Error rates for biternary frequency modulation

The performance of a biternary f.m. system is investigated in the presence of additive Gaussian noise and receiver band limitation. The receiver bandpass-filter bandwidth is varied and, for each bandwidth, the frequency-deviation index that minimises the error probability is found. Comparisons with binary frequency modulation of the same data rate show that biternary frequency modulation can offer lower error rates only for receiver bandwidths less than 0.63 times the bit rate.