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From: email@example.com (Bob Wilson)
Subject: Re: vibration measurement circuit (vibration gurus please help)
Date: Sun, 27 Oct 2002 02:34:20 -0000
Organization: Your Organization
X-Newsreader: WinVN 0.99.9 (Released Version) (x86 32bit)
In article <6EGu9.firstname.lastname@example.org>, email@example.com
>I'd like to get a graph of the vibration level (Gs) over a frequency range
>of 10 to 5kHz
>The vibration to be measured would be continuous or slowly changing over
>Seven bands over that interval would be sufficient resolution of the
>Is it valid to do this using an Analog Devices accelerometer to feed 7
>then measure the peak amplitude of each of the 7 BP outputs?
>I was thinking of using peak detectors to hold the peak experienced in each
>band over a 300mS period then use an A2D to sample the peak in each band.
>I only have an 8051 or MicroChip PIC running at 7.3MHz to do the
>A2D manipulation and serial communication to the host at 9600 bps. 3
>different axes will be sampled over the 1 second period and the host will
>request an update at 1 /second.
>I think FFT is out due to limited processing power and limited local RAM
>storing the raw waveform.
>Is this a valid approach? Will this be useful data for verifying
>qualification vibration levels for a device to be used in the same
>The desired display on the computer screen would be 3 graphs with G(peak)
>the Y axis and frequency on the X axis.
If you know the amplitude you are vibrating it at (and with many shaker
tables, you do, since it is specifically set), and you know the
instantaneous vibration frequency (assuming sinusoidal), then there is no
point at all in attempting to measure the accelerationin Gs, since you just
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