Performance of Narrow-Band Manchester Coded FSK with Discriminator Detection

Due to the large discrepancies m the published results, the bit error rate (BER) performance of narrow-band Manchestercoded frequency-shift-keyed systems (MCFSK) with discriminator detection is reviewed and new results are presented which agree closely with measurements. It is found that a minimum BER is obtained for a peak-to-peak frequency deviation of about 1.35 times the bit rate and a receiver bandwidth of about 1.8 times the bit rate. The published results are shown to be rather optimistic. A coherent MCFSK demodulator is then shown to perform 3 dB better than discriminator detection. It is further shown that in the range of receiver bandwidths larger than the bit rate, it is sufficient to consider the intersymbol interference effects to have come only from the two bits adjacent to the bit being detected. Finally, if the phase noise components are assumed to be Gaussian distributed, the error probability formulas obtained do not predict the correct error performance.