reference Canceller USER’S MANUAL Version 1.
MicroDAC 5 Multi-Channel Reference Canceller USER’S MANUAL Version 1.5 July 20, 2007 Document Number 061103JW Phone: Fax: 919 572 6767 919 572 6786 sales@dacaudio.com www.dacaudio.com Copyright © 2006-2007 by Digital Audio Corporation All rights reserved.
Table of Contents 1 Overview............................................................................................................1 1.1 Introduction.............................................................................................1 1.2 Original Factory Configuration ................................................................1 1.3 Customization with the Software Utility...................................................2 1.4 Programming Custom Settings for Standalone Use ...............
.3 Highpass Filter......................................................................................30 6.4 Automatic Gain Control.........................................................................30 7 Installation........................................................................................................33 7.1 Windows XP/2000 Installation Instructions...........................................33 7.2 Windows Vista Installation Instructions...............................................
1 Overview 1.1 Introduction MicroDAC 5 is the latest generation of DAC's most popular tactical digital adaptive filter. The MicroDAC 5 is designed to complement your tactical surveillance efforts, packaging the most commonly used filters in a powerful and easy-to-operate unit. MicroDAC 5 contains four different filters for removing common noise problems in surveillance audio. The four filters are: A Multi-Channel Adaptive filter.
stability, and automatic crash detection is enabled to allow recovery in the event that the filter does crash. The highpass filter (HPF) and automatic gain control (AGC) can be enabled or disabled using push buttons on the front panel. The factory default HPF has a cutoff of 200 Hz (meaning all frequencies below 200 Hz will be removed). The factory default AGC can add up to 10 dB of gain to the audio. 1.
2 Rear Panel Connectors The rear panel contains the following connectors: Audio input o Four ANALOG inputs o S/PDIF input o TOSLINK optical input Audio output o Two ANALOG line outputs o TOSLINK optical output External filter control connectors o External filter freeze (EXT FRZ) o External filter clear (EXT CLR) USB 2.0 connector POWER connector Figure 2-1: MicroDAC 5 Rear Panel 2.
2.2 Using Digital Input Audio for Reference Cancellation The S/PDIF and TOSLINK inputs always receive two channels of audio, LEFT channel and RIGHT channel. For reference cancellation, these two channels may contain a stereo primary signal, a mono primary and a reference signal, or only a mono primary.
3 Standalone Controls Controls on the MicroDAC 5 unit are used to configure the audio I/O and also to provide a limited set of filter controls. While the PC software provides much finer control of the filtering in the MicroDAC 5 unit, these panel controls can be used to configure the MicroDAC 5 unit when not connected to the PC. These “standalone” controls are described below. 3.1 Front Panel Figure 3-1: MicroDAC 5 Front Panel 3.1.
the VOLUME knob always controls only the headphone level; the rear-panel output level is not adjustable. 3.1.3 Input Level Controls The center section of the front panel contains INPUT LEVELS controls for the input signals. The four LEDs above each knob provide level bargraphs for each of the input signals. The red LED in each bargraph indicates that the audio is overdriving. In general, it is a good idea to make your input signals fairly loud but without overdriving.
MONO/STEREO Selection nCH Selection MONO 1CH Description Mono input, no references. MONO 2CH, Option A Mono primary, one reference on LREF. MONO 2CH, Option B Mono primary, one reference on RIGHT. MONO 3CH, Option A Mono primary, two references on LREF and RREF. MONO 3CH, Option B Mono primary, two references on RIGHT and LREF. MONO 4CH Mono primary, three references on RIGHT, LREF, and RREF. STEREO 1CH Stereo input, no references. STEREO 2CH Stereo primary, one reference on LREF.
3.1.4.5 Clear Filters Use the CLEAR button to clear the solution of all adaptive filters. 3.1.5 Lock/Unlock Unit As marked on the front panel, the BW and nCH select buttons can be used to lock the filter controls. To LOCK or UNLOCK the unit, hold these buttons down together for three seconds; the MEM/LOCK LED in the upper right corner of the front panel will turn on or off to indicate when the state has changed. The LED is on when the unit is locked and off when the unit is unlocked.
4 Specifications 4.1 4.2 4.3 Power 9-18VDC input, 2A 2.1mm “barrel” connector, positive tip Universal AC adaptor supplied Analog Audio Line Inputs (4); o Standard RCA jack o -39dBV to +6dBV input level, adjustable gain o Zin = 25kΩ, AC coupled Line Outputs (2): o Standard RCA Jack o +6dBV output level o Zout = 100Ω, AC-coupled Headphone Jack (1): o Standard 3.
4.4 Audio Output (1): o TOSLINK optical interface, constant 24-bit data resolution and 44.1kHz sample rate Control Interface (1): o USB 2.
5 MicroDAC 5 Configuration Utility Overview 5.1 Introduction The MicroDAC 5 Configuration Utility allows for complete setup and intuitive, interactive control of all the audio processing on the MicroDAC 5, via USB connection between the hardware and a Windows®-based PC. The software can be used to control the MicroDAC 5 unit in real time.
5.3 Filters Four different filters are available to place into the signal chain. These are selectable on the right-hand side of the main screen. Figure 5-2 is a sample showing only the reference canceller filter and AGC selected. With this configuration, the audio signal is only processed by these two filters; the 1CH and Highpass (HPF) filters are excluded. Figure 5-2: Stereo 2CH Filter plus AGC The same filters are applied to both left and right channels of input.
5.5 Clearing and Freezing Filters The reference canceller and 1CH filters are adaptive filters. This means that their filter coefficients are constantly changing to adapt to new signal conditions. If you want to reset the filter coefficients and have them adapt from a fresh start, then click the “Clear Filter Solution” button. This will clear ALL the adaptive filters in both channels.
Figure 5-3: Mono sub-menu In mono mode, there are six options available, three of which are shown in the following figures: 1CH: This is a single channel without any reference cancellation.
Figure 5-4: Mono 2CH with Reference on LRef Input Figure 5-5: Mono 3CH with References on Right and LRef Inputs Page 15
Figure 5-6: Mono 4CH 5.6.2 Stereo Configurations To configure the unit for a stereo signal, click the “Channels” menu and select the “Stereo” sub-menu, as shown in Figure 5-7.
Figure 5-7: Stereo sub-menu In stereo mode, there are three options available, two of which are shown in the following figures: 1CH: This places an additional 1-CH filter on both the Left and Right Inputs and provides no reference cancellation.
Figure 5-8: Stereo 2CH Figure 5-9: Stereo 3CH Page 18
5.6.3 Audio Line Out Configuration By default, the audio line outputs on the rear panel (labeled ANALOG OUTPUTS and DIGITAL OUTPUT) always contain output audio. This default behavior allows the user to toggle between input and output on the headphones without affecting the line output. However, it may at times be desirable to have the line outputs toggle along with the headphones. To make this possible, a “Toggle Line Out with Headphones” option is available in the Channels menu, as shown in Figure 5-10.
always load to an adapting state. (If you want to clear a filter and leave it cleared for a period of time, you can first freeze adaptation and then clear the filter.) To store a configuration, click the “File” menu and then “Save Config As…”. 5.8 Recalling Configurations With the MicroDAC 5 software you can recall configurations that you have previously saved to files.
are stored in nonvolatile memory on an unknown unit.) If “No” is selected, then the most recent software configuration will be “pushed” down to the hardware, and the hardware will begin running at the settings that were in the software prior to connection. Note that “pushing” software settings will not overwrite the nonvolatile memory – if you were to disconnect, the unit would return to its stored settings unless you explicitly re-program its nonvolatile memory.
5.10.1 Locked Standalone Behavior after PC Programming After PC programming, the unit will power up in the locked state. As long as the unit is never manually unlocked, it will power up in the locked state each time power is cycled, and it will always run at the programmed settings. Note that the INPUT LEVELS controls, INPUT SELECT, and headphone controls are NOT programmed, and their controls remain fully functional even when the unit is locked. 5.10.
they are “out.” Taking one of these filters out and then putting it back in does not overwrite the programmed cutoff (for the HPF) or maximum gain (for the AGC) settings. The two adaptive filters always use their programmed enable/disable setting. There is no way to enable or disable these filters in standalone mode, so if you program the unit with one or both of these filters disabled, then it can never be enabled again until the unit is re-connected to the PC.
MONO/STEREO setting BW setting nCH setting HPF in/out AGC in/out LOCK/UNLOCK state Other settings cannot be overwritten in nonvolatile memory unless the unit is connected to the PC and explicitly reprogrammed. 5.11 Synchronizing to the MicroDAC 5 Whenever the software connects to a MicroDAC 5 hardware unit, synchronization MUST occur to maintain consistency between what is displayed in the interface and what is currently running on the unit.
6 Filters To configure a specific filter, click on that filter in the signal flow diagram on the main window. Doing so will open the configuration window for that filter. Note that, in stereo configurations, the selected settings are always applied to both channels; you cannot choose different filter settings for the left and right channels. 6.
Figure 6-1: nCH Filter Dialog Description of the controls pictured in Figure 6-1 follows: Filter Size Used to set the number of FIR filter taps in the adaptive filter. Filter size is indicated both in taps (filter order) and in milliseconds. Minimum filter size is 16 taps, but can be set as high as 4500 taps depending on the channel configuration and system bandwidth. Adapt Rate Used to set the rate at which the adaptive filter adapts to changing signal conditions (mathematically known as Mu).
samples and in milliseconds. Minimum Delay is 1 sample, but can be set to as high as 2250 samples depending on the channel configuration. Filter Output Selects the output of the filter. The normal output, or “residue,” is the primary signal that remains after the reference has been cancelled. The prediction, or rejected output, is the part of the primary signal that is removed by the reference canceller. This setting provides a way to hear what is being cancelled from the signal.
When the MicroDAC 5 is running standalone (not connected to the PC), the filter runs at whatever settings are stored in the nonvolatile memory. When running connected to the PC, finer control is available. Figure 6-2 shows the filter controls available for the 1CH adaptive filter. Figure 6-2: 1CH Filter Dialog Description of the controls pictured in Figure 6-2 follows: Filter Size Used to set the number of FIR filter taps in the adaptive filter.
Slower adapt rates take longer to reach a solution or to adapt to changing signal characteristics, but a slow rate is still quite effective for stable tones and reverberations and slow adapt rates make filter crashes less likely. Faster adapt rates may be required for changing noises, but a fast adapt rate can also affect the quality of the target speech as the filter may attack sustained vowel sounds. Prediction Span Sets the number of samples in the prediction span delay line.
changes suddenly, requiring a new filter solution; this may occur when the microphone is moved, or when processing tape recorded conversations that occurred at different locations. 6.3 Highpass Filter The Highpass filter is used to attenuate all signal frequencies below a specified cutoff frequency. This filter is used to reduce low-frequency noises, such as tape or acoustic room rumble, from the input audio. The Highpass filter is sometimes called a "rumble filter.
Figure 6-4: Automatic Gain Control Dialog The only adjustable setting available for the Automatic Gain Control is the maximum possible gain to be applied. In the example above, the maximum gain is set to 10 dB. If the output signal falls more than 10 dB below the reference level, then a 10 dB gain will be applied but the output level will still be below the reference level. The AGC is useful in near party/far party conversations where one party’s voice is much softer than the other.
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7 Installation To install the MicroDAC 5 software, insert the MicroDAC 5 Installation CD into your CD-ROM drive. If the installation software does not automatically run after several seconds you will need to manually start the installation as follows: With the MicroDAC 5 Installation CD in your CD-ROM drive click on the Start menu and then the Run option. In the window that appears type: X:\setup.exe where “X” is the drive letter of your CD-ROM. Then click OK or press Enter to start the installation. 7.
2. If .NET 2.0 is not already installed on your machine, it will be installed automatically. NOTE: The .NET 2.0 Framework is large and takes about 10 minutes to install. During this time the installation may appear to hang, or “freeze” on your system. This is normal. Do not attempt to stop the installation; just let it work and do not reboot the system. Figure 7-2: Installing Microsoft .NET 2.
3. After the .NET install completes, you will get a “Welcome” screen. If there is a MicroDAC 5 unit connected to your computer, make sure it is turned off. Then click “Next” to continue. Figure 7-3: Welcome screen 4. Setup will then install the necessary MicroDAC 5 files and drivers.
5. When Setup has completed the installation, the “Finish” screen will be displayed. Click “Finish” to close the window. Figure 7-5: Finish screen 6. After clicking Finish, you may be presented with a warning window regarding Windows XP compatibility. Click “Continue Anyway” each time this window appears. Figure 7-6: Windows driver compatibility warning.
7. Next, before running the MicroDAC 5 software, attach the MicroDAC 5 hardware to your computer via the included USB cable, and turn on the unit. After a few moments, the computer will begin the Found New Hardware setup. If you are running Windows XP: a. You will see a window asking if Windows should use Windows Update to search for software. Select “No, not this time”, then click “Next”. Figure 7-7: Hardware wizard welcome screen.
b. You will see a window asking if the software should be installed automatically. Select “Install the software automatically”, then click “Next”. The driver will begin to load. Figure 7-8: Starting the hardware wizard. c. You may again see the driver compatibility warning(s) from step 6. Again, click “Continue Anyway”. Figure 7-9: Windows driver compatibility warning.
d. Once the driver has finished installing you will be presented with a window indicating completion of the Found New Hardware wizard. Click “Finish”. Figure 7-10: Completing the hardware wizard. e. If prompted to do so, repeat steps a-d to load any additional drivers. If you are running Windows 2000: The drivers should load automatically with no intervention from you. 8.
7.2 Windows Vista Installation Instructions 1. After inserting the installation disk, you may be presented with an AutoPlay window prompting you do choose what should be done with the disk you just inserted. Choose “Run setup.exe”. Figure 7-11: AutoPlay prompt 2. Setup will extract the files it needs from the installation disk.
3. You will be presented with a “Welcome” screen. If there is a MicroDAC 5 unit connected to your computer, make sure it is turned off. Then click “Next” to continue. Figure 7-13: Welcome screen 4. You may see a Windows Vista security warning similar to that shown below. Choose “Allow” to continue installation.
5. Setup will then install the necessary MicroDAC 5 files and drivers. Figure 7-15: Installing files 6. When Setup as completed the installation, the “Finish” screen will be displayed. Click “Finish” to close the window.
7. You may see another “unidentified program” warning window; again, choose “Allow”. Figure 7-17: Windows Vista "unidentified program" warning 8. You may see a security warning about a driver with an unverifiable publisher. Choose “Install this driver anyway”.
9. Next, before running the MicroDAC 5 software, attach the MicroDAC 5 hardware to your computer via the included USB cable, and turn on the unit. After a few moments, the computer will begin installing the required drivers. This will happen automatically, with notification balloons indicating the status. Figure 7-19: Installing drivers Figure 7-20: Driver installation complete 10.
