Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Fast Fourier Transform Amplitude Units

  1. Dec 3, 2009 #1
    Hi there,

    So I have a multi year time series of of heights in meters that I am working on. If I compute the FFT on the data and then calculate the amplitude as: abs(FFT)/N where N is the number of samples what units do I end up with for the amplitude? Is it still in meters?
    Cheers
     
  2. jcsd
  3. Dec 3, 2009 #2

    jasonRF

    User Avatar
    Science Advisor
    Gold Member

    Yes, it is still in meters. The FFT is just taking the original data, multiplying it by exponentials (which are unitless), and summing. Dividing by N does not change the units - indeed, for the zero-frequency bin you are just averaging the original data, so it has the same units.

    jason
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Fast Fourier Transform Amplitude Units
Loading...