48.19 The raised cosine pulse spectrum is not the only one that satisfies Nyquist criteria. The trapezoid pulse spectrum shown in Figure P8.19 also satisfies this criteria. (a) Compute the time-domain pulse corresponding to the spec trum shown in Figure P8.19. Compare the zero crossings of this pulse with those of the raised cosine pulses and the sinc pulse. (b) Suggest another pulse spectrum that satisfies Nyquist's criterion. P(f)'