If the information to be transmitted (i.e. JSTOR ( November 2017) ( Learn how and when to remove this template message).Unsourced material may be challenged and removed.įind sources: "Frequency modulation" – news Please help improve this article by adding citations to reliable sources. This section needs additional citations for verification. These methods contrast with amplitude modulation, in which the amplitude of the carrier wave varies, while the frequency and phase remain constant. For this reason, most music is broadcast over FM radio.įrequency modulation and phase modulation are the two complementary principal methods of angle modulation phase modulation is often used as an intermediate step to achieve frequency modulation. In radio transmission, an advantage of frequency modulation is that it has a larger signal-to-noise ratio and therefore rejects radio frequency interference better than an equal power amplitude modulation (AM) signal. It is also used in telemetry, radar, seismic prospecting, and monitoring newborns for seizures via EEG, two-way radio systems, sound synthesis, magnetic tape-recording systems and some video-transmission systems. įrequency modulation is widely used for FM radio broadcasting. FSK is widely used in computer modems, such as fax modems, telephone caller ID systems, garage door openers, and other low-frequency transmissions. The frequencies may represent digits, such as '0' and '1'. the difference between the frequency of the carrier and its center frequency, has a functional relation to the modulating signal amplitude.ĭigital data can be encoded and transmitted with a type of frequency modulation known as frequency-shift keying (FSK), in which the instantaneous frequency of the carrier is shifted among a set of frequencies. In analog frequency modulation, such as radio broadcasting, of an audio signal representing voice or music, the instantaneous frequency deviation, i.e. FM 24-10 Combined Radiotelegraph (W/T) Procedure : FM 24-11 Combined Operating Signals : FM 24-12 Army Extract of Combined Operating Signals : FM 24-13 Air Extract Combined Operating Signals : FM 24-14 Teletypewriter Switching and Relay Procedures : FM 24-18 Radio Communication FM 24-20: Field Wire Systems : FM 24-22 Combined Visual Signaling. The technology is used in telecommunications, radio broadcasting, signal processing, and computing. With a million-volt electric arc as a source of interference behind it, the AM receiver produced only a roar of static, while the FM receiver clearly reproduced a music program from Armstrong's experimental FM transmitter W2XMN in New Jersey.įrequency modulation ( FM) is the encoding of information in a carrier wave by varying the instantaneous frequency of the wave. FM has better noise ( RFI) rejection than AM, as shown in this dramatic New York publicity demonstration by General Electric in 1940.
0 kommentar(er)
