Vibration Measurement Units

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lord page
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Joined: Tue Aug 24, 2010 6:45 pm

Vibration Measurement Units

Post by lord page »

Hi guys,

I am looking into buying a 4000A Series scope for vibration measurements, but I am little confused looking at the data sheet.

In FFT mode, the data sheet states that the only scales available are mv or db. Is this correct?

I need to measure mm/s, mm/s2 and displacement in FFT and raw time waveform using a 100mv/g accelerometer.

Reading through the literature from pico, the scope is being sold under the "condition monitoring" umbrella. These units are basic measurements for vibration.

Hopefully I am missing something. Can anyone confirm that it is possible to use these units/scales without using external software?

Cheers

Andrew
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Gerry
PICO STAFF
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Posts: 1053
Joined: Mon Aug 11, 2014 11:14 am

Re: Vibration Measurement Units

Post by Gerry »

Hi Andrew,

Sorry for the long delay in answering. I have been off work for different reasons, and only just caught up with a heavy workload, and backlog of Helpdesk tickets.

In Spectrum (FFT) Mode the available vertical scales are mv or the relative scale of dB depending upon which reference is used for the decibel scale. mm/s is a time domain measurement (per second), as is mm/s^2 (per second squared). If you want to measure how displacement varies with both frequency and time at the same time, then you would need either use a 3 dimensional plot or colour intensity map to display the value of the third dimension for your graph (an FFT plot is only a 2 dimensional plot, as the time over which the FFT is calculated is averaged for the entire range of values used in the FFT). Unfortunately, we do not plot 3 dimensional graphs or intensity graphs (heat maps) in our software.

Regards,

Gerry
Gerry
Technical Specialist

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