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Phase-locked loop. A phase-locked loop or phase lock loop ( PLL) is a control system that generates an output signal whose phase is fixed relative to the phase of an input signal. Keeping the input and output phase in lockstep also implies keeping the input and output frequencies the same, thus a phase-locked loop can also track an input frequency.
Radio control (often abbreviated to RC) is the use of control signals transmitted by radio to remotely operate a device. Examples of simple radio control systems are garage door openers and keyless entry systems for vehicles, in which a small handheld radio transmitter unlocks or opens doors. Radio control is also used for control of model ...
Schematic of an audio-frequency voltage-controlled oscillator A voltage-controlled capacitor is one method of making an LC oscillator vary its frequency in response to a control voltage. Any reverse-biased semiconductor diode displays a measure of voltage-dependent capacitance and can be used to change the frequency of an oscillator by varying ...
Schematic of an AGC used in the analog telephone network; the feedback from output level to gain is effected via a Vactrol resistive opto-isolator.. Automatic gain control (AGC) is a closed-loop feedback regulating circuit in an amplifier or chain of amplifiers, the purpose of which is to maintain a suitable signal amplitude at its output, despite variation of the signal amplitude at the input.
In radio equipment, Automatic Frequency Control ( AFC ), also called Automatic Fine Tuning ( AFT ), is a method or circuit to automatically keep a resonant circuit tuned to the frequency of an incoming radio signal. It is primarily used in radio receivers to keep the receiver tuned to the frequency of the desired station.
v. t. e. A series RLC network (in order): a resistor, an inductor, and a capacitor. Tuned circuit of a shortwave radio transmitter. This circuit does not have a resistor like the above, but all tuned circuits have some resistance, causing them to function as an RLC circuit. An RLC circuit is an electrical circuit consisting of a resistor (R ...
A tuned radio frequency receiver (or TRF receiver) is a type of radio receiver that is composed of one or more tuned radio frequency (RF) amplifier stages followed by a detector ( demodulator) circuit to extract the audio signal and usually an audio frequency amplifier. This type of receiver was popular in the 1920s.
An electronic oscillator is an electronic circuit that produces a periodic, oscillating or alternating current (AC) signal, usually a sine wave, square wave or a triangle wave, [1] [2] [3] powered by a direct current (DC) source. Oscillators are found in many electronic devices, such as radio receivers, television sets, radio and television ...