Types Broadcast relay station

1 types

1.1 broadcast translators
1.2 boosters , distributed transmission
1.3 satellite stations
1.4 semi-satellites
1.5 national networks

types
broadcast translators

in simplest form, broadcast translator facility created receive terrestrial broadcast station over-the-air on 1 frequency , rebroadcast same or substantially identical signal on frequency. these stations used in television , radio cover areas (such valleys or rural villages) not adequately covered station s main signal. can used expand market coverage duplicating programming on 1 band another.

boosters , distributed transmission

relays broadcast within or near parent station s coverage area (a fill-in ) on same channel or frequency called booster stations in u.s. however, can tricky because possible have both stations interfering each other unless designed. radio interference can avoided using exact atomic time obtained gps satellites synchronise co-channel stations, in single-frequency network.

analog television stations cannot have same-channel boosters unless opposite (perpendicular) polarisation used, due video synchronization issues such ghosting. in u.s., no new on-channel uhf signal boosters have been authorized since july 11, 1975.

distributed transmission (dtx) use of several medium-power stations (usually digital) on same frequency cover broadcast area, rather 1 high-power station repeaters on different frequency. digital television stations technically capable of sharing channel, more difficult 8vsb modulation , invariable guard interval used in atsc standard cofdm used in european , australian dvb-t standard. distributed transmission system therefore have tight synchronisation requirements require transmitters receive signal 1 central source broadcast @ 1 gps-synchronised time. dts (or dtx) not broadcast repeaters in conventional sense cannot receive signal of 1 main terrestrial broadcast transmitter rebroadcast; introduce retransmission delay breaks precise synchronisation required, causing interference between individual transmitters.

the use of virtual channels alternative, though may cause same channel appear multiple times on receiver (once each relay station), , requires user tune manually best 1 (which changes due radio propagation conditions weather). use of boosters or dtx instead causes relay stations ideally appear single signal, requires significant broadcast engineering work , not cause destructive interference each other s signals.

satellite stations

some licensed stations simulcast station. these relay stations in name , licensed same other major station. not regulated in u.s., , allowed in canada, otherwise u.s. federal communications commission (fcc) regulates radio formats ensure diverse variety of programming.

u.s. satellite stations may request federal communications commission grant exemption requirements staffed broadcast studio maintained in city of license or (in rural states) television programming simulcast in both analogue , digital during digital television transition. these stations cover vast, sparsely populated regions (an economic hardship) or operated statewide non-commercial educational radio , television systems.

semi-satellites

a television rebroadcaster sells local or regional advertising broadcast on local transmitter, , may air limited amount of distinct programming parent station. such semi-satellites broadcast own local newscasts, or separate news segments during part of newscast. example, chex-tv-2 in oshawa, ontario airs daily late afternoon/early evening news , community programs separate parent station, chex-tv in peterborough, ontario, canada. u.s. fcc prohibits on fm translator stations, allowing on different licensed stations.

in cases, semi-satellite formerly autonomous full-service station being programmed remotely through centralcasting or broadcast automation in order avoid cost of retaining full local staff. cblft, owned-and-operated station of french language network ici radio-canada télé in toronto, de facto semi-satellite of stronger ottawa sibling cboft programming has long either been identical or differed in local news , advertising. financially weak privately owned broadcaster in small market can become de facto semi-satellite gradually curtailing local production 0 , relying on commonly owned station in larger city programming (wwti in watertown, new york relies on wsyr-tv in manner). broadcast automation allows substitution of syndicated programming or digital subchannel content broadcaster unable obtain both cities.

some defunct full-service stations (such cjss-tv in cornwall, ontario, cjoh-tv-8) have been turned full satellites , originate nothing. if programming parent station must removed or substituted due local sports blackouts, modified signal de facto of semi-satellite station.

national networks

most broadcasters outside of north america maintain national network , use several relay transmitters provide same service region or entire nation. in comparison other types of relays explained above, transmitter network created , maintained independent authority, paid using television license fees, , multiple major broadcasters use same transmitters.

in north america, similar pattern of regional network broadcasting employed statewide or province-wide educational television networks such kentucky educational television, unc-tv, vermont public television, wisconsin public television, tvontario or télé-québec; state or province establishes 1 educational station , extends multiple full-power transmitters cover entire jurisdiction no capability local programming origination. in u.s., regional network of rebroadcast sites may in turn join national public broadcasting service individual member station.