Automatic frequency control: Difference between revisions

Revision as of 12:18, 20 January 2012

Revision as of 19:08, 12 March 2012

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{{Unreferenced stub|auto=yes|date=December 2009}}

In [[radio]] equipment, '''Automatic Frequency Control''' (AFC) is a method (or device) to automatically keep a [[resonant circuit]] [[Tuner (electronics)|tuned]] to the [[frequency]] of an incoming [[radio signal]]. It is primarily used in [[radio receiver]]s to keep the receiver [[Tuner (electronics)|tuned]] to the frequency of the desired station.

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Assuming that a receiver is nearly tuned to the desired frequency, the AFC [[electrical network|circuit]] in the receiver develops an error [[voltage]] proportional to the degree to which the receiver is mistuned. This error voltage is then [[Feedback|fed back]] to the tuning circuit in such a way that the tuning error is reduced. In most [[frequency modulation]] (FM) detectors an error voltage of this type is easily available. See [[Negative feedback]].

AFC is also called Automatic Fine Tuning (AFT) in radio and TV receivers. It became rare in this application, late in the 20th century, as the more effective [[frequency synthesizer]] method became cheaper and more widespread.

== See also ==