The effects of bandlimiting on the detection of ask signals

The effects of bandlimiting on the detection of amplitude shift keying (ASK) signals disturbed by additive Gaussian noise have been analyzed using the average threshold method and the average probability density function method, A sample detector is used. For a small signal-to-noise (S/N) ratio, both methods give almost the same probability of bit error for noncoherent detection, but for a large S/N, the average probability density function method gives a smaller probability of error than does the average threshold method. For coherent detection only the average probability density function method has been used. For the same energy of the signal, the results show that the probability of bit error using a sampler detector is optimum for BT = 0.6 for the noncoherent detection and for BT = 0.7 for the coherent detection of ASK signals. For BT £ 1.0, the sampling time t = 0.5T is optimum for the coherent and noncoherent detection. For BT > 1.0, the optimum sampling time t is variable as discussed in Chapter VI.