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Showing results for tags 'spectrum'.
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Submitted by ljmayes on Mon, 10/18/2010 - 16:34 I am puzzled by the implementation of the FFT in VisSim. Normally the ouput of the discrete Fourier transform is a vector of complex numbers (excepting the dc and max frequency term which are always real). The exception is the special case when the input function is odd (when all the tranformed terms are real). In VisSim the transform is unconditionally wholly real and (to my surprise) the IFFT will accept this and reconstruct the original waveform. Additionally, there is no 'reflection' in the frequency domain. The 'help' doesn't help. What is going on?
Submitted by Joe on Wed, 10/26/2011 - 18:52 Hi, How can I look at the frequency spectrum of a portion of my data, say from 15 to 60- seconds rather than the full run of 0 to 60 seconds? Thanks, Joe