FM Transmitters

FM (frequency modulation) transmitters can yield a number of results, depending on their power and range. Extremely low-power transmitters can be used in very small locales, for purposes such as eavesdropping. At the high end, radio transmitters are sometimes used for propaganda and psychological warfare through broadcasting. Between these extremes are the low-power radio transmitters, capable of making every user a broadcaster, that have long been an issue of concern for the Federal Communications Commission (FCC).

Mini transmitters, which have a range of about 50 feet(15.2 m), are available commercially to serve purposes such as that of a baby monitor, but are easily adapted for eavesdropping as well. Although they are capable of operating anywhere on the FM dial, from 88 to 108 MHz, the recommended range for most of these is 88 to 95 MHz, where there is least likely to be interference. Low-power FM transmitters, with a range of 100 to 400 feet (30.5–122m), make it possible to transmit voices over a greater distance, and are applied commercially for purposes such as listening to compact discs (CDs) in a car that does not have a CD player.

Both mini and low-power FM transmitters have such limited power—less than 1 watt—that they pose no concern to communications regulators. On the other hand, high-power or professional FM transmitters that are commercially available—some with as many as 35 watts of power—theoretically have the capacity to make anyone a radio broadcaster. This could pose serious concerns with regard to interference and communication jamming, and by 1998, the availability of FM transmitters forced the FCC to at least consider the idea of legalizing low-power transmission. The concept has been under consideration for some time, but many would-be broadcasters are as likely to choose the Internet as a simpler, non-interfering environment in which to operate a radio site.

In the realm of very high-power radio stations, there are many such facilities overseas operated by the federal government for the purposes of winning over local populations. In February, 2002, a year before the administration of President George W. Bush launched Operation Iraqi Freedom, it provided assistance to the opposition Iraqi National Congress as it began transmitting from the Kurdish-dominated north of Iraq on the FM dial. The United States already broadcast on short-wave radio into Iraq, but FM is both more popular and harder to jam than short-wave or AM (ampere modulation).

█ FURTHER READING:

PERIODICALS:

Braga, Newton C. "Experimenting with Small FM Transmitters." Poptronics 2, no. 9 (September 2001): 41–46.

Gordon, Michael R. "Radio Transmitter to Oppose Hussein Wins U.S. Support." New York Times. (February 28,2002): A1.

"Low-Power FM Transmitters." Electronics Now 70, no. 8 (August 1999): 37–40.

Schneider, Howard. "A Little U.S. Pop-aganda for Arabs." Washington Post. (July 26, 2002): A24.

Schweber, Bill. "FM Transmitter/Receiver Provides 433-MHz Link." EDN 47, no. 9 (April 18, 2002): 22.

SEE ALSO

FCC (United States Federal Communications Commission)
Iraqi Freedom, Operation (2003 War Against Iraq)
National Telecommunications Information Administration, and Security for the Radio Frequency Spectrum, United States
Shoe Transmitter
Short-Wave Transmitters