Adaptive decision method for restricted band digital FM

Abstract

A technique for the detection of narrowband multilevel continuous phase frequency shift keyed signals (CPFSK signals) is introduced. This technique is a noncoherent demodulation which utilizes a limiter-discriminator-integrator (LDI) followed by a nonlinear postprocessor to combat the intersymbol interference caused by a bandlimiting filter. The error rate performance is computed for this receiver and compared with that of the LDI receiver. The proposed system was simulated and the bit error rate (BER) performances of 2, 4, and 8-ary CPFSK schemes were obtained. The proposed technique provides improved BER performances for narrowband digital FM. Simulation results have verified the superiority of this method.<>