Daqarta
Data AcQuisition And Real-Time Analysis
Scope - Spectrum - Spectrogram - Signal Generator
Software for Windows
Science with your Sound Card!
The following is from the Daqarta Help system:

Features:

Oscilloscope

Spectrum Analyzer

8-Channel
Signal Generator

(Absolutely FREE!)

Spectrogram

Pitch Tracker

Pitch-to-MIDI

DaqMusiq Generator
(Free Music... Forever!)

Engine Simulator

LCR Meter

Remote Operation

DC Measurements

True RMS Voltmeter

Sound Level Meter

Frequency Counter
    Period
    Event
    Spectral Event

    Temperature
    Pressure
    MHz Frequencies

Data Logger

Waveform Averager

Histogram

Post-Stimulus Time
Histogram (PSTH)

THD Meter

IMD Meter

Precision Phase Meter

Pulse Meter

Macro System

Multi-Trace Arrays

Trigger Controls

Auto-Calibration

Spectral Peak Track

Spectrum Limit Testing

Direct-to-Disk Recording

Accessibility

Applications:

Frequency response

Distortion measurement

Speech and music

Microphone calibration

Loudspeaker test

Auditory phenomena

Musical instrument tuning

Animal sound

Evoked potentials

Rotating machinery

Automotive

Product test

Contact us about
your application!

Voltmeter dB

Controls: Options >> Voltmeter >> dB
Macro: VoltMode=dB

Voltmeter dB mode is essentially the same as RMS mode, except that the value is reported in dB form. All the same Trigger considerations apply.

If the selected channel is uncalibrated, the dB value is given relative to full scale on the current range.

If the channel is calibrated, the dB value is relative to 1 volt, including Full-Scale Range and External Gain settings.

If User Units is active on a calibrated channel, the reported dB value is relative to one User Unit, so it also includes the Units/Volt factor.

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.

For bursts or other dynamic signals, there may also be differences due to the Voltmeter Time Constant versus the Response Time settings of the Sound Level Meter.

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.


Macro Notes:

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.


See also Voltmeter, Voltmeter Channel, Sound Level Meter

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