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!

Spectrum Averager Peak Mode

Controls: Spect Avg Dialog >> Peak
Macro: SpavgMode=Peak

This isn't really an "averager" mode at all. In this mode, the peak value is retained at each frequency, for as many frames as you have specified. Typically, you would set this value very high and terminate the operation manually by hitting the Pause button.

You can specify Continuous Peak mode by setting the frames request to 1. (A single frame wouldn't otherwise be useful.) In this mode the total frames display will continue to increase until it reaches 2147483647, after which it will show 'Cont Peak' instead of a number. Peak operation will continue until you hit Pause, or toggle Average off to abandon it.

A typical use for Peak mode is to generate a swept frequency response that appears on a single trace. You set a very slow frequency sweep to drive the system under test, and the Peak mode will record the maximum amplitude at each frequency. See Swept Frequency Response for details.

You should typically use a Flat Top spectral window function for this application, to insure accurate peak amplitude capture.

Another use is in determining how much noise a vehicle makes as it passes by at a fixed distance. You just start the "average", wait for the vehicle to pass, and then hit Pause to see the result. You don't usually need to worry about precise timing because the vehicle will be much louder than anything else at most frequencies, so the peak will only reflect that one source.

Note that you can obtain a single dB value in addition to the spectrum. You can specify a selected portion of the spectrum with the solid and dotted cursors, and use the Sigma readout mode to get the included energy between them. You can use the Spectrum Curves dialog to apply a Weighting Curve, either a standard curve such as A or ITU-R 468, or a custom curve that you define.

Alternatively, you can use the Peak Hold option of the Sound Level Meter to get a reading of the overall spectrum, with or without the same Weighting Curves.

Peak mode is also ideal for looking at explosions, animal calls, music recordings, or anything else where you might want to know about spectral peaks but the source is not well-behaved or repeatable enough to use with a normal sync.


Macro Notes:

SpavgMode=Peak or SpavgMode=2 sets Peak mode. See Macro Notes under Spectrum Averager Mode for the complete list of mode numbers and names.


See also Averager and Spectrum Averager Controls.

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