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The same effect occurs with bipolar transistors, as described by Donald [5] E. Thomas at Bell Labs in 1954: with a tank circuit connected to the collector and the modulating audio signal applied between the emitter and the base, a single-transistor FM transmitter is created. [6]
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.
Inherently, any circuit above absolute zero generates some random noise that adds to the desired signals. In some cases, atmospheric noise is far greater than that produced in the receiver's own circuits, but in some designs, measures such as cryogenic cooling are applied to some stages of the receiver, to prevent signals from being obscured by ...
The detection process described above can also be accomplished by combining, in an exclusive-OR (XOR) logic gate, the limited original FM signal and either a copy of that signal passed through a network which imposes a phase shift that varies with frequency, e.g. an LC circuit (and then limited as well), or a fixed-frequency square wave carrier ...
A radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna. Radio waves are electromagnetic waves with frequencies between about 30 Hz and 300 GHz. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating current, the ...
A personal FM transmitter is a low-power FM radio transmitter that broadcasts a signal from a portable audio device (such as an MP3 player or a smartphone) to a standard FM radio. Most of these transmitters plug into the device's headphone jack and then broadcast the signal over an FM broadcast band frequency, so that it can be picked up by any ...
A frequency synthesizer is an electronic circuit that generates a range of frequencies from a single reference frequency. Frequency synthesizers are used in devices such as radio receivers, televisions, mobile telephones, radiotelephones, walkie-talkies, CB radios, cable television converter boxes, satellite receivers, and GPS systems.
An American FM radio transmitter in Buffalo, NY at WEDG Edwin Howard Armstrong (1890–1954) was an American electrical engineer who invented wideband frequency modulation (FM) radio. [ 12 ] He patented the regenerative circuit in 1914, the superheterodyne receiver in 1918 and the super-regenerative circuit in 1922. [ 13 ]