Optimum angle demodulation with saturation nonlinearity in the modulator

The problem of optimum demodulation of PM and FM signals when the phase modulator employed in the transmitter of the communication system exhibits saturation effects is studied. Quasi-optimum receivers with zero and finite lag are designed by making use of the state variable techniques. Performance results are presented graphically for a class of message signals, and it turns out that the effect of saturation in the phase modulator on the average performance of the system is essentially to reduce the modulation index.