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!

CPM (RPM) Spectrum

Controls: X-Axis Dialog >> CPM
Macro: CPM

This button toggles the X-axis units in Spectrum modes between Hertz and Cycles Per Minute (CPM). This is intended for use when observing machine vibrations that may correlate with revolutions per minute (RPM). You may toggle this state directly (even if the dialog is not visible) via ALT+SHIFT+C.

By default, CPM mode simply applies a factor of 60 seconds/minute to the former hertz values. That means that 2 kHz becomes 120000 CPM, shown as 120 kCPM or even 0.12 MCPM depending on the total axis range.

However, that only gives true RPM for a source that emits one cycle per revolution. If you are monitoring (say) gear noise that involves one event per tooth, the results would be too high by a factor equal to the number of teeth.

To read true shaft RPM, open the Frequency Counter (from the Options Menu, or directly via CTRL+F). Then set the Cylinders (Cyl) control at the the far right end of the Frequency Counter window to twice the number of gear teeth.


Macro Notes:

CPM=1 sets CPM mode, CPM=0 turns it off, and CPM=x toggles the current state.


See also X-Axis Control Dialog

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