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I want to demodulate the FM intermediate frequency (IF)signal using zero crossing detection. After several trials I was able to detect all the zero crossings. Now I need to generate the audio signal using the zero crossing data. Can any body suggest me a method to do the demodulation using zero crossings.
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Zero crossing for FM demodulation? In principle you need to memorize the vector (RE,IM) and calculate the angle difference between the memorized vector and the current vector. This is the integral of your current amplitude of the demodulated signal. BUT: you need to highpass this (differentiate), because the average would grow to infinity, when your FM source is not exactly aligned to the frequency of your local oscillator. The sampling speed depends on the bandwidth you want to have, so that the angle difference of the current vector to the memorized vector is small enough not to become confused by diffs of 180° or more. regards W.S.