I'm looking for ideas on the best way to develop a low cost vibrations sensor. Basically I would need to measure a transient signal (due to impulse excitation e.g. controlled blast). The frequency of interest is 10 Hz to 1,000 Hz. The main aim of the sensor is to act as a rudimentary Pass/Fail indicator, so if the detected vibration has a fundamental frequency below 500Hz then an LED light might go off or the status 'Fail' is indicated (and possibly stored for later interrogation). This does not need to be highly accurate so if the peak frequency is anything below 500Hz +/- 50Hz then this triggers an alarm/LED/etc. The main aim is to perform the peak identification in the frequency domain without an FFT (keeping cost and components to a minimum). The moment of data capture can be triggered by an external signal or by the amplitude threshold due to the blast.
The sensor will be attached to a steel structure, which is excited by controlled blasts and if the fundamental frequency of the steel structure is detected to be below the 500Hz (threshold) then an alarm is triggered.
Can this be done? Using PLL or something similar? Do you think this is feasible?
I hope my post has sufficient clarity but if i have missed something please do let me know. I am looking forward to hearing your thoughts/comments/opinions on this. Appreciate your time in entertaining my query
Thanks in advance,