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- This article is about the device used in satellite TV installation, for overcurrent protection devices see Resettable fuse
A typical Ku band universal LNB 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 Integrated 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 in the UK to allow all the residents to receive satellite TV without having to have a separate dish for every resident.
Some multiswitches only have two inputs, in this case, depending on the voltage supplied by the receiver; either horizontal or vertical polarisation is selected.
3 input multiswitches are available, which combine the above with an input from a terrestrial antenna.
5 input multiswitches are also available, which combine the 4 input "standard" multiswitch with an input from a terrestrial antenna.
5x8 (5 by 8) Multiswitches, which have 4 satellite input, 1 terrestrial antennae input and 8 outputs
17x8 (17 by 8) Multiswitches, which have 16 satellite input, 1 terrestrial antennae input and 8 outputs within builtin amplifier for compensating cable losses
- Crossbar switch - generic description of a switch connecting multiple inputs to multiple outputs in a matrix manner.