Diversity improvement of frequency-hopped CPFSK in partial-band jamming by limiter-differential detection

The error probability achieved by a differential detector with a bandpass limiter preceding the receiver is analyzed for a slow-frequency-hopped continuous-phase frequency-shift keying (CPFSK) diversity waveform transmitted over a partial-band noise jamming channel, and is compared to the system´s performance without the bandpass limiter. In principle, each bit is repeated on L different hops and, for the frequency-hopped/CPFSK system analyzed, these repetitions are combined to yield a soft decision. The main result of the work is that a diversity gain for error rate improvement in worst-case partial-band jamming is realized for the different detector preceded by a limiter, but not for the differential detector without a limiter. This result is shown by considering the error probability for L=2 in comparison with that for L=1