dazzaessexuk said:
new here and to satellite could anyone explain how you alter the channel frequencies that appear in what satellite magazine so my meter will understand them i know you have to subtract 9.750 and i think 10.600 from them but can anyone point me in the direction of the information of why we do this and for what lnbs is it deduct 10.600 for vh and hh and 9.750 for vl and hl and what the cut off is for low and high band , please help me get my head around this many thanks
Well,
The signal frequencies transmitted in ku Band from the satellites range from 10.7 GHz to 12.75GHz.
However to get this bandwidth down the cable it is split into two bands:- Low band-10.7 GHz to 11.8 GHz and High band 11.6 GHz to 12.75 GHz.
The band selection is performed within the Universal LNB using a mixer and a local oscillator.
The LNB contains two local oscillators:- one at 9.75 GHz and the other at 10.6 GHz.
The purpose of the mixer and LO is to downconvert the signal that the dish gets (10.7 GHz to 12.75 GHz) to a much lower frequency, that will not suffer such severe attenuation in the cable as the higher frequencies.
For example
10.7 GHz to 11.8 GHz ->> 950 MHz to 2.05 GHz
11.6 Ghz to 12.7 GHz ->> 1 GHz to 2.15 GHz
The switching point is around 11.7 GHz
The switching is normally initiated by the receiver by sending a 22kHz tone to the LNB, with no tone it is low band, with the tone it is high band.
Robbo