The spectrum of impulsive noise is quite different from that of an a.m. or s.s.b. radio signal, but receivers designed to discriminate against the former have only been moderately successful.A mathematical analysis of a noise blanking receiver demonstrates the critical nature of system parameters. Signals in adjacent channels can give rise to excess noise in the wanted channel. Trapezoidal blanking functions are shown to have significant advantages, and the necessity for some means of delaying the signal before blanking is demonstrated.A noise blanking receiver incorporating an ultrasonic glass delay line is described.