When you listen to your FM radio, you often get more than meets the eye. Or, to put it more accurately, ear. When FM stations broadcast, they are allotted a channel width of 200 kHz. So if the station's location on the dial is 99.1 (which is really 99.1 MHz, or 99,100 kHz), this means that the station can broadcast from the frequencies 99,000 to 99,200 kHz.
Because the human ear can only hear frequencies up to 15 kHz, this leaves a lot of bandwidth left over. Each FM radio transmission uses only a certain amount of frequency for the broadcast of stereo (usually between 19 and 53 kHz). Some radio stations use the excess bandwidth to broadcast what are called subcarrier transmissions.
These subcarrier transmissions can contain just about anything, but the most common uses are for multilingual broadcasting, reading services for the blind, or even certain types of data transmission. These types of transmission usually are called "SCA transmissions," which stands for Subsidiary Communications Authority, the name of the governing branch of the FCC. A normal FM radio (the type in your car, for instance) is not capable of decoding these transmissions. To do this, you need a special type of receiver.
The best place for you to get a subcarrier radio is through Radio SCA. We manufacture the highest-quality subcarrier radios on the market for prices that are extremely reasonable. For your convenience, you can purchase these radios directly through us using your credit card, or you can visit our store on eBay. Either way, you'll be getting a superior radio at a low price.
Commercial Free Radio
SCA FM Receivers