An Investigation of a Method for Obtaining a Numerical Indicator of Phase Coherence.
NAVAL POSTGRADUATE SCHOOL MONTEREY CALIF
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The Fast Fourier Transform FFT has dramatically changed the signal processing field by allowing the transformation of data from the time domain to the frequency domain at speeds rivaling and in many cases exceeding real time. The output spectrum obtained from the FFT depends on the amplitudes and the phase coherence of the sinusoids that comprise the input waveform. It is the purpose of this investigation to modify the FFT so that it will rely more heavily on the phase coherence of these sinusoids rather than on their amplitude. In this way a second indicator of signal presence or absence would be available to add more reliability to the estimation process. The study proposes a method for reducing the dependence of the output coefficients on input amplitudes and investigates its merits with several types of data. A method of displaying the phase coherence indicators is presented. Author