Data AcQuisition And Real-Time AnalysisScope - Spectrum - Spectrogram - Signal Generator
Software for Windows
Science with your Sound Card!
Contact us about
If User Units is active and the units are Pa (Pascals) with the SPL button selected, the reported value is in SPL and is labeled as such. (You can toggle the SPL button only from Y-log Spectrum mode, but that mode is not required for Voltmeter SPL operation.)
Note that this SPL value will not be as accurate or as useful as that obtained with the Sound Level Meter option, because the Voltmeter acts in the time domain and thus does not use any Weighting Curve. More importantly, it does not use any frequency response information from the microphone calibration (.CAL or .FRD) file. If the .CAL or .FRD file specifies a certain dB correction at the current signal frequency, then the Voltmeter SPL reading will be off by that amount.
Despite these shortcomings, you may still find the Voltmeter SPL reading useful in addition to the Sound Level Meter, in certain cases where you need to read a second channel at the same time, and where you can compensate for the differences.
The Voltmeter allows you to set a relative zero dB reference via the dB Ref button. When this is active, all readings are relative to the reference value instead of 1 volt or User Unit, or the SPL reference pressure. The reported value is always shown in dB, even if SPL would otherwise be shown.
VoltMode=dB or VoltMode=4 sets the Voltmeter to dB mode. See Macro Notes under Voltmeter RMS for the complete list of mode names and numbers.
Questions? Comments? Contact us!We respond to ALL inquiries, typically within 24 hrs.
Over 30 Years of Innovative Instrumentation
© Copyright 2007 - 2017 by Interstellar Research
All rights reserved