On Mon, 26 Apr 2004 10:27:39 +0100, "Roger Moss"
wrote:

I have just been rewiring our house and have put a long length of CT100
cable (the stuff from B&Q) down from the loft to under the stairs, plus
further bits from under the stairs to where ever we might want the TV (and
the same for phone and network cabling) and was planning to join the
sections with coax plugs as required.

I was talking to a satellite system installer last week and he said you
could not have any joins in cable from a satellite dish. I really don't
want to hack off the new plaster to put in a single cable all the way down.
Is he right, or can it be joined?

Roger Moss



There are two aspects to this.

- If you are thinking of adding lengths of cable on, this can be done
as long as you use proper 'F' connectors and barrels to do so and make
a decent job. Although introducing a connector, causes some effect
on the signal, if this is for the Astra constellation (carries Sky) in
the UK, then it should be fine as long as only one or two connectors
are used.

- If you are thinking that you can do something like a TV distribution
arrangement with a signal booster, no you can't do that in the same
way as you would for a TV. This is because the receiving element
at the dish - known as the Low Noise Block (LNB) is an active device
with electronics. The satellite transponders deliver signals in
horizontal and vertical polarisations and in two bands - 4
combinations in all. Depending on which channel you are watching and
hence which transponder, the LNB has to be switched by the receiver to
select it. This means a one-to-one relationship between receiver
and a conventional LNB having a single cable.

There are three ways around this.

1) Keep the one to one LNB to receiver relationship and have one
receiver. Distribute the signal out at UHF from that receiver, along
with terrestrial TV to other points in the house. This means one
receiver and one satellite program watched at a time. You could site
the receiver under the stairs because there are solutions to handle
the issue of using the remote - basically a sensor near the TV which
picks up the infra red and passes the electrical signal back along the
UHF coax.

2) You can fit a quad LNB to the dish. This is basically 4
separate LNBs in one case and has up to 4 cables coming from the dish
- each to a separate receiver. Each then runs independently.

3) You can fit a quattro LNB to the dish and run four cables to a
multiswitch (a special kind of head end) fitted (e.g.) under the
stairs. A quattro LNB provides all four signal combinations to the
multiswitch. The receivers, and you could have a lot of outlets if
you want, signal to the multiswitch as though it is a single LNB and
the multiswitch then provides the appropriate signal.
This technique is also used in multi-occupancy dwellings to avoid
needing to have lots of dishes on the roof.





..andy

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