I like to know how to measure vibration in Hz using ADXL335/similar sensor in one axis, With that sensor, after converting digital using ADC, now i have some 8-bit binary value(0-256 in decimal)... could you tell me the steps to measure vibration in Hz?

Is there any math equation? or it will too good if you post a tutorial or program to do that.

Thanks in Advance Dinesh

  • \$\begingroup\$ Do you expect there to be only a single frequency (or one very dominant frequency). This would be the case if the sensor was mounted on a reciprocating object. Or might there be lots of frequencies, as you might get if the sensor was mounted on a car engine? \$\endgroup\$ – Rocketmagnet Jan 30 '12 at 12:43

A trivial solution could be to calculate the derivative (aka the difference between two samples) to find the relative maximum points and then calculate the time between two positive peaks.

In this case I would suggest to smooth a little bit the values (compatibly with the sampling frequency and your bandwith requirements) to avoid occurring in local maxima.

Once found the frequence you could also calculate the FFT over a number of periods and it would give you more informations about the harmonics of the vibration, if more than one.

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