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FM receivers employ a special detector for FM signals and exhibit a phenomenon known as the capture effect, in which the tuner "captures" the stronger of two stations on the same frequency while rejecting the other (compare this with a similar situation on an AM receiver, where both stations can be heard simultaneously).
With the gradual clearance of other users (notably Public Services such as police, fire and ambulance) and the extension of the FM band to 108.0 MHz between 1980 and 1995, FM expanded rapidly throughout the British Isles and effectively took over from LW and MW as the delivery platform of choice for fixed and portable domestic and vehicle-based ...
A period of allowing existing FM stations to broadcast on both the original "low" and new "high" FM bands followed, which ended at midnight on January 8, 1949, at which time all low band transmissions had to end. [18] In 1978 one additional frequency reserved for educational stations, 87.9 MHz, was allocated. [19]
FM radio on the new band had to begin from the ground floor. As a commercial venture, it remained a little-used audio enthusiasts' medium until the 1960s. The more prosperous AM stations, or their owners, acquired FM licenses and often broadcast the same programming on the FM station as on the AM station ("simulcasting"). The FCC limited this ...
AM detectors cannot demodulate FM and PM signals because both have a constant amplitude. However an AM radio may detect the sound of an FM broadcast by the phenomenon of slope detection which occurs when the radio is tuned slightly above or below the nominal broadcast frequency. Frequency variation on one sloping side of the radio tuning curve ...
The functional form of the cosine term, which contains the expression of the instantaneous phase + as its argument, provides the distinction of the two types of angle modulation, frequency modulation (FM) and phase modulation (PM). [2] In FM the message signal causes a functional variation of the instantaneous frequency. These variations are ...
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Most amateur digital modes are transmitted by inserting audio into the microphone input of a radio and using an analog scheme, such as amplitude modulation (AM), frequency modulation (FM), or single-sideband modulation (SSB). Amateur teleprinting over radio (AMTOR) D-STAR (Digital Data) a high speed (128 kbit/s), data-only mode.