[mythtv-users] slightly OT - DVB-S question

Matthew Geier matthew at sleeper.apana.org.au
Thu Feb 2 10:05:11 UTC 2006

Nick Rout wrote:
> If I have two DVB-S devices connected to  one satelite dish, does the
> dish need two LNB's? (Obviously i would want each device to be tuned to
> a different channel, but all channels on the same satellite.)
> If it matters one device will be a sky set top box, the other will be a
> PCI DVB-S card.

  Can be done, but the only one device can power/control the LNB. I've 
got 6 STB's connected to the one LNB at work. (8 way splitter, power 
injected by a power injector for the LNB). All STB's on this one are 
actually tuned to the same transponder, recieving different programs off 
the multiplex. I have another daisy chain configuration where two boxes 
are tuned to different transponders but both are vertical transmissions.

  So the first device in the chain gets to control the mode of the LNB 
(Horizontal or Vertical) and the other box just has to make do - if the 
first box is set to Horizontal, the 2nd can only get transponders that 
are also Horizontal polarized, when it tries to tune the vertical 
transponders, it won't be able to get the LNB to change mode, so those 
transponders won't get signal lock.

  You can get dual LNBs so you can use the one dish but each receiver 
gets to fully control it's own LNB.

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