Application of negative feedback to frequency-modulation systems
01 June 1949
A general feedback formula is developed and applied to the reduction of distortion in f.m. systems. For a transmitter, feedback will reduce distortion provided a limiter is used in the feedback path to restrict variation of output with frequency. For a receiver, a limiter is required before the discriminator to obtain constant output independent of rapid variations in the input signal. The use of inverse feedback has the advantage of reducing the required bandwidth of the i.f. amplifier without sacrificing the advantage of wideband f.m.