Difference between revisions of "3 Meter FM Broadcast Radio"

Latest revision as of 22:36, 29 July 2015

In the United States FM Modulated Broadcast Radio runs from VHF frequencies 88 MHz to 108 MHz. This is unofficially known as the 3-Meter band, although usage of the designation is rejected by Ham Radio operators. In other countries such as Japan the 3-Meter FM broadcast band extends lower, from 76 MHz to 108 MHz.

The United States FCC has considered expanding FM broadcast radio down to 76 Mhz. Frequencies 76–88 MHz were formerly used by NTSC Analog Television channels 5 and 6. The allocation is no longer used as the frequencies are unsuitable for the new digital television system.

The country of Brazil in South America is another country planning to expand FM broadcast radio down to 76 MHz after their own conversion to digital television is complete.

FM Broadcast Radio

In the United States FM radio stations broadcast at frequencies of 87.8–107.9 MHz, this is often rounded to 88 - 108 MHz. The allocation as of 2015 spans 20.2 MHz, with channels on every odd tenth decimal place 87.9, 88.1, 88.3, 88.5, ... with 101 channels spaced .2 MHz apart. Commercial broadcasting is licensed only between 92.1 and 107.9 MHz.

On June 27, 1945 the FCC officially allocated frequencies between 88 and 108 MHz for FM broadcast radio. On March 1, 1941 W47NV began operations in Nashville, Tennessee, becoming the first modern commercial FM radio station. It wasn't until the 1970s when FM radio listenership exceeded that of the old AM broadcast radio. Credit to the technology belongs to a man named Edwin Armstrong who demonstrated FM radio to the FCC.

Microbroadcasting

You are limited to a field strength no greater than 250 microvolts per meter at a distance of 3 meters from the transmitting antenna. This rule is written in an inconvenient way because the vast majority of people do not have access to a calibrated field strength meter. The best FM receivers will provide noise-free stereo reception down to the 5 uV/m level which would be reached at a distance of about 100 feet from a rule-obeying transmitter. In other words, the signal from a legal unlicensed FM stereo transmitter will start to fade into the background static at a distance of 100 feet and will be buried in the static by the time you get 1,000 feet away.

LPFM

The FCC launched the Low Power FM (LPFM) radio service in 2000 after grassroots pressure demanded community control of the airwaves. The service is entirely commercial-free, and licenses were only granted to nonprofit organizations. Low power FM stations can operate at a maximum power of 100 watts, which generally provides coverage within three to five miles.

Unfortunately, as the FCC was starting to license new stations, Congress put a hault to it after a lobbying campaign by corporate broadcasters, which restricted new licensing opportunities.

NPR - National Public Radio was one major opponent trying to stop LPFM.

The Communications Act of 1934 replaced the FRC with the broader Federal Communications Commission (FCC), noting that their role was to“regulate the public airwaves in the public interest,” but still offering no specific requirements for soliciting the public’s input.

The first well-known micro-broadcaster was Mbanna Kantako, who used a 1 watt transmitter to broadcast to his neighbors in a Springfield, Illinois housing project starting in 1987. Kantako used his radio station to discuss police brutality and other issues affecting his neighborhood. Kantako refused to shut down his transmitter after multiple requests by the FCC, insisting that he had a right to have a voice on the airwaves.

Some in the grassroots resorted to broadcasting without obtaining a license. The flashpoint of the grassroots radio movement was the court challenges made by Stephen Dunifer. Lower courts justified these unlicensed operations.