The LNB on the end of the satellite dish picks up either a horizontal or a vertical signal. Your satellite receiver sends an 18volt current to the LNB when it requires a horizontal signal and a 13volt current for a vertical signal. Physically turning the LNB on the end of your satellite dish 90degrees will also alter the signal being received from Horizontal to Vertical. Any where in between these two positions and the LNB will pick up a mixture of both signals. This is known as “Cross Polar Discrimination” and causes interference in the signal quality being received.
Due to the curvature of the earth and the position of the satellites in orbit, the LNB often needs to be at a very slight angle. As you travel around Europe in your caravan or motor home, the correct skew position of the LNB changes very slightly.
The main effect of the LNB being out of Skew is a reduction in the “Signal Quality”. The easiest way to make adjustments with out a spectrum analyser is to slightly adjust the LNB and then check the satellite signal quality reading on your Sky or freesat box. If you have a look at a professionally installed sky satellite, you should notice that the cable is attached to the LNB at a slight angle.