Low-power broadcasting

Low-power broadcasting is the concept of broadcasting at very low power and low cost, to a small community area. These stations tend to serve small towns, or communities within large cities in the United States. There are close to 3,000 LPTV stations in the country and they are in all markets including New York City(5 stations) to Junction City, KS (2 stations).

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 licences. The relationship between broadcasting power and signal range is a function of many things, such as the frequency band it uses e.g, SW or FM, the topography of the country in which it operates (lots of mountains or flat), atmospheric conditions, and finally the amount of radio frequency energy it transmits. As a general rule, the more energy it transmits, the further the signal goes.

LPFM, LPAM, and LPTV are in various levels of use across the world, varying widely based on the laws and their enforcement.

United States

FM radio

In the U.S., the FCC partially re-legalized LPFM licenses, after the NAB, CPB, and 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. 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.

LPFM classes in the United States

Class L1 (LP100) is from 50 to 100 watts ERP.
Class L2 (L10) is at least 1 and up to 10 watts ERP.
Class D is 10 watts TPO or less, regardless of ERP, and are no longer issued for LPFM services (since 1978).

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 class D for international purposes, but are considered to be equal in status to translators, and subordinate to full class D stations still operating.

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, set forth in 47 CFR §15.239.

Criticisms of LPFM

Many of the proponents of the new LPFM classes have been critical of the actual service. Their complaints include:

The majority of the licenses have been issued to religious broadcasters who tend to have little locally-produced programming and syndicate broadcasts originating elsewhere. Religious broadcasters counter that few secular groups are equipped to fund the continuing operations of an LPFM station.

Of the religious broadcasters, a large number have been issued to local branches of Calvary Chapel.

In some states, the local Department of Transportation operates large networks of LPFM stations that act as Highway Advisory Radio stations—a service traditionally operated at the fringes of the AM band—restricting the number of available channels.

Due to legal requirements (the controversial Radio Broadcasting Preservation Act of 2000) that LPFM stations be separated by at least 0.6 MHz from all other stations (even though most experts claim 0.4 MHz would be sufficient), in most large metropolitan areas there are no available frequencies for LPFM stations at all.

AM radio

LPAM is generally not licensed in the U.S., but is allowed on the campus of any school, so long as the normal Part 15 rules are adhered to when measured at the edge of the campus. Most college radio stations started out this way. Stations may have freestanding radio antennas, or may use carrier current methods to ride on power lines. These signals cannot pass through transformers, however, and are prone to the electromagnetic interference of the alternating current.

The exception is Travelers' Information Stations (TIS), sometimes also called highway advisory radio (HAR). These are licensed LPAM stations set up by local transport departments to provide bulletins to motorists and other travelers regarding traffic and other delays. These are often near highways and airports, and occasionally other tourism attractions such as national parks. Only governments may have licenses for TIS/HAR stations, and music is disallowed.

Television

LPTV (-LP) is common in the U.S., Canada and most of the Americas where most stations originate their own programming. Stations that do not originate their own programming are designated as translators (-TX). LPTV stations that meet additional requirements such as Children's Television Act core programming and Emergency Alert System can qualify for a Class A (-CA) license. Unlike FM and AM, unlicensed use of TV bands is prohibited for broadcasting. The amateur television channels do allow for some very limited non-entertainment broadcasting however, with some repeaters airing NASA TV during Space Shuttle missions when they are not in local use.

United Kingdom

Temporary low-power stations are allowed at times via a Restricted Service Licence.

Since 2001 longterm LPFM licences have been available in remote areas of the country. These are currently used for many establishments including military bases, universities and hospitals with fixed boundaries.

New Zealand

In New Zealand you are allowed to broadcast licence free at 0.5 Watts EIRP in the FM guardbands from 88.1 to 88.7 (or 88.1 to 88.4 within 120 km of the Sky Tower in Auckland) and from 106.7 - 107.7 MHz under a General User Radio License (GURL) issued by Radio Spectrum Management. Broadcasters on these frequencies are required to cease operations if they interfere with other, licensed broadcasters and have no protection from interference from other licensed or unlicensed broadcasters. There exists a 25km rule: You may operate two transmitters anywhere (close together), but a third transmitter must be 25km away.

There are efforts on self-regulation of the broadcasters themselves, see the yahoo (discussion page).

External links

Part-15 Low Power AM Radio in U.S.
http://dmoz.org/News/Media/Access_to_Airwaves/Low-Power_MicroRadio/
http://www.prometheusradio.org
http://www.lpfm.ws REC Networks LPFM site
http://www.lpfmnz.com Society of LPFM Broadcasters Inc. (based in Auckland, New Zealand)
http://au.groups.yahoo.com/group/LPFM_Radio/ New Zealand LPFM open discussion group
http://www.rsm.govt.nz/licensing/gurls/gurl-lpfmbc-2.html New Zealand GURL
http://www.lpam.info Information on Low Power AM Broadcasting

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