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satellite multiswitch design

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young.microwave.eng

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Dear roommates
I.d like to design some satellite multiswitch that you can feed several receivers through some limited dish antennas.I need primary knowledge about different LNB and about the communication between receiver and LNB.
would you please help me find some tutorial about them
thanks in advance
 

I can recommend a book by Nick Beer: Servicing satellite V equipment, Newness, Oxford, UK, 1998.

In principle, any LNB converts the C-band or Ku-band spectrum to the IF spectrum, 0.95-1.45 GHz(US), or, 0.95-2.15 GHz (other world) which is fed to the indoor receiver unit.
A symmetrical od offset parabolic dish can be pointed to only one satellite, and by mechanical drive, to other satellites on GEO orbit. In the US, ugly unsymmetrical dishes can hold up to five LNBs, in a "focus" line, so by one dish the multiple LNBs can receive signal from up to five satellites without moving the dish.

Then you can use a switch or a combiner to use all five IF signals in one or more receivers. The IF cables also carry DC power to LNBs, and some LNBs can switch input-signal polarization by setting the DC voltage, usually +13 V for one polarization, +16 V for the other. To set local-oscillator frequency in some tunable LNBs, a 22 kHz signal is sent to the LNB, to switch one or another LO frequency.

Some modern LNBs, for LO frequency locking, use the IF line also to send a 10 or ~100 MHz signal to the LNB, on which the LO frequency locks and the complete receiver is so stabilized.

Possibly a good way to get the updated information would be to consult satellite equipment installer(s) who have details on your local receivers. Many TV and other programs are coded, which makes tinkering difficult. The particular receiver only opens for a particular signal (program) upon paying for it- this directs a confirmation command by phone to the receiver.
 
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