|
FM broadcasting is a VHF broadcasting technology, pioneered by Edwin Howard Armstrong, which uses frequency modulation (FM) to provide high-fidelity sound over broadcast radio. The term "FM band" describes the frequency band in a given country which is dedicated to FM broadcasting. This term is slightly misleading, as it equates a modulation method with a range of frequencies. ==Broadcast bands== (詳細はVHF part of the radio spectrum. Usually 87.5 to 108.0 MHz is used, or some portion thereof, with few exceptions: * In the former Soviet republics, and some former Eastern Bloc countries, the older 65–74 MHz band is also used. Assigned frequencies are at intervals of 30 kHz. This band, sometimes referred to as the OIRT band, is slowly being phased out in many countries. In those countries the 87.5–108.0 MHz band is referred to as the CCIR band. * In Japan, the band 76–90 MHz is used. The frequency of an FM broadcast station (more strictly its assigned nominal center frequency) is usually an exact multiple of 100 kHz. In most of South Korea, the Americas, the Philippines and the Caribbean, only odd multiples are used. In some parts of Europe, Greenland and Africa, only even multiples are used. In the UK odd or even are used. In Italy, multiples of 50 kHz are used. There are other unusual and obsolete standards in some countries, including 0.001, 0.01, 0.03, 0.074, 0.5, and 0.3 MHz. However, to minimise cross-channel interference, stations operating from the same or geographically close transmitters tend to keep to at least a 0.5 MHz frequency separation even when closer spacing is technically permitted, with closer tunings reserved for more distantly spaced transmitters as potentially interfering signals are already more attenuated and so have less effect on neighbouring frequencies. RCA stereo models use multiples of 0.2 MHz, starting at 87.50 and ending at 107.90. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「FM broadcasting」の詳細全文を読む スポンサード リンク
|