A type of electronic circuit used to demodulate satellite signals.
An electronic circuit employed within a radio receiver which precisely tunes it to a station frequency and rejects interference which might otherwise hinder this operation. The synthesiser which tunes the radio uses a small quartz crystal to generate a stable reference frequency.
In electronics, a phase-locked loop (PLL) is a closed-loop feedback control system that generates and outputs a signal in relation to the frequency and phase of an input ("reference") signal. A phase-locked loop circuit responds to both the frequency and the phase of the input signals, automatically raising or lowering the frequency of a controlled oscillator until it is matched to the reference in both frequency and phase.