Extending Terrestial Digital Over Cat5 to Multiple TVs/Receivers

On Wed, 29 Aug 2007 09:55:06 +0100, "Paul D.Smith"
mused:

...snip...
No, if they were any good they would have installed enough cat5e
points for it's intended use, which is what they di by the sound of
it. Whoever wanted the TV distribution would have had CT100 installed
alongside the cat5e.

Where exactly would you leave these 'pull ropes', assuming this is a
domestic install?

Well Cat5e is already becoming obsolete (Cat6 and GB Ethernet) so personally
I'd have left a nylon rope within the conduit - until I remembered about
pulling). And even than I'd probably leave one for possible "guiding".

Have you ever installed cat5e on a professional basis?

Umm, on second thoughts they may not have left "pull ropes" as pulling
Cat5e
is bad for the cable and frowned upon.

Erm, how exactly do you install cat5e then? Gently lay it in it's
final position by completely demolishing homes and offices so you can
gain access to 100% of every cable run?


It's a very good question. I believe you have to "push" it through as
you're installing the conduit, assuming that you can't get to the conduit
later.

How do you get it out of the box then?

This is clearly less of an issue in offices where, for example, the
cable is laid under a false floor (as I'm sitting on at the moment) but more
difficult in a home.

The issue is that Cat5e is quite fine wire and easily damaged. You'll
probably still get a connection but depending on the damage, crosstalk etc.
result in far lower that 100Mbps that you expect. This is an issue for high
bandwidth applications like media (video) serving.

********.

Also means I'm slightly screwed when running cat5e through ducting.
Gonna have to start using 7' dia ducts now so I can gently carry the
cat5e through and carefully lay it in.

Make nice gentle curves (as is recommended anyway) and make sure you have
regular inspection points so you only have relatively short distances to
push the cable through. Solid core Cat5e is stiff enough for that normally.

With someone pushing, you're probably OK with someone "guiding" (pulling
just enough to maintain the correct direction of travel) rather than
actually dragging the cable thorough.

I'd be interested to see some actual measurements of Cat5e performance on
good and bad installs but sadly few "installers" actually carry the tools to
do such measurements so unless something goes wrong, you never find out.

However its worth pointing out that video etc. requires very high bandwidth
so media servers will be far more sensitive to cabling issues than data
servers.

I'm going to have to check through soe of your other posts. I was
under the impression you were reasonably sane.
--
Regards,
Stuart.

It's a very good question. I believe you have to "push" it through as
you're installing the conduit, assuming that you can't get to the conduit
later.

How do you get it out of the box then?

Umm, you've honestly got me there. I'm off to read up more and also talk to
the guys that install our cable here. The only thing that springs to mind
is the difference between the sometimes quite strenuous efforts used to pull
mains cable when installing, which Cat5e won't take, compared to the
expected relatively gentle pull required to unroll it out of a carefully
wound box.


This is clearly less of an issue in offices where, for example, the
cable is laid under a false floor (as I'm sitting on at the moment) but
more
difficult in a home.

The issue is that Cat5e is quite fine wire and easily damaged. You'll
probably still get a connection but depending on the damage, crosstalk
etc.
result in far lower that 100Mbps that you expect. This is an issue for
high
bandwidth applications like media (video) serving.

********.

Which bit, the crosstalk/low speed if damaged or video wanting high
bandwidth?

I'm going to have to check through soe of your other posts. I was
under the impression you were reasonably sane.

When I've taken my meds ;-). Seriously, I'll try and dig out some refs. for
you as I've come across this info. on the web often, especially when I was
considering how easy it would have been to cable my 1920s house (bloody hard
without ripping it apart or leaving exposed cables was the answer).

Paul DS.

"Paul D.Smith" wrote in message
. ..
It's a very good question. I believe you have to "push" it through as
you're installing the conduit, assuming that you can't get to the conduit
later.

How do you get it out of the box then?

Umm, you've honestly got me there. I'm off to read up more and also talk
to the guys that install our cable here. The only thing that springs to
mind is the difference between the sometimes quite strenuous efforts used
to pull mains cable when installing, which Cat5e won't take, compared to
the expected relatively gentle pull required to unroll it out of a
carefully wound box.


This is clearly less of an issue in offices where, for example, the
cable is laid under a false floor (as I'm sitting on at the moment) but
more
difficult in a home.

The issue is that Cat5e is quite fine wire and easily damaged. You'll
probably still get a connection but depending on the damage, crosstalk
etc.
result in far lower that 100Mbps that you expect. This is an issue for
high
bandwidth applications like media (video) serving.

********.

Which bit, the crosstalk/low speed if damaged or video wanting high
bandwidth?

I'm going to have to check through soe of your other posts. I was
under the impression you were reasonably sane.

When I've taken my meds ;-). Seriously, I'll try and dig out some refs.
for you as I've come across this info. on the web often, especially when I
was considering how easy it would have been to cable my 1920s house
(bloody hard without ripping it apart or leaving exposed cables was the
answer).

Paul DS.


Before going into detail, I am an IT specialist and whilst cabling is not
where my main source of work lies, I do occasionally perform network cable
installations professionally. Referring to the original query and not being
a TV specialist, I don't know of any current technology that would allow
standard TV signals to be sent over Cat 5e cabling, but of course it can be
done to a certain extent using a network based media centre or computer
media centre and using data streaming over a computer network. However I
don't think that's what the original poster was after.

OK - Cat 5 cable is made of of 4 twisted pairs (8 individual wires) and the
quality of the cable can vary - particularly in terms of flexibility and
strain relief or the nylon fibre that runs alongside the pairs within the
outer cable sheath. Installing new cable into existing conduit can
sometimes be a bit tricky depending on the size and condition of the
conduit, whatever else might be in the conduit as well (ideally, nothing
else should be in the same conduit as network cables) and any sharp corners
or bends in the conduit. A 'pull rope' left in the conduit can be used to
gently guide the new cable, but obviously excessive force should not be used
or the inner twisted pairs may be damaged by breaking - a risk that is much
higher if poor quality cable is used. Installing new cable into existing
conduit is ideally a two person job and where there can be an element of
pulling by one person and pushing/feeding by the other and ideally a new
'pull rope' should be istalled at the same time as any new cable for future
expansion.

The way Cat 5e cable is usually packed into 300m boxes by the manufacturer
means that it does not always feed from the box as freely and neatly as it
would do from a reel, and there can be a tendency for the cable to loop and
kink occasionally which can cause it to snag. Obviously the person at the
'box' end can deal with this issue as it occurs and ensure that the new
cable feeds into the conduit reasonably freely. Where a second person isn't
available to assist, the cable will have to be pulled rather than pushed in
most cases, so great care should be exercised in not pulling so hard or
sharply that the cable could be damaged. In most cases, Cat 5e is strong
enough to tolerate mild abuse, but wherever possible it should be treated
with due respect in that if it doesn't feed reasonably freely, it's usually
caught or snagged on something and the installer needs to sort out the
issue, It's not rocket science.

Cat 5e is UTP or Unshielded Twisted Pair cable. The purpose of the twist in
every twisted pair of wires is to promote noise cancellation and the
rejection of electrical interference from outside sources. How much
interference might be caused depends entirely on local conditions. The
pitch of the twist is important and somewhat different to the twist in
normal telephone cable, thus telephone cable is not recommended for computer
networks, but Cat 5e can be used for telephone system wiring and is often
recommended by BT engineers for phone extensions.

If one of the internal wires inside the Cat 5e cable does get broken for any
reason it may still be possible to get away with using the cable as only two
of the four pairs of wires are actually used in a normal network scenario
and as long as Power Over Ethernet is not an issue, it is possible to create
a properly working connection even though it would be considered somewhat of
a 'bodge'. A sound electrical connection from end to end, but not correctly
using twisted pairs as intended may or may not work over short distances
with some inevitable degradation in signal due to crosstalk/induced noise
etc..(how bad this would be depends entirely on the local sources of
interference), but over longer distances approaching the 100m recommended
cable run limit, I wouldn't necessarily expect a good network connection,
and in any case doing it this way would be plainly wrong. If ever in a
situation where the integrity of a length of Cat 5e cable has been
compromised or is suspected of being compromised, a new length of cable is
the proper answer, but as long as two pairs of wires are intact within the
cable, these *can* be used to carry signals between devices on the network
over the recommended maximum distances without compromise just as if the
whole cable was intact. Using 4 wires from 4 separate pairs or mixing and
matching and ignoring the pairings would not provide the recommended level
of noise cancellation that using the correct pairings does and because of
this, crosstalk, external interference would almost certainly present
problems.

Nick

How do you get it out of the box then?

Umm, you've honestly got me there. I'm off to read up more and also talk to
the guys that install our cable here. The only thing that springs to mind
is the difference between the sometimes quite strenuous efforts used to pull
mains cable when installing, which Cat5e won't take, compared to the
expected relatively gentle pull required to unroll it out of a carefully
wound box.

You should see what the paddies get up to installing multipair phone
cables. Sometimes several pairs are unusable!....

--
Tony Sayer

Cat 5e is UTP or Unshielded Twisted Pair cable. The purpose of the twist in
every twisted pair of wires is to promote noise cancellation and the
rejection of electrical interference from outside sources. How much
interference might be caused depends entirely on local conditions. The
pitch of the twist is important and somewhat different to the twist in
normal telephone cable, thus telephone cable is not recommended for computer
networks, but Cat 5e can be used for telephone system wiring and is often
recommended by BT engineers for phone extensions.

The different "twists" are to prevent pair to pair crosstalk ..FWIW...

--
Tony Sayer

On Thu, 30 Aug 2007 08:45:51 +0100, "Paul D.Smith"
mused:

It's a very good question. I believe you have to "push" it through as
you're installing the conduit, assuming that you can't get to the conduit
later.

How do you get it out of the box then?

Umm, you've honestly got me there. I'm off to read up more and also talk to
the guys that install our cable here. The only thing that springs to mind
is the difference between the sometimes quite strenuous efforts used to pull
mains cable when installing, which Cat5e won't take, compared to the
expected relatively gentle pull required to unroll it out of a carefully
wound box.


This is clearly less of an issue in offices where, for example, the
cable is laid under a false floor (as I'm sitting on at the moment) but
more
difficult in a home.

The issue is that Cat5e is quite fine wire and easily damaged. You'll
probably still get a connection but depending on the damage, crosstalk
etc.
result in far lower that 100Mbps that you expect. This is an issue for
high
bandwidth applications like media (video) serving.

********.

Which bit, the crosstalk/low speed if damaged or video wanting high
bandwidth?

Pulling a cable in the methids you describe will not cause any
problems. Excessive force will damage a cable, but so far all that
you've described are normal installation methods.

I've installed thousands of cat5e cables and had the analyser on most
of them and had the odd wiring error and dodgy termination but never
had a cable fail on any other criteria. Some of them I've not expected
to pass as they have been dodgily installed as temporary measures.

I'm going to have to check through soe of your other posts. I was
under the impression you were reasonably sane.

When I've taken my meds ;-). Seriously, I'll try and dig out some refs. for
you as I've come across this info. on the web often, especially when I was
considering how easy it would have been to cable my 1920s house (bloody hard
without ripping it apart or leaving exposed cables was the answer).

Paul DS.

--
Regards,
Stuart.

On Aug 30, 11:53 am, "nickm" wrote:
"Paul D.Smith" wrote in message

. ..



Before going into detail, I am an IT specialist and whilst cabling is not
where my main source of work lies, I do occasionally perform network cable
installations professionally. Referring to the original query and not being
a TV specialist, I don't know of any current technology that would allow
standard TV signals to be sent over Cat 5e cabling, but of course it can be
done to a certain extent using a network based media centre or computer
media centre and using data streaming over a computer network. However I
don't think that's what the original poster was after.



There are at least 2 devices available that will enable high
definition video in either RGB or component video form, plus SPDIF
sound, to be passed over Cat 5 cable (see
http://www.tekcare.co.uk/Scripts/pro...idproduct=1004 or
http://www.kat5.tv/modules.html).

However these assume centrally located digiboxes, with the above
devices routing the outputs (A/V) over Cat5 to the displays.

Given that most modern TVs now come with an inbuilt digibox I was
wondering whether there is any way of routing the raw signal over Cat5
to avoid having to buy separate digiboxes (one per TV) and locate them
centrally.

Sounds like this isn't possible given the responses to date?

Thanks

Nigel