Filling transmitter
A filler transmitter is a terrestrial transmitter, usually of medium or lower transmission power, for the coverage of areas that cannot be adequately supplied by basic network transmitters or other filler transmitters. Fill transmitters are used both for the distribution of radio programs in the medium wave range and in the VHF range and for the distribution of television programs . In the long-wave range no gap-fillers are usually operated. This also applies to the shortwave range , which is only used to cover areas far away from the transmitter locations.
Both filling transmitters and basic network transmitters can be located at a transmission location, for example a filling transmitter for medium wave at the location of a VHF basic network transmitter.
Fill transmitters can receive their program - like basic network transmitters as well - via modulation lines , radio link , satellite or from a well receivable remote basic network transmitter.
Converter for analog television programs
In analog television in particular, such as PAL , many filling transmitters were operated as converters, in that they received the transmission signal from a basic network transmitter or other filling transmitter by means of ball reception and then transmitted it again after frequency conversion and amplification (see converter ). The frequency conversion is necessary to avoid so-called ghost images due to interference .
Fill transmitter for digital television programs (DVB-T)
With DVB-T and the successor standard DVB-T2 , the use of filler transmitters that work together in a single- frequency network is possible. The use of COFDM means that no frequency conversion is required to avoid interference, as is the case with analog television reception.
Fill transmitter for analog radio on medium wave
The use of radio transmitters that work together in a single frequency network is also possible for the transmission of radio signals on medium wave . In Germany, before and during the Second World War , this technology was used to completely cover the German Empire with as few but very powerful radio transmitters as possible. Until the shutdown of the transmitter Hof (Hohensaas) and the transmitter Würzburg (Frankenwarte) worked in single-wave operation.
Typical transmission powers of a filler transmitter are:
- Medium wave: up to 10 kW
- VHF: up to 1 kW (usually 10 W – 500 W)
- Television: up to 1 kW (depending on the frequency range)