RADIO RECEIVER WITH A PHASE LOCKED LOOP FOR A DEMODULATOR

摘要

RADIO RECEIVER WITH A PHASE-LOCKED LOOP FOR A DEMODULATOR A radio receiver with a phase-locked loop demodulator is described. The phase-locked loop includes a phase comparator, a variable frequency (voltage-controlled) oscillator, and a low pass filter. The capture range and lock range of the phase-locked loop are controlled in response to the tuning of the loop. In an AM receiver with a phase-locked loop the variable frequency oscillator of the loop supplies a reference carrier for a synchronous detector which is phase-locked to a modulated carrier. A band pass filter eliminates undesired modulation of the variable frequency oscillator by an undesired received signal.