DETECTION OF DIGITAL FSK USING A PHASE-LOCKED LOOP.

A classical problem in digital FSK modulation is the evaluation of the receiving system performance when an estimator-correlator that incorporates a phase-locked loop is employed. This paper examines the problem using a new approach which is based upon the renewal Markov process theory and the Meyr distribution. The effective noise is properly characterized by unfolding the renewal Markov process associated with the loop phase error. The assumptions inherent in the analysis apply to the case where the bandwidth of the if filter which precedes the phase-locked loop is designed to be several times the data rate because of frequency uncertainties due to channel Doppler and oscillator instabilities, but the frequency deviation to data rate ratio may be chosen small (if desired) to optimize system error probability performance. In addition to presenting results for the case where the oscillator instabilities are assumed absent and channel Doppler is perfectly tuned out at the receiver oscillator, the effects of small residual Doppler on system error probability performance is considered.