"spiney" wrote in message
ups.com...
you should be ok with "loftbox" type distribution, see www.tvlink co
uk.

Also, for 30m.

But use satellite grade cable, less lossy, especially if behind
skirting board! Wickes sell 100m drums of rg6u for £20.

Unfortunately, SCART won't work over 30m!

How long can a SCART cable be, then? What about composite?

--
Max Demian

A single lnb can only feed 1 sat receiver, unless multi output, so you
can't "distribute" sat if without multiswitches!

In practice, you can probably run a SCART cable some yards, depending
on any local interference, but at 6Mhz the video signal will get
attenuated somewhat.

In article . com,
spiney writes
A single lnb can only feed 1 sat receiver, unless multi output, so you
can't "distribute" sat if without multiswitches!

In practice, you can probably run a SCART cable some yards, depending
on any local interference, but at 6Mhz the video signal will get
attenuated somewhat.

I've sent RGB over 100m in the past and whilst that distance did require
pre-compensation for loss of high frequencies, testing over shorter
distances, like the o/ps 30m, was fine without. This was for PCs so the
bandwidth was higher than regular TV.

In summary, try scart from an RGB compatible source - not composite -
but expect to have to have cables made up.
--
fred

Unfortunately, SCART won't work over 30m!

Who told you that then? Baseband video works over several hundred metres
if driven correctly into proper 75R coax. It's 10MHz, you know!


I've recently installed a camera using 70m of RG59 and the video
amplitude appeared to be pretty well the same as the other camera,
which was on 20m of cable. And no, the device at the end of the cable
didn't have auto gain adjustment to suit 0.7 to 1.4V, unlike a lot of
modulators. It was a HDD recorder with manual video gain on each input.

I once made up a scart lead (from proper cable that cost a fiver a
metre) that was 17m long and it worked fine. Tee hee, the customer
bought 50m of the cable himself and let me have the offcut, which
raised £150 on eBay!

Bill

On 20 Jul 2005 12:53:58 -0700,
wrote:


Unfortunately, SCART won't work over 30m!

Who told you that then? Baseband video works over several hundred metres
if driven correctly into proper 75R coax. It's 10MHz, you know!


I've recently installed a camera using 70m of RG59 and the video
amplitude appeared to be pretty well the same as the other camera,
which was on 20m of cable. And no, the device at the end of the cable
didn't have auto gain adjustment to suit 0.7 to 1.4V, unlike a lot of
modulators. It was a HDD recorder with manual video gain on each input.

The problem with this sort of thing is that you lose the high frequencies
much more quickly, and that means the chrominance is going to suffer.
Unless whatever is on the end has an Auto-Chroma circuit, then you are
going to need an equalising amp. to bring the the HF back up.

Of course, if this is some ****ty domestic camera, then you may well not
care about HF detail and colour saturation.

spiney wrote:
A single lnb can only feed 1 sat receiver, unless multi output, so you
can't "distribute" sat if without multiswitches!

So you use a ****ing multiswitch then. That's what they're for.

Bill

no, you can't "distirbute" sat if, for that you need a multiswitch
(since only 1 sat receiver can use a single output lnb).

You should be ok with 30m, since this is baseband video out of
receiver, it's the higher frequenct broadcast signals that would be a
problem. But use satellite grade cable.

Paul Ratcliffe wrote:
On 20 Jul 2005 12:53:58 -0700,
wrote:


Unfortunately, SCART won't work over 30m!

Who told you that then? Baseband video works over several hundred
metres if driven correctly into proper 75R coax. It's 10MHz, you
know!


I've recently installed a camera using 70m of RG59 and the video
amplitude appeared to be pretty well the same as the other camera,
which was on 20m of cable. And no, the device at the end of the cable
didn't have auto gain adjustment to suit 0.7 to 1.4V, unlike a lot of
modulators. It was a HDD recorder with manual video gain on each
input.

The problem with this sort of thing is that you lose the high
frequencies much more quickly, and that means the chrominance is
going to suffer. Unless whatever is on the end has an Auto-Chroma
circuit, then you are going to need an equalising amp. to bring the
the HF back up.

Of course, if this is some ****ty domestic camera, then you may well
not care about HF detail and colour saturation.

The facts and practice speak otherwise.

Good quality video coax has a loss of around1db over 30 metres at 10MHz so
the relative loss between the baseband and chrominance is minimal.

Professional broadcasters regular drive 75 ohm RGB or composite signals over
100's metres. At the longer distances the signals are pre-equalised by a few
db to take account of the losses, but for 30metres there should not be any
significant degradation with a flat signal path.