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How a Sky LNB Works



How LNBs Work

The Sky or Freesat Satellite Dish LNB
 picks up the signal from the dish and relays it down the cable to your satellite box.

LNB= Low Noise Block

It sits on the end of the arm coming out from the dish.

                                       The satellite signal is reflected from the dish to the LNB which picks up 4 signals.

             Picture of an LNB

To give you some idea of what's happening inside an LNB you will see a diagram below.
 
                                 
Picture of a diagram of the workings of a LNB


The signal from the satellite dish enters the feed horn of the LNB in a horizontal and vertical waveform.
The LNB picks which waveform it is going to use by a voltage that is sent up the dish cable from the satellite receiver.
This is 18 volts for the Horizontal waveform and 14 volts for the vertical waveform.   

Then to change from higher band to lower band the satellite receiver sends a 22 kHz signal to a switch that is inside the LNB that switches between the lower and higher bands.

So what we end up with at the end of the cable is as follows

Horizontal High Band
Horizontal Low Band
Vertical High Band
Vertical Low Band
 The different Satellite TV channels that the LNB picks up are on different bands and different vertical or horizontal wave forms.
So when you are changing TV channels on your satellite receiver there is constant switching of lower and higher bands plus voltage switching for the horizontal and vertical wave bands between the satellite receiver and the LNB.