Multiswitch TV signal distribution in Llantrisant
A multiswitch is a device used with a dual or quattro LNB to distribute satellite TV signals to multiple (usually more than four) receivers from a single dish and LNB.
A typical Ku band universal LNB designed for the European market can be switched between four modes (two frequency ranges and two polarisations) selected by signals from the receiver (supply voltage for polarisation and presence or absence of a 22 kHz tone for frequency range). This means that each receiver needs a separate feed and twin-tuner receivers (such as SKY and Freesat) need two separate feeds. For small numbers of receivers a multi-output LNB is used and all the feeds are taken straight from the LNB but there is a limit to the number of outputs that can reasonably be placed on a LNB.
So for larger installations a quattro LNB is used in conjunction with a multiswitch. The quattro LNB provides the signals for all four of the modes at the same time. The multiswitch then selects which of these signals to send to each receiver . For very large installations the signals from the LNB can be split and fed to more than one multiswitch. Typically a larger dish is used to make up for the extra losses in the longer cable runs and the multiswitches.
Some multiswitches can also mix in terrestrial TV and FM radio signals which can then be split out again by a special faceplate (known as a triplexer). Such Intergrated Reception Systems allows satellite, TV and radio service to be supplied down a single cable saving on installation costs.
Multiswitches are commonly installed on or in blocks of flats to allow all the residents to receive satellite TV without having to have a separate dish for every resident.