Low-power broadcasting is electronic broadcasting at very low power and low cost, to a small community area.
The terms "low-power broadcasting" and "micropower broadcasting" (more commonly "microbroadcasting") should not be used interchangeably, because the markets are not the same. The former term is more often used to describe stations who have applied for and received official licenses. The relationship between broadcasting power and signal range is a function of many things, such as the frequency band it uses e.g., shortwave or FM, the topography of the geographical area in which it operates (mountainous or flat), atmospheric conditions, and finally the amount of radio frequency energy it transmits. As a general rule, the more energy a station transmits, the further its signal goes.
LPFM, LPAM, and LPTV are in various levels of use across the world, varying widely based on the laws and their enforcement.
In the U.S., the Federal Communications Commission (FCC) partially re-legalized LPFM licenses, after the National Association of Broadcasters (NAB), Corporation for Public Broadcasting (CPB), and National Public Radio (NPR) convinced them to stop issuing the FM class D license in 1978.
The new LPFM licenses in the United States may only be issued to nonprofit educational organizations and state and local governments. (47 CFR 73.853) Also, the one and so far only "window" for applications closed in 2003, and at present, the FCC is not entertaining any new broadcast license applications, instead conducting auctions of frequencies for full power uses only.
Officially, class D is still assigned to broadcast translators, though the rules are actually much looser (up to 250 watts ERP) than for true LPFM stations, though they may not broadcast their own programming. This is due to the influence of NPR and religious broadcasting companies, which often rely on translators. Since true class D stations can bump translators, they therefore have less competition in getting or keeping their own translators on the air with new class D stations kept off the air.
New classes L1 and L2 are still considered amateur class D for international purposes, but are considered to be equal in status to translators, and subordinate to full class D stations still operating.
Broadcast Auxiliary-Low Power stations are authorized in the frequency band 76–88 MHz; however, such stations must remain 129 kilometers (80 miles) or more distant from any other Part 73 Broadcast Station or LPTV/TV Translator station on Channel 6 if using the 87.8 to 88.0 MHz segment of the band. [47 C.F.R. 74.802] Therefore, these particular stations authorize the use of FM Channel 200 (87.9 MHz). Such stations permit transmissions of live broadcast events. [47 C.F.R. 74.831] To qualify, you must own another broadcast station, or produce TV/motion picture programming (which, with the proliferation of online TV Webcasting, is not difficult). [47 C.F.R. 74.832] Power is limited to 50 milliwatts (1/20th of 1 watt). [47 C.F.R. 74.861] These stations are licensed through the FCC's Wireless Telecommunications Bureau online by accessing ULS. There are equipment requirements in the FCC's rules, but none are too daunting for the typical citizen with an average level of income and savings. Unusual antennas are not allowed; however, gain antennas (up to about 6 db/D gain) are permitted under the rules. The license fee is currently $135 for a 4–8 year term license. Such stations are NOT restricted to filing windows, so a qualified applicant could be licensed at any time. These stations are NOT protected from interference by other broadcast entities under Parts 73 or 74 of the FCC's rules, but ARE protected from interference by the Part 15 transmitters described below.
Part 15 rules are quite strict for FM, making it nearly impossible to operate a legally-unlicensed station that can be heard more than a few yards away. The rule is a signal strength of 250 µV/m at 3 meters from the antenna within the band 88 to 108 MHz, set forth in 47 C.F.R. 15.239. Radiating cable antenna systems do allow for longer, if still narrow, radiated fields and are commonly used for building broadcast systems (stadiums, dormitories, apartments, etc...) with high success. Such systems are also used for specialized audiences for hearing assistance and language translation at events. Some communities have attempted to have multiple Part 15 stations align to form a sort of neighborhood "syndication" and legally increase the outreach, but it becomes impractical in light of the new technologies that allow for information to reach a wider audience more efficiently.
Why is Low Power FM important?
As the radio marketplace consolidates, what we hear on the airwaves is increasingly homogenized. Massive media organizations are focused on attracting the broadest audiences possible, gearing programming to the demographic groups that are most appealing to advertisers. As a result, programming that reflects local community interests and niche genres has largely disappeared.
Why is Low Power FM important for musicians?
Since commercial radio is focused on programming music with mainstream appeal, music from niche formats or independent sources is not usually heard on the radio. This impacts the livelihoods of many musicians, including jazz, classical and world music artists. Musicians find it increasingly difficult to reach listeners via the airwaves, and venues, presenting organizations, orchestras and opera companies have fewer opportunities to promote their performances and broaden their audience base.
Radio also largely ignores regional musical formats. For example, Opelousas, LA is considered the birthplace of zydeco music, but until recently the community could not hear the unique sound of its local heritage on the radio. Likewise, zydeco musicians had no way to expand their audiences. In 2003, the Southern Development Foundation began broadcasting on a Low Power frequency, and the station now plays zydeco, blues, gospel and jazz, and hosts community talk shows. This has benefited both niche musicians and the community at large.
Doesn’t public radio fill the gaps?
Public and noncommercial radio has done an admirable job supporting independent and culturally diverse music, but the increasing pressure on profitability and market share has caused public radio stations to change their formats as well. In 2001, New Hampshire Public Radio dropped all of their classical and most of their jazz programming in favor of talk-oriented fare. Residents in New Hampshire were unable to listen to classical music on the radio until an LPFM station, WCNH, received its license in 2004 and became the only classical music station in the state. Public radio stations across the country are making decisions similar to New Hampshire Public Radio’s, and moving from music programming to public affairs and talk-radio formats. This has resulted in less airtime for music of all kinds.