Broadcast relay station
A broadcast relay station, relay transmitter, broadcast translator (U.S.), rebroadcaster (Canada), or repeater (two-way radio) is a broadcast transmitter which repeats or transponds the signal of another radio station or television station, usually to an area not covered by the signal of the originating station. They may serve, for example, to expand the broadcast range of a television or radio station beyond the primary signal's coverage area, or to improve service in a part of the main coverage area which receives a poor signal due to geographic constraints. They may be (but are not usually) used to create a single-frequency network.
Less commonly, a rebroadcaster may be owned by a community group rather than the owner of the primary station.
Broadcast translators 
In its simplest form, a broadcast translator is a facility created to receive a terrestrial broadcast station over-the-air on one frequency and rebroadcast the same or substantially identical signal on another frequency. These stations are used in television and radio to cover areas (such as valleys or rural villages) not adequately covered by a station's main signal.
Boosters and distributed transmission 
Relays 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 in the U.S. However, this can be tricky because it is possible to have both stations interfering with each other unless they are carefully designed. Radio interference can be avoided by using exact atomic time obtained from GPS satellites to perfectly synchronise co-channel stations, as in a single-frequency network.
Analog TV stations cannot have same-channel boosters unless opposite (perpendicular) polarisation is used, due to video synchronization issues such as ghosting. In the US, no new on-channel UHF signal boosters have been authorized since July 11, 1975.
Distributed transmission (DTx) is the use of several medium-power stations (usually digital) on the same frequency to cover a broadcast area, rather than one high-power station with any repeaters on a different frequency. Digital TV stations are technically capable of sharing 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 European and Australian DVB-T standard. A distributed transmission system would therefore have tight synchronisation requirements which require all transmitters to receive signal from one central source for broadcast at one exact GPS-synchronised time. DTS (or DTx) are not broadcast repeaters in the conventional sense as they cannot simply receive the signal of one main terrestrial broadcast transmitter for rebroadcast; to do so would introduce a retransmission delay which breaks the precise synchronisation required, causing interference between individual transmitters.
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), 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.
Satellite stations 
Some fully licensed stations simply simulcast another station. These are relay stations only in name and are generally licensed the same as any other major station. This is not regulated in the U.S., and it is also widely allowed in Canada, which otherwise the U.S. Federal Communications Commission (FCC) regulates radio formats to ensure a diverse variety of programming.
US satellite stations may request that the Federal Communications Commission (FCC) grant an exemption to requirements that a properly staffed broadcast studio be maintained in the city of license or (in rural states) that television programming be simulcast in both analogue and digital during digital television transition. These stations most often cover vast, sparsely populated regions (an economic hardship) or are operated as statewide non-commercial educational radio and television systems.
A television rebroadcaster often sells local or regional advertising for broadcast only on the local transmitter, and may also air a very limited amount of distinct programming from their parent station. Some such "semi-satellites" broadcast their own local newscasts, or separate news segments during part of the newscast. For example, CHEX-TV-2 in Oshawa, Ontario airs separate daily late afternoon-early evening news and community broadcasts from its parent station, CHEX-TV in Peterborough, Ontario, Canada. The U.S. FCC prohibits this on FM translator stations, only allowing it on different fully licensed stations.
In some cases, a semi-satellite is a formerly autonomous full-service station which is being programmed remotely through centralcasting or broadcast automation in order to avoid the cost of retaining a full local staff. CBLFT, a French language Radio-Canada owned-and-operated station in Toronto, is a de-facto semi-satellite of its stronger Ottawa sibling CBOFT as its programming has long either been identical or differed only in local news and advertising. A financially weak privately owned broadcaster in a small market can easily become a de-facto semi-satellite by gradually curtailing local production to zero and relying on a commonly owned station in a larger city for programming (WWTI in Watertown, New York relies on WSYR-TV in this manner). Broadcast automation allows substitution of any syndicated programming or digital subchannel content which the broadcaster was unable to obtain for both cities.
Some defunct full-service stations (such as CJSS-TV in Cornwall, Ontario, now CJOH-TV-8) have been turned into full satellites and originate nothing. If programming from the parent station must be removed or substituted due to local sports blackouts, the modified signal is de-facto that of a semi-satellite station.
National networks 
Most broadcasters outside of North America maintain a national network and use several relay transmitters to provide the same service to a region or entire nation. In comparison to the other types of relays explained above, the transmitter network is often created and maintained by an independent authority, often paid for using television license fees, and multiple major broadcasters use the same transmitters.
In North America, a similar pattern of regional network broadcasting is sometimes employed by state-wide or province-wide educational television networks such as Vermont Public Television or Télé-Québec; a province establishes one educational station and extends it with multiple full-power transmitters to cover the entire jurisdiction with no capability for local programming origination. In the US, a regional network of rebroadcast sites may in turn join the national Public Broadcasting Service as an individual member station.
Relay transmitters by country 
In Canada, "rebroadcaster" or "rebroadcasting transmitter" are the terms most commonly used by the Canadian Radio-television and Telecommunications Commission.
A television rebroadcaster may be permitted to sell local or regional advertising for broadcast only on the local transmitter. On rarer occasions, they may also air a very limited amount of distinct programming from their parent station. Some such "semi-satellites" broadcast their own local newscasts, or separate news segments during part of the newscast.
There is no strict rule for the call sign of a television rebroadcaster. Some transmitters have distinct call signs from the parent station (for example, CFGC in Sudbury is a rebroadcaster of CIII), while others use the call sign of the originating station followed by a number (e.g., the former CBLFT-17 in Sarnia). Officially, the latter type includes the television station's TV suffix between the call sign and the number, although in media directories this is often left out for convenience.
In the latter case, the numbers are usually applied sequentially, starting from one and denoting the chronological order in which the station's rebroadcast transmitters began operation. Some broadcasters may, at their discretion, use a system in which the number denotes the actual broadcast channel of the transmitter (e.g., CJOH-TV-47 in Pembroke). A broadcaster cannot, however, mix the two numbering systems under a single call sign – the transmitters are either all numbered sequentially or all numbered by their analogue channel position. On the rare occasion that the sequential numbering reaches 99 (e.g., TVOntario's former broadcast transmitters), rather than being numbered as 100 the next transmitter is assigned a new call sign and numbered as one. Translators which share the same frequency (such as CBLT's former repeaters CBLET, CBLHT, CBLAT-2 and CH4113, all on channel 12) are also given distinct call signs.
Digital rebroadcasters may be numbered using the television channel number of the analogue signal which they replaced; TVOntario's CICO-DT-53 (digital UHF 26, Belleville) is one example (that station was converted in 2011 solely to vacate an out-of-core analogue channel, UHF 53, and retains CICO-TV-53's former analogue UHF TV callsign numbering as one of the few surviving TVO repeaters).
Low-power rebroadcasters may also have a call sign which consists of the letters CH followed by four numbers. For example, CH2649 in Valemount is a rebroadcaster of Vancouver's CHAN. Rebroadcasters of this type are numbered strictly sequentially to the order in which they were licensed by the CRTC, and their call signs have no inherent relationship to those of the parent stations or of other rebroadcasters. Although the next number in the sequence, CH2650 in Anzac, is also a rebroadcaster of CHAN, this is simply because CH2649 and CH2650 happened to be licensed simultaneously – the following number, CH2651, is a rebroadcaster (also in Anzac) of Edmonton's CITV. A single station's rebroadcasters are not necessarily all named in the same manner. CBLT, for example, had some retransmitters which had their own call signs, some which used CBLT followed by a number and some transmitters with CH numbers.
All CBC and Radio-Canada owned-and-operated retransmitters were shut down permanently on August 1, 2012, along with most TVOntario transmitters (which often were located at Radio-Canada sites) and some Aboriginal Programming Television Network transmitters in the far North. Private commercial broadcasters continue to operate some full-power rebroadcasters as a means of obtaining "must carry" status on cable television systems.
Transmitters in small markets with one (or no) originating stations were in most cases not required to convert to digital, even if operating full-power. Transmitters on UHF 52-69 were required to vacate those channels in 2011; some (such as a CKWS-TV retransmitter in Brighton and three of the TVOntario sites) did go digital as part of a move to a lower frequency but do not provide HDTV, extra digital subchannels or any functionality beyond that of the original analogue site.
As in television, a radio rebroadcaster may have either a distinct call sign or the call sign of the originating station followed by a numeric suffix. In the case of radio, however, the numeric suffix is always sequential.
For a rebroadcaster of an FM station, the numeric suffix is appended to the FM suffix. For example, rebroadcasters of CJBC-FM in Toronto are numbered CJBC-FM-1, CJBC-FM-2, etc. Where an AM station has a rebroadcaster operating on the FM band, the numeric suffix instead falls between the four-letter call sign and the FM suffix – for example, CKSB-1-FM is an FM rebroadcaster of the AM station CKSB, while CKSB-FM-1 would be a rebroadcaster of CKSB-FM.
As a broadcaster is limited to no more than two stations on one radio band in a market, one possible means to obtain a third FM signal in-market is to use a rebroadcaster of the AM station to move that signal onto low-power FM. In Sarnia, Ontario, Blackburn Radio already owns CFGX-FM 99.9 and CHKS-FM 106.3; its third Sarnia station CHOK 1070 uses an FM repeater for in-city coverage as "Country 103.9" FM, although officially the AM signal remains the station's primary transmitter.
Low-power radio rebroadcasters may also have a call sign which consists of the letters VF followed by four numbers. Some stations licensed under the CRTC's experimental broadcasting guidelines, a special class of short-term license (similar to special temporary authority) sometimes granted to newer campus and community radio operations, may have another distinct class of call sign which consists of three letters from anywhere within Canada's ITU prefix range followed by three digits – e.g. CFU758 or VEK565. Some other stations within this license class, however, have been assigned conventional Cxxx call signs.
Occasionally, former rebroadcasters have been converted to originating stations in their own right, but have retained their former call sign instead of being reassigned a new one of their own. Such stations include CITE-FM-1 in Sherbrooke, CBF-FM-8 in Trois-Rivières and CBAF-FM-15 in Charlottetown.
The majority of full-power television stations in Mexico are operated as repeaters or semi-satellites of the major Televisa and TV Azteca stations in Mexico City; the largest of these repeater chains rebroadcasts XEW-TV programming on more than a hundred stations nationwide. The National Polytechnic Institute's Once TV and Monterey, Mexico-based Multimedios are also commonly rebroadcast nationally; individual Mexican states each operate a chain of full-power repeaters in-state to provide public educational television.
Full-power rebroadcasters are issued callsigns in the same manner as all other stations; the callsign itself does not identify the originating station. As there are four Televisa and three TV Azteca stations in Mexico City alone, ownership of an individual transmitter by one of these groups does not in and of itself identify which signal the station is rebroadcasting. Transmitters rebroadcasting México City stations into Baja California and other communities along the Pacific Ocean coast normally operate on a two-hour delay relative to the originating station.
The smallest repeaters are operated by municipal-level organisations; these bear standard callsigns and license but are registered to a local translator authority (typically «Patronato pro TV», «Comité Patronato Municipal pro TV» or «Comité Civil pro Ant. Retrans. de T.V.» followed by the name of a municipality) and licensed for small amounts of power – often operating at a hundred watts or less. The largest repeaters are full-power satellite stations operated by national networks Televisa and TV Azteca. There is no legal distinction between translators and originating stations.
United States 
- FM translators may be used for cross-band translation. This removes the restriction that prevented FM translators from retransmitting AM signals.
- 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 am, between 12:55 and 1:05 pm, and between 4 and 6 pm 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 maximum allowable ERP for the primary station's class for a booster. There is no limit on height for fill-in translators (those that exist within the primary service contour of the primary station).
- 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).
There is one loophole by which programming may differ between a main station and an FM translator: an HD Radio signal may contain digital subchannels with different programming from the main analogue channel, and a translator may operate in such a way as to broadcast programming taken from the originating station's HD2 subchannel as the translator's main analogue signal. W237DE (95.3 Harrisburg, Pennsylvania) broadcasts the programming format formerly carried by WTCY AM 1400, but it actually gets this signal from a WNNK (104.1 FM) HD2 digital subchannel for analogue rebroadcast at the WNNK tower site on 95.3's main signal. As such, it technically is still legally an FM repeater of an FM station, even though each signal would be heard as delivering unique content by users of standard analogue FM radio receivers.
Commercial stations may own their translators or boosters when that translator or booster exists within the primary service contour of the parent station (they can only fill in where terrain blocks the signal). In fact, boosters may only be owned by the primary station. Translators outside of a primary station's service contour cannot be owned by the primary station, nor can they receive any financial support from the primary station. Most translators 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. Translators in the commercial band may only be fed by a direct off-the-air signal from another FM station or translator. Non-fill-in commercial band translators may not be fed by satellite, as spelled out in FCC rule 74.1231(b). 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.
FM translator stations may use sequential numbered callsigns, consisting of K or W, followed by a three-digit number (201 through 300 corresponding to frequencies 88.1 MHz – 107.9 MHz) followed by a pair of sequentially assigned letters. The format is similar to that used by numbered TV translators, where the number refers to the permanent channel assignment.
As of October 2008 the largest terrestrial radio translator system in the US belongs to KUER-FM, the non-commercial radio outlet of the University of Utah, with 33 translator stations ranging from Idaho to New Mexico and Arizona.
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 51 (formerly 02 to 83); while FM radio channels are from 200 (87.9 MHz) to 300 (107.9 MHz), one every 0.2 MHz. (Examples: W42BD, K263AF). The presence of an X after the number in these callsigns does not indicate an experimental broadcasting license as it may in other services, as all 26 letters are included in the sequence. The highest pair of letters used, as of January 2011[update], is ZS (K13ZS-D is a translator of KTSC in Sargents, Colorado).
Numbered translator stations (a format such as "W70ZZ") are typically low-power repeaters, often 100 watts or less on FM, and 1000 or less on TV. The former "translator band", UHF TV channels 70 through 83, was originally occupied primarily by these low-powered translators. The combination of low power and high frequencies provided a very limited range for these broadcasts. This band was reallocated to cellular telephone services in the 1980s, with the handful of remaining transmitters from these channels moved to lower frequencies.
Full-power repeaters (such as WPBS-TV's identical twin transmitter WNPI-TV) are normally assigned -TV callsigns like those of any other full-power station. These "satellite stations" do not bear numbered callsigns and must operate in the same manner as other full-power broadcasters. This simulcasting is generally not regulated by the FCC, except where a station's owner seeks to be exempted from requirements such as restrictions on owning multiple full-service stations in the same market, limits on overlap in coverage area between commonly owned stations or requirements that each full-service station have a local studio and a skeleton staff capable of originating programming locally. These exemptions are normally justified on the basis of "economic hardship", where a heavily rural location unable to support a full-service originating station of its own may be able to sustain a full-power rebroadcaster. Some stations (such as KVRR in Minnesota) are actually chains of as many as four full-power transmitters, each with its own callsign and license, covering a vast but sparsely populated region.
LPTV stations may also choose a regular four-letter callsign with an -LP suffix (shared with LPFM) for analog or -LD for digital, generally done only if the station originates programming. Class A television stations get -CA and -CD instead. Digital stations which use numerals get a -D suffix (as in W42BD-D). All of these are 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. Digital LPTV stations have their digital RF channel numbers as part of their digital callsigns, which means it may be different from the virtual channel (the analog number).
Numbered broadcast translators which are moved permanently to another frequency are normally issued new callsigns to reflect the updated channel assignments. The same is not true of displaced translators using another frequency temporarily under special technical authority, For instance, K55KD could retain its callsign while displaced temporarily to channel 57 to resolve interference to MediaFLO users, while W81AA would have received new calls when channel 81 was deleted from the bandplan. On the rare occasion a station moves back to its original channel, it is given its old callsign, as they are not reused by other stations like regular callsigns can be.
Digital transition 
LPTV operations are not required to simulcast a digital signal, nor were they required to shut down analog operation in June 2009 when full-power US TV operators had to do so.
Full-power stations used to simulcast another station were, like other full-service television broadcasters, required to convert fully to digital in June 2009. The FCC defines these "TV satellite stations" as "full-power broadcast stations authorized under Part 73 of the Commission’s rules to retransmit all or part of the programming of a parent station that is typically commonly owned." As most satellite stations operate in small or sparsely populated areas that have an insufficient economic base to support full-service operations, many were granted FCC authorization on a case-by-case basis to flash-cut from analog to digital on the same channel instead of simulcasting in both formats during the digital transition.
While no current or future DTV mandates had been forced on existing LPTV stations, Congress passed legislation in 2008 funding low-power stations which went digital by the conversion date or shortly thereafter. Some low-power stations were forced to change frequency to accommodate full-power stations which moved to UHF or operated digital companion channels on UHF during the digital transition period.
By 2011, any remaining LPTV broadcasters on UHF channel 52 through 69 were forced onto lower channels; in many cases, transmitters on the original UHF 70-83 translator band were forced to relocate twice (70-83 were lost to mobile 'phones in 1983, 52-69 were lost in 2009-2011).
Many low-power broadcast translators also were directly affected by a parent station's conversion to digital television. Translators which received an analog over-the-air signal from a full-service TV station for rebroadcast needed to convert receiving equipment in much the same way that individual viewers needed to deploy digital converters. While the signal transmitted by the repeater may remain in analog format, the uplink had to be changed. In the United States, 23% of the 4000 licensed translators have received a US$1000 federal government subsidy which covers a small portion of the cost of this additional equipment. Many other translators silently went dark after the digital transition deadline or did not apply for new channels after UHF 52-69 were removed from the bandplan.
Some small translators operated by direct conversion of a parent station's signal to another frequency for rebroadcast, without any other local signal processing or demodulation. For example, W07BA, a 16-watt repeater for Syracuse, New York broadcaster WSYR-TV, was by design a very simple piece of broadcast apparatus; it merely shifted the main station's signal from channel nine to channel seven to cover a small valley in Dewitt. After digital transition, Syracuse became a UHF island and WSYR-TV's main ABC signal became a 100 kW digital broadcast on channel seventeen. Therefore there is no longer a channel nine signal in any format available to feed the tiny repeater. Translators in remote locations, where no commercial power is available, were also expected to have problems in deploying extra equipment to handle an uplink's digital conversion. While many translators continue analog broadcasts (and a minority transitioned to digital themselves), some distant rural communities expected to find all local translator signals gone as a result of originating stations' transition to digital.
Many originating stations which were marginally available over-the-air as analog signals were irretrievably lost to digital conversion in certain locations (VHF Band I signals moving to UHF often losing the most range). This often meant that the parent station was no longer receivable over-the-air at the relay site. As an interim solution to this problem, communities that are permitted to do so by state and federal laws have chosen to purchase Ku-Band (Echostar, Hughes, etc.) or C-Band satellite receivers for their translator stations: the satellite input is simply re-broadcast as their analog translator output. Retransmitting the local channels from the satellite has the same problems as if the service area residents purchased individual service themselves: signal latency, atmospheric conditions (torrential rain or snow accumulation on the LNB), satellite equipment issues, etc.
A digital-to-digital repeater or broadcast translator is possible; in North America the ATSC specifications allow such repeaters to leave the virtual channel numbering and guide (PSIP) of the originating station unchanged, so that the rebroadcaster appears to the viewer as if it were on the same channel numbers as the original station. Some full-power television stations that have lost coverage after the digital transition have applied for digital replacement translators to fill in the gaps in some of the station's lost coverage. Those "fill-in" translators use the same call letters, suffix and facility IDs as their main full-power station.
A few local translator districts (in which one municipal or county-level group had operated multiple low-power analog retransmitters fed from multiple distant stations) consolidated all programming on digital subchannels of a single DTV transmitter on a new channel. These rebroadcast stations insert PSIP virtual channel numbering and callsigns locally.
Most digital TV sets and digital video recorders include analog and digital tuners, however most DTV set-top boxes fail to display analog stations or even to include analog passthrough for RF from the TV antenna (the way a VCR does). This is an issue primarily with coupon-eligible converter boxes and caused grave concern among LPTV operators and border stations; the Community Broadcasters Association filed a lawsuit claiming it violated the All-Channel Receiver Act, the law on which the FCC based its digital mandate. However, in late 2008, 58% of approved coupon-eligible converter models were providing analog pass-through.
Under US law, full-service local broadcasters are the primary occupants of the FM radio broadcast band. All LPFM operations, as well as all translators, are considered to be secondary in importance. In theory, this leaves low-power FM stations and broadcast translators with co-equal status on the FM band. In practice, as the FM broadcast band becomes more crowded, frequencies assigned to translators become unavailable to new LPFM stations or to existing LPFM stations seeking to upgrade their facilities.
A few key distinctions often place small, local LPFM operators at a disadvantage:
- The maximum power for an LPFM station (either 10 or 100 watts, depending on class of station) is less than that of the largest FM broadcast translators (at 250 watts), limiting the reach of the LPFM signal.
- The minimum spacing required (in distance and frequency) to other stations is less strict for translators than for LPFM applicants. While the translator spacing is based on signal contour levels (and therefore takes terrain and obstacles into account), the LPFM stations have a more restrictive legally defined minimum distance requirement.
- An LPFM broadcaster is required to generate local content; if there are multiple applicants for the same frequency, those who agree to originate eight or more hours a day of local programming are favoured. Translators are not required to (and are not licensed to) originate anything locally.
- LPFM licenses are normally issued to non-commercial educational entities (such as schools or municipalities) and are subject to strict requirements largely precluding multiple stations under common ownership. The same is not true of translators. A non-commercial translator with no local content and no educational content is free to occupy space even in the non-commercial segment (below 92 MHz) of the US FM broadcast band. During the narrow FCC filing windows for new applicants, multiple applications for broadcast translators from the same or related entities can be abused to request every locally available frequency in multiple communities.
- An LPFM license or construction permit cannot lawfully be resold. The same is not true for translators. A few related entities can easily file applications for thousands of individual translator construction permits via automated means, using non-commercial status to gain exemption from any FCC filing fees, then resell these construction permits en masse or individually for thousands of dollars each – even if the corresponding transmitters have not yet been constructed.
Broadcast translators for commercial stations are normally required to receive a signal from their parent full-service FM station over-the-air and retransmit solely within the region which should be covered by the main station. (This eliminates the need for a translator except in cases where the terrain shielding is a problem.) This same restriction does not apply to non-commercial educational stations. Any non-commercial station, even one with no local or educational content to offer, can apply for an unlimited number of translators anywhere to be fed by any means (including via satellite). The end result is a network of hundreds of small local transmitters, none of which broadcast (and none of which can lawfully broadcast) programming of interest to the local community. All take increasingly scarce available spectrum which otherwise could have been employed by local LPFM stations or used for rebroadcast of local full-service stations.
Another related issue involves the use of full-power stations to carry automated or satellite-originated programming. Any new full-service station can displace an existing low-power translator or an independent LPFM station; regulations allow this on the presumption that the full-service broadcaster would be more likely to provide a local voice to the community of license. Not all full-service broadcasters live up to this expectation. In some cases (such as the displacement of existing National Public Radio repeaters by newly created religious stations in Lake Charles, Louisiana) the result has been the loss of local or educational content. While an exactly opposite outcome to that which legislative intent had anticipated, often a small non-commercial educational translator was carrying content of higher quality than a satellite-fed full-power station for which it is displaced.
Great Translator Invasion of 2003 
An FCC licensing window for new translator applications in 2003 resulted in over 13,000 applications being filed, most of them coming from religious broadcasters. Due to the extremely high volume of license applications, LPFM advocates describe this as the Great Translator Invasion.
A few broadcasters have taken advantage of FM translator regulations which allow non-commercial stations to feed distant translators from satellite-delivered programming hundreds or even thousands of miles outside the parent station's coverage area. However, it is a misconception that all translators can be fed by satellites. Only translators located on the non-commercial portion of the FM band (88.1 to 91.9 MHz) can be so-called "Satellators". All other translators must be fed off the air by direct radio reception, except in the case of so-called "fill-in" facilities that exist within the service contour of a primary station. Translators may also be used to feed other translators, so it is possible to create small chains of translators all fed from one distant station, however, this only works until the chain is broken and, if any one translator fails, the entire network beyond the failed translator goes down, too. The application window of 2003 resulted in so many applications, that the FCC was overloaded and issued an emergency hold order on new translator applications until the present batch can be sorted through; this came after considerable criticism from LPFM lobbyist groups such as Prometheus Radio. These translator applications were all on the commercial band and none of them can be used as satellators. It is unknown how the one broadcast group with the most applications planned to deliver programming to all of the translators, but affiliated churches of the parent organization own broadcasting outlets in many of the cities.
Some religious broadcasting outlets – such as Calvary Chapel's KAWZ- Twin Falls, Idaho, Educational Media Foundation or Family Radio's KEAR-FM -Sacramento – are relayed by hundreds of FM "translator" stations across the US. As these parent stations are owned by non-profit organizations and they exist on the non-commercial part of the spectrum, they are not required to have their translators receive their signal over the air, as would be required for a commercial broadcaster. This 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).
Some LPFM advocates erroneously state that the proliferation of translators has posed difficulties for non-translator station operators, in particular LPFM license applicants who claim that they cannot get stations on the air due to translators eliminating any available channels in an area. While this may be true for future LPFM applications, it is not true for any existing LPFM broadcasters or LPFM applicants. This is because the last LPFM filing window was in 2001. All translator applications from the 2003 window were required to protect the LPFM applications already pending or authorized at that time. As a result, no LPFM station was denied due to translators.
Since so-called sat-casting translators are only permitted on the non-commercial part of the spectrum, where LPFM stations do not exist, they pose no threat to the ability of existing LPFM licensees to expand their current station facilities. Non-sat-casting translators can sometimes present a problem for existing LPFM stations and the existence of a translator, theoretically, could leave LPFM stations who have been "bumped" from existing channel assignments by new full-power stations with no available frequency to which to move. The FCC has, generally, not required LPFM stations to be displaced by full power stations. In such cases, the LPFM may be subject to increased interference from the full-powered move-in, but the FCC has adopted a "Live and let live" policy that has been used to keep existing LPFM stations operating.
There is at least one proposed rulemaking that would revise the procedures by which nonprofit groups may apply for translators (thus disallowing more than a certain number of translator applications to be owned by any one entity); in addition, the FCC has modified channel requirements for LPFM broadcasters to open up channel space. REC Networks has filed a petition with the FCC that would, among other things, require the FCC to give higher priority to LPFM stations.
Satellite translator networks 
Areas with no available FM spectrum for LPFM stations due to large distant translator networks include Chicago (with several Calvary Chapel and Educational Media Foundation stations), Atlanta (with several Way-FM – associated with K-Love and Salem Communications – and Edgewater Broadcasting stations) and Dallas, Texas (with Calvary Satellite Network and American Family Radio). Even Louisville, Kentucky and Knoxville, Tennessee, both small market areas, have a complete lack of LPFM channels due to distant translator invasion by broadcasters such as Calvary Chapel and Way-FM.
The largest satellite-fed translator networks are endeavors linked to Calvary Chapel (including Radio Assist Ministry, Horizon Broadcasting, and (formerly) Edgewater Broadcasting and REACH Media) and American Family Radio owned by the American Family Association. The multiple networks associated with Calvary Chapel have been a particular focus in regard to translator-based networks. In many cases, multiple applications were submitted by different companies linked to Calvary Chapel in particular for the same channel. 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 and there are many home churches in addition to the main "national" Calvary Chapel concerns applying for licenses.
Educational Media Foundation, owners of the K-Love contemporary Christian music radio network, have also been cited as applying for distant translators en masse.
Out-of-band translators 
As of 2009[update], the FCC officially sanctioned the use of FM translators for cross-band carriage of AM signals. although some feel that this poses a threat to LPFM stations, the FCC did not authorize the use of any new FM translators for this purpose and limited cross-band translation to existing translators that had already been authorized as of May 2009. Since no new translators were authorized, there is no increased threat to LPFMs from cross-band translation services The FCC also allows translation of HD Radio digital-only channels as inputs for analog FM-only output.
Sale of permits 
Some groups have sold their translator construction permits for a large profit. Other licensees have sold their translator stations for large amounts of money – sometimes tens of thousands of dollars or more, and many times what it costs to build one.
Australia's national radio networks (Radio National, ABC NewsRadio, Triple J, ABC Classic FM and SBS Radio) each have relay transmitters which allow each service to be broadcast as widely as possible. In order to provide this, the ABC and SBS both allow community-based relay transmitters to rebroadcast radio or television in areas which would otherwise have no service. Commercial radio broadcasters normally have relay transmitters only if the local geography (such as mountainous terrain) prevents them from broadcasting to their entire market.
Since market aggregation in the early 1990s, each television broadcaster transmits its service using multiple relays in order provide the same service throughout Australia's large market areas. While each market is often divided into submarkets due to the legacy of previous commercial broadcasts (for example, Southern Cross Ten maintains two separate stations in the single Victoria market, GLV and BCV), the only difference between these submarkets in practice is limited to news services or local advertising. Except in major cities, all major television broadcasters use the same network of transmitters, which may have dozens of relay stations in each market. As a result, some areas have had trouble starting digital or HD services due to problems with certain regional transmitters.
Because most radio and television systems in Europe are national networks, the entire radio or television system in some countries can be considered a collection of relay stations, in which each broadcaster uses a transmitter network (either developed by the public broadcaster or maintained through a government-funded authority) to provide broadcast services to the entire nation.
In most parts of Asia, satellite is the preferred method of getting a signal coverage country-wide in most countries (notable exceptions include Singapore, which outright bans civilian ownership of satellite receivers, and Malaysia, which only allows civilians ownership of receivers provided by Astro). However, terrestrial-wise, the scenario is much like that of Europe- the systems are considered national networks and is made up of a collection of relay station, maintained by a government-funded authority.
See also 
- Airborne radio relay
- Amateur radio repeater
- Communications satellite
- Cellular repeater
- Microwave radio relay
- Radio repeater
- Shortwave relay station
- Transmitter station
- Television transmitter
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