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 Time Constant

Controls: Options >> Voltmeter >> TC
Macro: VoltTC

This controls the rate at which Voltmeter values can change. If the actual data values are jumping around due to noise, they can be hard to read. The time constant (TC) controls an exponential smoothing operation on the stream of changing values, so that the display shows an average value over time.

Voltmeter TC settings may range from 0 to 31, where 0 is no smoothing at all: In that case, the display changes immediately when the voltage changes. The default setting is 5.

If the true voltage changes suddenly, the display may exhibit a lag before settling to a new average. This becomes more of a problem at large TCs, so you must select a TC that is a compromise between a jittery display on noisy data, and lagging response on true voltage changes.

The TC value can be converted to an approximate time constant (seconds) by multiplying the effective trace update interval by 2^TC. This may be useful for comparison with Response Time values of the Sound Level Meter, which are given in milliseconds.

For TC = 5 (default), 2^5 = 32. So if the update interval is 17 msec (a typical value), the effective time constant would be 32 * 17 = 544 msec.

The update interval is smallest when the Trace Update interval is set to minimum, and when Trigger is off. The actual update interval also includes time for processing and displaying data. You can obtain the actual update interval from the Sgram/PT X-axis extent, divided by 512 updates per Sgram screen.

Note: The Voltmeter display freezes in Pause mode, showing the most recent instantaneous value, not the time-constant output. You can toggle to other Voltmeter modes (RMS, dB, Pk Hold, etc) while Paused, to see their most recent values.


Macro Notes:

VoltTC=5 sets the TC to 5. VoltTC=>1 increments and VoltTC=>-1 decrements the TC.


See also Voltmeter, Voltmeter Channel, Sound Level Meter Response Time, Cursor Time Constant (TC)

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