Error Rates for Digital Signals Demodulated by an FM Discriminator

The calculation of the error rate resulting from the detection of binary frequency shift keyed (FSK) signals using an FM discriminator low-pass filter detector is described. An example is given using an alternating mark space sequence and the results compared with those obtained using a matched filter. The results indicate that in certain regions the FM discriminator low-pass filter detector yields error rates comparable to the matched filter detector, while in other regions the matched filter significantly out performs the discriminator. An error correction device is described, which when used in conjunction with the discriminator, reduces the error rate of the discriminator detector so that it more closely approaches the matched filter detector. Experimental results are presented to verify the theory.