Filter suppressing AM noise in angle modulated signals - has parallel channels leading to summation circuits each with two filters and limiter

摘要

The filter suppresses AM noise in angle-modulated signals (FM or PM), and consists of several parallel signal channels each connecting the same input to a different input of a summation circuit. Each channel contains an amplitude limiter (BP, BP'). The centre frequencies of the BP filters in different channels are staggered. The threshold of each limiter is chosen to suppress variations in the envelop of the output signal from the preceding BP filter without causing angle distortion. The summation circuit's output is coupled via a matched filter (MF) to the angle demodulator (WD).