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单词 AM broadcasting
释义

AM broadcasting

中文百科

调幅广播

调幅广播英语:Amplitude Modulation Broadcast,常缩写为AM广播)是一种利用振幅调制技术的广播方式。

调幅是二十世纪主要的广播技术,至二十一世纪的现在仍然广泛地使用中。美国中央情报局CIA统计全世界约有16,265个调幅广播电台。

调幅广播始于1906由范信达创建的实验,直到第一次世界大战成为地方性的广播电台。在接下来的十年,调幅广播技术大幅度的成长。第一家商业调幅电台始于1920年代。

英语百科

AM broadcasting 调幅广播

AM and FM modulated signals for radio. Full-form of term AM, is Amplitude Modulation , which is a kind of modulation (coding). In a modulation, the original electrical signal generated in studio, mixed with a
Farmer listening to US government weather and crop reports using a crystal radio. Public service government time, weather, and farm broadcasts were the first radio
A family listening to an early broadcast using a crystal radio around 1920.  Crystal radios, used before the advent of powered vacuum tube radios in the 1920s, could not drive loudspeakers, so the family must share earphones.
German man listening to subscription radio receiver.  Broadcasting in Germany began 1922 as a Post Office monopoly, which provided this receiver which could only receive one station.

AM broadcasting is the process of radio broadcasting using amplitude modulation (AM). AM was the first method of impressing sound on a radio signal and is still widely used today. Commercial and public AM broadcasting is authorized in the medium wave band worldwide, and also in parts of the longwave and shortwave bands. Radio broadcasting was made possible by the invention of the amplifying vacuum tube, the Audion (triode), by Lee de Forest in 1906, which led to the development of inexpensive vacuum tube AM radio receivers and transmitters during World War I. Commercial AM broadcasting developed from amateur broadcasts around 1920, and was the only commercially important form of radio broadcasting until FM broadcasting began after World War II. This period is known as the "Golden Age of Radio". Today, AM competes with FM, as well as with various digital radio broadcasting services distributed from terrestrial and satellite transmitters. In many countries the higher levels of interference experienced with AM transmission have caused AM broadcasters to specialize in news, sports and talk radio, leaving transmission of music mainly to FM and digital broadcasters.

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更新时间:2025/6/22 17:15:22