Data AcQuisition And Real-Time Analysis
Scope - Spectrum - Spectrogram - Signal Generator
Software for Windows
Science with your Sound Card!

Sound Card Voltmeter Screen Image

[Daqarta Voltmeter (13K image)]

The Voltmeter (like the Sound Level Meter and Frequency Counter) can be positioned anywhere on the screen. The size of the display font changes when you resize the meter by dragging its borders. You can fill the screen for a really big readout that can be seen from across the room.

The meter is shown here using RMS mode. This computes the true Root Mean Square value of the waveform of the selected channel, over an integer number of waveform cycles if Trigger is active.

The Pk-Pk (Peak-to-Peak) option finds the largest positive and negative peaks in the waveform and reports the voltage difference between them. Pos and Neg buttons allow you to see the separate positive and negative peaks.

Voltmeter dB mode is essentially the same as RMS mode, except that the value is reported in dB form. However, if you activate dB Ref, the current dB value at the moment of activation becomes the new reference value and the display immediately shows 0 dB. You can reset the reference value at any time by toggling dB Ref off and back on again.

The Voltmeter has continuous peak hold. It always retains the maximum values for each of its modes since the last Peak Reset. When the Peak Hold (Pk Hold) button is active, the maximum value for the current mode is shown instead of the instantaneous value.

In other words, the "Hold" action is always present, and the button just allows you to see the held values. You can toggle between Peak and instantaneous at any time, with no effect on the held value. The peaks for all modes are retained separately, so changing modes allows you to see the individual peaks whenever you want.

The Places control allows selection of 0 to 5 decimal places for the reported Volts, currently set to 3. A separate setting is maintained for dB mode, since you typically want less places there.

The Voltmeter TC (Time Constant) controls a "damping" value that smooths the display response when the signal is noisy.

Note that to measure voltage, your system must first be calibrated. Auto-Calibration allows Daqarta to keep track of relative sensitivity when you change Input levels, and Full-Scale Range calibration gives an absolute voltage sensitivity for each Input line.



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