FM Demodulator Time-Constant Requirements for Interference Rejection

Abstract

Under conditions of high-level interference fm receiver performance is often impaired because of improper low-frequency time constants in the limiter and discriminator circuits. The computation of the upper bounds on the permissible values of these time constants is illustrated. Severe restrictions are indicated which often conflict with other fundamental requirements. The computational results of this paper demonstrate that these severe restrictions can be alleviated by means of simple schemes that will greatly enhance the capture performance of the fm receiver.