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How a Sky or Freesat Satelitte LNB Works

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 a LNB

To give you some idea of what is happening inside an LNB please refer to the diagram below.

workings of a LNB

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's 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 tone 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 Ban

Each Satellite TV channel that the LNB picks up is on a different band and different vertical or horizontal wave form.
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.