Rapid approximative calculation and optimization of PLL-FM-demodulation threshold

There is currently no analytic technique available to calculate the threshold-level for a PLL-FM-demodulator with IF-prefilter and a modulated carrier. A method is developed with a novel threshold criterion taken from the results of time-domain simulations, which allows an easy and rapid calculation of the threshold level and the optimization of the loop design with an approximation theory with accuracy of about 1 dB. However, a numerical integration must be carried out. The calculation of the whole threshold curve requires in all cases of practical interest only a few seconds on a CDC-180-990 computer. The results are in good agreement with time-domain simulations and with measurements as well, within the limits of measurement