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Multifeed is a gadget for reception of a signal from several satellites without turning a dish. It is possible to realize it in several ways:
In any case a device with the strange name 'DiSEqC Switch' is used. They are of two types:
The circuit (scheme) of connection is very simple:
Ideal variant (but also most expensive) - each dish has its own converter. This way of connection sometimes happens to be unique possible. For example, when it is necessary to receive signals from satellites carried rather far apart (for example, 36°E AND 4°W).
But, if the satellites are located close (5°E and 4°W, 13°E and 5°E, 13°E and 19°E) and there is a reserve of signal's level for some of them, it is possible to put some converters on the same dish (for example, I receive in Minsk 13°E, 7-5°E and 4-5°W simultaneously). In such a case the dish is oriented to the satellite with the weakest signal as usual. This signal will be received by the converter in focus of a dish. The side converters will receive signals from other satellites. The right converter will receive the satellite which is located to the left of main satellite, left converter - which is located to the right of main satellite.
Certainly, the signal on the side converter will come to the side converter not so well focused, as to main converter. Footprints of the signals have the approximately following view in a plane of converters:
When using usual LNBF, an exciter of the LNBF gets only part of the signal. So, the signals from side satellites turns out rather strongly weakened. To take the most of a side signal, it is useful to use converters with special exciter which is wider than usual LNBF has. An exciter is like megaphone, which collects signal for converter. However, it is necessary also to take into consideration, that the signals from other satellites, which are taking place on a neighbourhood with satellites necessary for you, will be washed away also and footprints of their signals will partly cover footprints of needed signals.
Usually adjacent satellites have no signals with identical (or close) frequencies and one polarization, but with different polarizations - a lot. Therefore accuracy of a corner of an inclination of side converters becomes even more important, than for the central converter. In case of incorrect corner of an inclination, signals from two satellites will come simultaneously and even with large level of a signal it's quality will be very low, down to 0.
It is necessary also to take into consideration that the satellites are also at different heights. Therefore, it's necessary to install the converter lower for higher satellite.
The setting up different receivers is carried out differently. Main operations are:
Now when switching channels the necessary converter will be used automatically.
Below you can see the photoes of multifeed for 2 satellites (Eutelsat W4 (NTV +) and HotBird) which were made by Alexander Koryagin from Moscow.
