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High Frequency that can cause g-sensor damage

  1. Jul 19, 2015 #1
    Hello All,

    Anyone can help, but first allow me to give you some background, I have a project this project is to measure the frequency of the PCB depaneling machine that might damage the sensetive component which is the gyro-sensor. The sensor will damage if the frequency is above 75kHz or 100 g (gravitational force). So, Inorder to measure this I have to use a Laser doppler vibrometer, however, the equipment that I used is not capable to measure the entire lenght of the PCB, what I did is connect the equipment to oscilloscope so that I can measure the entire lenght of the PCB. Now, I have the reading of frequency and amplitude. My question is how to convert the amplitude into acceleration/velocity to get the unit measurement of g.

    Thanks in advance!
     
  2. jcsd
  3. Jul 20, 2015 #2
    Somewhere there is likely a Fourier transform of time series data. One can perform a Fourier transform carefully and yield a spectrum that has expected units that are properly normalized in terms of amplitude (g's or m/s/s vs. frequency). Do you have the original acceleration vs. time data in known units?
     
  4. Jul 20, 2015 #3

    rcgldr

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    Can you assume a sample corresponds to a sin wave: position = amplitude x sin(time x frequency x 2 x pi)? If so, then you could use the second derivative = - amplitude x (frequency x 2 x pi)^2 x sin(time x frequency x 2 x pi). Peak acceleration would occur when sin() == 1.
     
  5. Jul 20, 2015 #4

    I have a reading of the following:
    Frequency : 171.4 Khz
    Peak-Peak : 3.28 V
    Amplitude : 120mV
    RMS : 479mV

    Base on the above data I tried to transform to Fourrier Spectrum Analyzer, However, the problem is the unit measurement of amplitude.
     
  6. Jul 21, 2015 #5

    rcgldr

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    To determine acceleration (g-force), you need amplitude ((peak to peak) / 2) as a measure of distance (not voltage).
     
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