Approximative threshold-calculation of a PLL-FM-demodulator with bandpass-limiter

The author´s method (Proc. 1988 IEEE Int. Symp. Circ. Syst., p.595-8) for easily and rapidly calculating and optimizing the FM-threshold-level of a phase-locked-loop FM demodulator is extended by including a bandpass-limiter in the preselection system, based on a new threshold-criterion for the phase-error variance. It requires only a numerical integration and a zero-search instead of solving a nonlinear differential equation in the time domain; this reduces the computation time on a CRAY vector computer for a complete threshold curve from a few thousand seconds to a few seconds in all cases of practical interest. Nevertheless, the results of both theories are in good agreement within about 1 dB as well as with experimental data within the limits of measuring accuracy