Data AcQuisition And Real-Time AnalysisScope - Spectrum - Spectrogram - Signal Generator
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Calibrate Wave / Master Dialogs
Manual attenuator calibration is not generally recommended; you should use the Auto-Calibrate option whenever possible. However, Auto Calibration relies upon a "loopback" connecting an output to an input, and requires that the card be capable of full-duplex operation. If you have an older card that can't do that, then manual calibration may be needed.
Note that this manual calibration procedure only applies to the output attenuator step sizes; it doesn't work for inputs. Full-Scale Range calibration must be done separately.
Important: Before you begin calibration, make sure other applications that use the sound card are completely closed. Windows (at least XP and later) can secretly "borrow" some of the sound card output range for use by such applications, leading to a calibration that is only correct when they are also active. If you always run with such an application open, such as a voice synthesizer for reading the screen, you can calibrate with it as long as you turn its volume off during the calibration to avoid interfering sounds.
The two "Calibrate - Manual" buttons at the top of the Attenuator Options dialog open the Wave Cal and Master Cal dialogs. Wave and Master are independent attenuators; each must be calibrated separately to create a complete calibration file.
Upon exiting Daqarta, you will be prompted to save the new calibration file. Accept the default filename and the file will automatically be loaded on each future start. If you have only a single sound card in your system, this file will be called Daqarta0.ATN. If you have more than one sound card, it may be Daqarta1.ATN, Daqarta2.ATN, etc. (See Managing Multiple Devices for more information.)
The .ATN file is an ordinary text file, which you can view with any text editor like Notepad. Be sure to leave the second line intact, however, since that identifies the sound card that the file applies to. The information must match that shown at the top of this dialog for the card currently in use.
You may use this .ATN file on another system, as long as it uses the exact same model of sound card and thus has the same information header. (You may have to rename the file, if it is for use as a different Select Card number.)
See also Generator Attenuator Options Dialog
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