When we think of radio programming, we first think of FM radio. Although FM is by far more popular than AM radio, this wasn't always the case. FM was first developed in 1933, and by the early 40s, there were about 50 FM stations. FM radio didn't really take off until the late 60s and early 70s. For this there were a couple of reasons. The first is the advent of television, which eroded audiences for both radio and the movies. Another is the advent of FM stereo in 1960. The final, and arguably deciding factor in the advent of FM radio, is Rock and Roll.
FM bred a new kind of radio station, with maverick disc jockeys (or DJs) playing an eclectic mix of songs of their choosing. These selections, however, consisted mainly of the top rock acts of the era. This didn't sound the death-knell of AM radio (since AM still exists), but it did signal the ascendancy of FM as the radio format of choice for America's youth, who were the predominant radio listeners.
When FM is broadcast, there is more bandwidth available than is necessary. Stereo usually uses the frequencies between 19 to 53 kHz, leaving the frequencies from 53 to 100 kHz for programming. SCA--a legal term that stands for "Subsidiary Communications Authorization"--uses this extra space for special programming between the frequencies of 67 and 92 kHz. This special programming can consist of anything, but it usually takes the form of readings for the blind, multicultural radio, or other things like that.
To take advantage of these broadcasts, you need a special radio receiver. Radio SCA/SCMO offers you SCA/SCMO/AM/FM subcarrier radio decoders. Our radios offer the highest quality in both sound and reception, and are offered at surprisingly low prices.
Commercial Free Radio
SCA FM Receivers