Adjacent channel and cochannel interferences in CPFSK systems with nonlinear transmitters and limiter-discriminator detection

The performance of continuous-phase FSK (frequency-shift keying) systems with rectangular modulation pulse shaping and limiter-discriminator detection is analytically evaluated in the presence of transmission nonlinearities as well as adjacent channel and cochannel interference. Consideration of modulation pulses with length τ, shorter than symbol time, T, is investigated. The algorithm developed to evaluate bit-error probability shows that the choice τ/T=1, and even more so in the presence of adjacent channel interference. Moreover, for τ/T=0.5, numerical results are reported that describe system performance under different working conditions and can be used to develop design criteria