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A phase frequency detector (PFD) is an asynchronous circuit originally made of four flip-flops (i.e., the phase-frequency detectors found in both the RCA CD4046 and the motorola MC4344 ICs introduced in the 1970s). The logic determines which of the two signals has a zero-crossing earlier or more often.
The Foster–Seeley discriminator [1] [2] is a common type of FM detector circuit, invented in 1936 by Dudley E. Foster [3] and Stuart William Seeley. The Foster–Seeley discriminator was envisioned for automatic frequency control of receivers, but also found application in demodulating an FM signal.
An envelope detector (sometimes called a peak detector) is an electronic circuit that takes a (relatively) high-frequency signal as input and outputs the envelope of the original signal. Diode detector
In radio, a detector is a device or circuit that extracts information from a modulated radio frequency current or voltage. The term dates from the first three decades of radio (1888–1918). The term dates from the first three decades of radio (1888–1918).
A Costas loop is a phase-locked loop (PLL) based circuit which is used for carrier frequency recovery from suppressed-carrier modulation signals (e.g. double-sideband suppressed carrier signals) and phase modulation signals (e.g. BPSK, QPSK).
A direct-conversion receiver (DCR), also known as a homodyne, synchrodyne, zero intermediate frequency or zero-IF receiver, is a radio receiver design that demodulates the incoming radio signal using synchronous detection driven by a local oscillator whose frequency is identical to, or very close to the carrier frequency of the intended signal.
Phase-frequency detector dynamics. Phase-frequency detector (PFD) is triggered by the trailing edges of the reference (Ref) and controlled (VCO) signals. The output signal of PFD () can have only three states: 0, +, and .
Consider a classical phase detector implemented with analog multiplier and low-pass filter. Multiplier phase detector in time domain. Here (()) and (()) denote high-frequency signals, piecewise differentiable functions (), () represent waveforms of input signals, , denote phases, and () denotes the output of the filter.