findFFT

findFFT returns fft amplitude and frequency vectors from input data

findFFT returns fft amplitude and frequency vectors from input data, with options to return normal fft, zeropadded fft, windowed fft, or both windowed and zeropadded to remove spectral leakage.

IN
data - vector containing information to perform fft on
'-sampFreq',## - inputs sampling frequency of ##, if ## is not supplied default is 1
'-zeropad',## - option to zeropad data to ## times original size, if ## is not supplied default is 10
'-window' - Option to apply a windowing function to data
'windowtype' - string containing which windowing function to apply to data, must follow option '-window', if not supplied default is 'hann'
OUT
amp - vector containing amplitude values (y-axis)
freq - vector containing frequency values (x-axis)

Examples:
[amp freq] = findFFT(data)
[amp freq] = findFFT(data,'-sampFreq',10)
[amp freq] = findFFT(data,'-zeropad',5)
[amp freq] = findFFT(data,'-window','hamming')
[amp freq] = findFFT(data,'-sampFreq',10,'-zeropad',5,'-window','blackman')

Use plotFFTdifs.m script to see examples of how this function works and what all the different outputs look like.

References
For an excellent introduction to FFTs, zeropadding, and windowing
<http://blinkdagger.com/category/control-systems/>

For an excellent article on windowing
<http://www.ee.iitm.ac.in/~nitin/_media/ee462/fftwindows.pdf?id=jan07%3Aee462%3Arefs&cache=cache>

Written by:
Bryant Svedin
10 May, 2010