Digital FFSK demodulator

摘要

A digital fast frequency shift keying (FFSK) demodulator for demodulating an FFSK signal having components at first and second frequencies f0 and f1. The FFSK signal is sampled and the samples are processed in an arrangement which includes a monostable function (50) and a digital notch filter (51) for distinguishing between the components to provide a demodulated output. The digital notch filter (51) is arranged to filter out frequencies which are multiples of the frequencies f0 and f1.