Broadcast translator
From Wikipedia, the free encyclopedia
In broadcasting, a translator is an FM radio station or a TV station which acts as a full-duplex repeater. Just as a verbal translator (person) listens in one language and speaks in another, a broadcast translator receives a signal from one channel and transmits it again, usually on another channel or other frequency assignment, extending the range of the original signals into areas that cannot receive them otherwise. This is common in Australia and the Americas, especially in the United States, and in mountainous regions.
For example, in Canberra, Australia, the main television transmitter is on Black Mountain in the centre of the city. To the south is the Lanyon Valley. TV signals are not able to be received by those there because of the hills. A translator was installed on top of Tuggeranong Hill so that the signal could be received from Black Mountain and then repeated into the valley. Similarly, KQED-FM in San Francisco, California, United States transmits on 88.5 MHz with its strong main transmitter. Weaker transmitters (translators) repeat the signal on 88.1 MHz in Martinez and Benicia and on 88.3 MHz in Santa Rosa.
Contents |
[edit] Rules
| This article or section deals primarily with the United States and does not represent a worldwide view of the subject. Please improve this article or discuss the issue on the talk page. |
[edit] United States
As of August 2007, the basic FCC regulations on translators are:
- No station may be translated to another band (i.e. from AM to FM) with an exception given if the translator is to be located in a "white area" where no full power AM or FM stations exist. However, the FCC is considering a rules change to allow more AMs to own and operate FM translators.
- No translator or booster may transmit anything other than the live simulcast of its licensed parent station, except for emergency warnings (such as EAS), and 30 seconds per hour of fundraising.
- The parent station must identify all of its translators and boosters between 7 and 9 a.m., between 12:55 and 1:05 p.m., and between 4 and 6 p.m. each broadcast day; or each must be equipped with its own automated device (audio or FSK) for hourly identification.
- Maximum power is 250 watts ERP for a translator, and 20% of the parent station's power for a booster.
- A translator or booster must go off the air if the parent station's signal is lost. (This helps prevent unauthorized retransmission of other stations).
Commercial stations may not own their translators (except for boosters), or be translated outside of the parent station's area (they can only fill in where terrain blocks the signal). Thus, they operate by picking up the signal of the main station off the air with a directional antenna and sensitive receiver, and directly retransmitting the signal. They also may not transmit in the FM "reserved band" from 88 to 92 MHz, where only noncommercial stations are allowed. Noncommercial stations may broadcast in the commercial band, however. Unlike commercial stations, they can also relay programming to translators via satellite, so long as those translators are in the reserved band. All stations may use any means to feed boosters.
All U.S. translator and booster stations are low-power and have a class D license, making them secondary to other stations (including the parent). They must accept any interference from full-power (100-watt or more on FM) stations, while not causing any of their own. Boosters must not interfere with the parent station within the community of license. Licenses are automatically renewed with that of the parent station and do not require separate applications, though each may still be challenged with a petition to deny.
Unlike FM, LPTV stations may operate as either translators or originate their own programming.
[edit] Boosters
Translators which broadcast within or very near the parent station's coverage area (a "fill-in") on the same channel or frequency are called booster stations. However, this can be tricky because it is possible to have both stations interfering with each other unless they are carefully designed. Interference can also be avoided by using exact atomic time obtained from GPS satellites to perfectly synchronise co-channel stations, as in a single-frequency network (SFN).
Analog TV stations cannot have same-channel boosters unless opposite (perpendicular) polarisation is used, due to video synchronization issues such as ghosting. Digital TV stations can share a channel, however this is more difficult with the 8VSB modulation and invariable guard interval used in the ATSC standard, than with COFDM used in the worldwide DVB-T standard. In North America, AM stations do not have translators or boosters, though they are actually easier to create an SFN with.
Distributed transmission (DTx) is the use of several medium-power stations (usually digital) to cover a broadcast area, rather than one high-power and several low-power stations. Experiments have shown that this can be done even with ATSC. The use of virtual channels is another alternative, though this may cause the same channel to appear multiple times on a receiver (once for each relay station it is received from), and requires the user to tune manually to the best one (which changes due to radio propagation conditions like weather). Use of boosters or DTx instead causes all relay stations to ideally appear as a single signal, but requires significant broadcast engineering to work properly and not cause destructive interference to each other's signals.
[edit] Callsigns
Translator stations in the U.S. are given callsigns which begin with a W or K (respectively east or west of the Mississippi River, as with regular stations), followed by a channel number, and two serial letters for each channel. (The first stations on that channel are AA, AB, AC, and so on.) Television channels are always two-digit, from 02 to 83; while FM radio channels are from 200 (87.9 MHz) to 300 (107.9 MHz), one every 0.2 MHz. (Example: W42BD, K263AF.) FM booster stations are given the full callsign (always including an -FM suffix, even if there is none assigned) of the parent station, plus a serial number, such as WXYZ-FM1, WXYZ-FM2, etc. LPTV stations may also choose a regular four-letter callsign with an -LP suffix for analog or -LD for digital, generally done only if the station originates programming. Digital stations which use the first option get a -D suffix (as in W42BD-D), despite the fact the full-power digital TV stations had their -DT (originally -HD) suffixes dropped by the FCC before -D and -LD were implemented. It is unknown whether digital LPTV stations keep their analog or digital channel numbers as part of their digital callsigns.
In Canada and Mexico, all translator and booster stations (called rebroadcasters in Canadian English) are given the callsign of the parent station plus a sequential number, such as XHABC and XHABC1, XHABC2, or CFON and CFON1, CFON2, etcetera. In Canada, low-power translators and boosters have the call-sign format of CH for TV or VF for FM, followed by a four-digit sequential number from a series shared by all such stations, such as CH1234 or VF1234. For medium-power rebroadcasters, the format would be CFKW-FM-1 for the first rebroadcaster of CFKW-FM. If the parent is an AM station, the parent is simply CFKW (no suffixes for AM stations), and the FM rebroadcaster is instead CFKW-1-FM.
[edit] Controversy
Critics of the FCC's licensing procedures (such as LPFM promoters and some critics of dominionism) have charged that certain noncommercial broadcasters have seriously abused FM repeater regulations in regard to nonprofit repeater licensing, by allowing satellite-delivered programming hundreds or even thousands of miles outside the parent station's coverage area[1]. Some religious outlets – such as Calvary Chapel's KAWZ-Twin Falls, Idaho or Family Radio's KEAR-FM-Sacramento – are relayed by hundreds of FM "translator" stations across the U.S. As these parent stations are owned by non-profit organizations, they are not required to have their translators receive their signal over the air, as would be required for a commercial broadcaster – a loophole that only exists for noncommercial broadcasters; [2] this particular loophole has been used by a number of religious broadcasters to set up large satellite-based networks composed almost entirely of "distant translators" – translators outside of the market area (generally a 50-mile radius surrounding the transmitter).
Particularly "bad actors" in relation to the Great Translator Invasion are several firms linked to Calvary Chapel (including Radio Assist Ministries, Horizon Broadcasting, and (formerly) Edgewater Broadcasting and REACH Media[3]) and American Family Radio owned by the American Family Association[4]. Educational Media Foundation, owners of the K-Love contemporary Christian music radio network, have also been cited as applying for distant translators en masse. The multiple networks associated with Calvary Chapel have been a particular focus in regard to translator-based networks.[5][6] due to the extremely high volume of licenses applied for (a partial list is available at RECnet[7]) At least four separate radio stations operated by Calvary Chapel churches and relaying Calvary Satellite Network programming have been identified as "home stations" for distant translators[8] and there are many home churches in addition to the main "national" Calvary Chapel concerns applying for licenses (see RECnet link above).
An FCC licensing window for new translator applications in 2003 resulted in over 13,000 applications being filed,[9] most of them coming from religious broadcasters; this has become known to LPFM advocates as the Great Translator Invasion.[10] [11][12] In many cases, multiple applications were submitted by different companies linked to Calvary Chapel in particular for the same channel.[13][14][15]
This has led to extreme difficulties for non-translator station operators, in particular LPFM license applicants. LPFM licenses often cannot get stations on the air due to translators eliminating any available channels in an area[16] and (in the case of American Family Radio in particular) there are indications that this is a deliberate strategy by the religious broadcasters in question.[17] There are also cases where translator stations owned by "sat-casting" networks have threatened licenses of existing LPFM licensees; for instance, WVAM-LP (a station operated by Maynard High School) was threatened with losing their license in preference to an application by a Calvary Chapel-linked translator (operated by Living Proof, Inc.) due to FCC rules giving preference to translators over LPFM stations.[18][19] Other LPFM stations have been similarly threatened[20][21][22][23][24] REC Networks has filed a petition with the FCC that would, among other things, require the FCC to give higher priority to LPFM stations.[25]
Eventually, the problem with "application spam" from "religiocasting" distant translator networks became sufficiently severe that the FCC issued an emergency hold order on new translator applications[26] until the present batch can be sorted through; this came after considerable criticism from LPFM lobbyist groups such as Prometheus Radio.[27] There is at least one proposed rulemaking that would revise the procedures by which nonprofit groups may apply for translators (thus closing the "distant translator" loophole); in addition, the FCC has modified channel requirements for LPFM broadcasters to open up channel space.[28][29]
In the meantime, though, there are still areas (including major metro areas) with no available FM spectrum for LPFM due to large distant translator networks (for example, Chicago IL[30] and list of issued licenses[31] which contain several Calvary Chapel and Educational Media Foundation stations; Atlanta, GA[32] and list of issued licenses[33] which contain Way-FM (associated with K-Love and Salem Communications) and Edgewater Broadcasting stations; Dallas, TX[34] and list of issued licenses[35] which show Calvary Satellite Network and American Family Radio; even Louisville, KY [36][37] and Knoxville, TN;[38][39] both small market areas, have a complete lack of LPFM channels due to distant translator invasion by Calvary Chapel and Way-FM translators in particular).
[edit] International terminology
Outside of North America the term "translator" is rarely used. Instead such facilities can be referred to variously as "relay stations" (or relays), "transposers", "repeaters", "deflectors", "boosters", "low power transmitters" "fill-in stations" "gap fillers" "secondary (or ancillary) transmitters" "rebeamers" or "beambenders".
