Re: CATV Distribution systems...

["paul gordon" <paul_gordon@xxxxxxx>]

Andy,

Surely the important multiplier would not be the total number of
possible cable channels (which is bound to increase over time -
subject to the bandwidth limit of the cable service), but rather the
total number of viewing locations?...

So let's say we're talking about an "average" sized UK house,
with
cable TV viewing required in the following locations - 3 or 4
bedrooms, lounge, and perhaps kitchen... making 6 viewing locations.

Therefore with 6 cable TV boxes, each fed a baseband signal straight
from the cable service, all required locations would be able to view
all cable channels. (subject to access restrictions of course,) - but
not being a cable user, I don't know whether you would be able to
subscribe once, and then have all your subscription channels allowed
on all your cable boxes - they don't use smart cards for access
control do they?.

I think you'd have a bit of a problem modulating that many channels
onto a distribution system anyway - in the UK only UHF channels 21 -
69 are allocated for this purpose, and in my experience, to avoid
cross-interference, you really need to leave AT LEAST 1 vacant
channel between each used channel - IE dont modulate onto adjacent
channels. This leaves you a maximum possible number of 24 useable
frequencies, LESS those being used by the 5 terrestrial channels
(leaving 19), and less a channel for your DVD player, which leaves a
mere 18 useable frequencies.... And this decreases even more
depending on where you live - if youre in the reception area of any
neighboring TV stations, you'd probably be unable to use any of those
channels either. - Note though, that the above only really applies if
you are feeding a standard UHF aerial into the distribution network,
in order to receive terrestrial channels directly off-air. If
however, you only receive those channels via your cable service, then
you _may_ get away with using their frequencies if your signal is
strong enough, or your UHF cable is sufficiently shielded - remember,
whether you have an aerial or not, your UHF cable itself can still
function as an antenna and pick up enough of those transmissions to
present an image...

This at least is how I understand the situation to be, although I'm
quite possibly barking up the wrong tree.... (I'm no expert!...)

Good luck!

Paul Gordon.


>From: "Andy Powell" <andy@xxxxxxx>
>Reply-To: ukha_d@xxxxxxx
>To: ukha_d@xxxxxxx
>Subject: [ukha_d] CATV Distribution systems...
>Date: Sun, 18 Apr 1999 20:29:35 +0100
>
>Hi,
>
>Does anyone have any idea where I can get a UK compatible CATV
distribution system. Currently we have 2 cable boxes in the house and
I'd like to utilise them to their fullest. Cable charge 6 gbp for
each additional box which in itself isn't a great deal but we have
around 45 channels which would work out at 43*6 gbp so that anyone
could watch any channel... I have found that splitting the signal
before it goes into the Cable box and then merging the output allows
me to view unscrambled channels eg BBC1,2,ITV,CH4,CH5,LWT,RED but
what I'd like to do is distribute each channel on a different RF
frequency so tha any TV/VCR in the house could pick them up. I'd also
like to add the output from the DVD player in the Home Cinema room to
this so DVD's could be watched anywhere in the house too.... along
with the twin VCRs... Am I asking for too much - especially in the
UK....
>
>Andy
>
>
>
>--- Tag-it V1.0 (c) Andy Powell 1998
>Train your child in the way in which you know you should have gone
yourself. - C.H. Spurgeon
>
>
>---------------------------------------------------------------------
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