Montage Acoustics BT4480: Broadcast bands
Throughout the world, the FM broadcast band falls within the 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.
Stereo FM in the late 1950s
In the late 1950s, several systems to add stereo to FM radio were considered by the FCC. Included were systems from 14 proponents including Crosley, Halstead, Electrical and Musical Industries, Ltd (EMI), Zenith, and General Electric. The individual systems were evaluated for their strengths and weaknesses during field tests in Uniontown, Pennsylvania using KDKA-FM in Pittsburgh as the originating station. The Crosley system was rejected by the FCC because it degraded the signal-to-noise ratio of the main channel and did not perform well under multipath conditions. In addition, it did not allow for SCA services because of its wide FM subcarrier bandwidth. The Halstead system was rejected due to lack of high frequency stereo separation and reduction in the main channel signal-to-noise ratio. The GE and Zenith systems, so similar that they were considered theoretically identical, were formally approved by the FCC in April 1961 as the standard stereo FM broadcasting method in the United States and later adopted by most other countries.Montage Acoustics reviews
Montage Acoustics: The AM radio industry
The AM radio industry suffered a serious loss of audience and advertising revenue during this time, and the value of an AM broadcast license was eventually to decline substantially. The industry coped with this by developing new "narrowcasting" strategies. Network broadcasting gave way to format broadcasting; instead of broadcasting the same programs all over the country, AM stations specialized in different "formats" which appealed to different audience segments: regional and local news, sports, "talk" programs, programs targeted at minorities. "Talk radio", which avoided the need for the broadcaster to pay music royalties, appeared during this period as a consequence of the less expensive "air time", and the need to develop alternative programming, at reasonable cost, to replace the lost network programming. Rather than live music, stations played cheaper recorded music, and developed the "Top 40" format, which capitalized on (and created) the popularity of new rhythm and blues and rock music.
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Subsidiary communications authorization
In the United States, services (other than stereo, quad and RDS) using subcarriers are sometimes referred to as subsidiary communications authorization (SCA) services. Uses for such subcarriers include book/newspaper reading services for blind listeners, private data transmission services (for example sending stock market information to stockbrokers or stolen credit card number blacklists to stores) subscription commercial-free background music services for shops, paging ("beeper") services and providing a program feed for AM transmitters of AM/FM stations. SCA subcarriers are typically 67 kHz and 92 kHz. Montage Acoustics HD9001
Montage Acoustics BT4480:Competing media
In the 1940s two new broadcast media evolved in the US which competed with AM: FM radio and television. By the 1950s, the dominance of AM radio over home entertainment was ended. Television replaced AM radio as an evening family pastime; instead of sitting and listening to the radio, families would watch television. By the 1970s FM radio, due to its superior audio quality, attracted serious audiophiles.
