Very basic cabling/distribution advice needed please
 

On 30/12/2012 19:09, David Woolley wrote:


With only four flats, there is a significant risk that the installation
has been done on the cheap. Do you have a copy of the lease. It may give
some hints as to whether the leaseholder has to pay for power to a
distribution amplifier, which I would expect to be present.
If modern practice is followed, there will be four separate cables, from
the head end (not the aerial). Otherwise, the sockets need to be special
ones, which have separate cable inputs and outputs. The worst case
scenario is that the sockets have been simply wired in parallel.

I may be able to gain access to the communal loft and take some images
of the box where the 4 coax goes and feeds our flats, but it's a tiny
hole and am not a tiny bloke and the last thing i fancy is getting the
Mrs to dial 999 for the damm fire brigade to cut my fat arse out out a
loft hatch, I'm sure some of us on here can relate to that especially
just after crimbo



If there is a problem in the distribution system, unless the whole block
is social housing, or it is very new, it is unlikely that you will get
the leaseholders to agree to fix it.
It is all social housing and they are responsible for providing a TV
signal to the flats, however i guess it's like BT and there liability
stops at the socket, if TV's work from that point (and they do) then
anything after that is down to me, hence why i skimped on coax before,
but i will do my bit first and buy decent coax and any suggested
hardware and if i still have issues then i'll call them in and see what
they say but i suspect it will be down to me.

Jim

Very basic cabling/distribution advice needed please
 

On 30/12/2012 18:37, charles wrote:
In [email protected] .com,
wrote:
OK I'll be upfront I know very little about this so please bear with me
as I'm well out of my comfort zone here.

I live in a small block of 4 flats and we all get our TV signal from the
same external aerial and gets it's feed from Crystal Palace, the cable
comes in the roof and is then feed to all four flats where we have a
single UHF TV socket, something like this
http://m2.sourcingmap.com/smapimg/en...ite-28245n.jpg

What I want to be able to do is use that single socket and feed 3 other
TV's in the following order (which I presume is the best way to do it)
the socket is in the living room so I will of course run cable from the
socket to the TV then I use a very cheap Argos splitter to split the
signal so one goes to the TV (well sky or free-view box not too sure
which one, but it ends up in the TV somehow).
Then from that splitter I run some cheap White plastic coated coax to my
desk which is in the kitchen (my flat is the kind where living room and
kitchen dining room are all in one, so where dining table should be is
my desk) on my desk I have one of those 10" Nikkai LCD TV's, then I
wanted the TV signal fed into my bedroom which again is done right now
via cheap white plastic coated coax, which then goes into an old labgear
TV booster

http://img138.imageshack.us/img138/5...4ds1bqls4k.jpg

which then goes into free-view box then TV.
So that is how it's set up now but I'm sure something is wrong somewhere
as I retuned my 10" the other day and it only found a few channels then
when I set up Samsung in the bedroom it failed to find any HD channels
(it's a Samsung UE32ES5500), now I'm presuming that the 10" and 32" were
not able to find all channels due to poor signal, so I have come to the
decision I need to look into a better way of rewiring the flat for TV
signals.

I don't know if I should just replace the coax with some decent stuff or
look at some form of wireless distribution system, I don't have a
fortune to spend maybe £50-£100.

I have no access to the aerial itself of the distribution box the
engineer has put in I can only work on things from "within" my flat, I
know 2.4Ghz is busy to say the least I have cordless Panasonic phones x
3 plus, cordless headphones but these are only on 860 odd Mhz and an old
O2 wireless router v4.

I will post a picture of the TV antenna itself on Monday, just in case
that makes any difference, any and all advice is welcome.

There could be a number of problems, so it's not going to be easy to give
an instant answer. However, i suspect that your second amplifier (old
labgear TV booster) might be one of them. I don't see the need for it, and
it might well be overloading.

First: take each tv set in turn to the incoming socket and feed it directly
- then tune it. Then try each set simply via the lenght of cable you've
already got in place. Does it work then? That will eliminate the cable.
If you get problems, yes, replace the cable with some decent stuff. You
don't mention the lengths, but I can't imagine the runs being very long.

You'd be better off getting a 4 outlet amplifier rather than having one
following another.

I only have a single booster which is in the bedroom before it goes in
the TV, which i now know is in the wrong place.
OK the main TV in the living room is fine as the feed is only some 8
feet from socket, i took the 10" and 32" the the UHF socket and tuned
them in there and got all my channels including the HD ones on the
Samsung, then put them back in the normal place (desk and bedroom) and
desk TV will only pick up a few channels (ITV3 stuff like that) but not
much else and TV in bedroom gets no HD feed whatsoever, so I presume we
can work on the basis of my cabling has died and I need to buy some new
coax.

I guess what i need to do is find a place to get the CT100 and the
various plugs, i'm guessing so long as i don't buy the cheapest plugs
then just middle of the road stuff will do or should i be looking out
for a certain brand to buy?

Jim

Very basic cabling/distribution advice needed please
 

Jim wrote:

It is all social housing and they are responsible for providing a TV
signal to the flats, however i guess it's like BT and there liability

You are right that the responsibility stops there. The advantage of
social housing is that they do actually carry out repairs, usually
relatively promptly, and they will have experience with dealing with
contractors. In a privately owned, particularly self managed,
environment, and particularly where it has gone to buy to let, it may be
too difficult to get the management to spend anything on TV distribution.

As it happens, it looks like there is an adequate signal at the wall
plate, but just not enough margin to cope with 16 to 20 dB of additional
attenuation (assuming resistive splitters).

stops at the socket, if TV's work from that point (and they do) then
anything after that is down to me, hence why i skimped on coax before,
but i will do my bit first and buy decent coax and any suggested
hardware and if i still have issues then i'll call them in and see what
they say but i suspect it will be down to me.

Very basic cabling/distribution advice needed please
 

David Woolley wrote:

As it happens, it looks like there is an adequate signal at the wall
plate, but just not enough margin to cope with 16 to 20 dB of additional
attenuation (assuming resistive splitters).

The OP mentioned that the signal from the tx is obscured by buildings,
and that the aerial is on a twenty foot mast. That suggests that the
signal quality (as opposed to quantity) might not be too good. The
relevance of this is that (supposing that the signal levels delivered by
the outlet are high) as they fall due to the horrendous daisychain
within the flat, the level at which reception problems will arise will
be higher than it would otherwise be, because if the signal is already
corrupt, as the signal starts having to compete with the receiver's
noise reception will suffer at a higher level. In other words, a really
clean signal will provide good reception at a lower level than a corrupt
one.
It is also likely that in a screened location there will be signal level
variations within the muxes. There might even be deep notches. These
things will vary unpredictably with time, and it is quite possible that
something that has happened some distance away has, (in a straw breaking
a camel's back way) caused the recent reception problems. The ability of
a receiver to tolerate a notch within a mux depends partly on the
general signal level. As levels drop a larger and larger portion of the
mux has an unusable s/n ratio. You can imagine how the daisychain in the
flat can affect this.
Talking of notches, there seems to be plenty of scope within the flat
for mismatches and reflected signals.
Going back to the signal delivered by the distribution system, it sounds
as if there will be some sort of amplification. Since the system
pre-dates DSO there is probably excessive gain. The signal overload at
the amp (and possibly at equipment within the flat) will degrade BER;
each successive stage degrading it a little more. It is a strange
paradox, but the OP is probably suffering simultaneously from too much
and too little signal!
As a general point, I feel that it is foolish to attempt a diagnosis in
this case by remote control. The list of possible faults is far too
long, and they will be interacting of course. When I drive towards a job
that has been described as being something similar to this one, I
sometimes amuse myself by hypothesising about the likely outcome. I'm
usually wrong, in the event. The only good advice is that which has
already been given: rip it all out and start again! And even then the
quality and quantity of the incoming signal remains unknown, so there
still might be problems.
The fact is, after five minutes on site with an analyser, any half
decent installer would be drinking the tea. For that reason a long-drawn
out dialogue containing endless suggestions and hypotheses seems utterly
pointless to me; in fact it makes me tired just reading it. Sorry, but
that's how it seems to me.

Bill

Very basic cabling/distribution advice needed please
 

On 30/12/2012 19:08, Graham. wrote:


Wirless TV senders is the spawn of Satin, use cable, not cheap cable
but "Satellite grade" CT100 or equiv.


Bill's article on cable is worth a read.
http://www.wrightsaerials.tv/article...-quality.shtml

Also ensure any splitters are fully screened
http://www.admac.myzen.co.uk/Splitter/


--
mailto:news{at}admac(dot}myzen{dot}co{dot}uk

Very basic cabling/distribution advice needed please
 

Bill Wright wrote:
It is also likely that in a screened location there will be signal level
variations within the muxes. There might even be deep notches. These
things will vary unpredictably with time, and it is quite possible that

I can certainly appreciate that, as we have that problem. It's one of
the main reasons why I said that the exact location would be needed.

Unfortunately we are in the privately owned, gone to buy to let,
situation, not the social landlord one, so, especially as the decision
makers are non-resident, or cable users, no-one is willing to spend
anything to investigate the problem properly.

Very basic cabling/distribution advice needed please
 

"Jim" wrote in message
...
On 30/12/2012 18:57, R. Mark Clayton wrote:

How far are you from Crystal Palace?



Well as the crow flies* I'm 5.435 miles or 8.338 km away from the palace
however my signal is being blocked to "some" degree by other flats, I'm
2nd floor and aerial is on a T&K bracket with about a 20 foot pole.

There should be loads of signal* and, assuming that the aerial has more than
one element , no need for amplification in the landlord's demise. You
probably won't need it in yours unless the landlord's split is rubbish.




You have 200kW at ~8km whereas I have 100kW at 30km, so you have 30 times
more signal or nearly +15dB before you start. You also have channels at the
bottom of the band, which means less loss in your cable runs.




* TV signals don't usually go any other way unless you have multi-path
reflections.

Very basic cabling/distribution advice needed please
 

R. Mark Clayton wrote:

Well as the crow flies* I'm 5.435 miles or 8.338 km away from the palace
however my signal is being blocked to "some" degree by other flats, I'm
2nd floor and aerial is on a T&K bracket with about a 20 foot pole.

There should be loads of signal* and, assuming that the aerial has more than
one element , no need for amplification in the landlord's demise. You
probably won't need it in yours unless the landlord's split is rubbish.

Unfortunately, these systems are often installed to a formula, and the
formula includes an amplifier, whether needed or not. Many times I've
seen a 20dB amp with two 12db attenuators in front of it!

Especially as we have now had DSO it is becoming routine to remove
amplifiers from the very small systems.

Bill

Very basic cabling/distribution advice needed please
 

R. Mark Clayton wrote:


There should be loads of signal* and, assuming that the aerial has more than
one element , no need for amplification in the landlord's demise. You probably won't need it in yours unless the landlord's split is rubbish.

A landlord should use a system with more isolation between outlets than
is required within a single residence. That is typically done by using
taps with upwards of 10dB attenuation.

You have 200kW at ~8km whereas I have 100kW at 30km, so you have 30 times
more signal or nearly +15dB before you start. You also have channels at the
bottom of the band, which means less loss in your cable runs.

He also does not have line of site on the transmitter.

Very basic cabling/distribution advice needed please
 

David Woolley wrote:
R. Mark Clayton wrote:


There should be loads of signal* and, assuming that the aerial has
more than one element , no need for amplification in the landlord's
demise. You probably won't need it in yours unless the landlord's
split is rubbish.

A landlord should use a system with more isolation between outlets than
is required within a single residence. That is typically done by using
taps with upwards of 10dB attenuation.
In practice nowadays it is quite usual to use four-way splitters to
provide four feeds. These might or might not be fed from a tap-off line
via low value taps (eg a 12dB tap feeding a four way split = four 20dB
taps). All very old fashioned nowadays of course. New terrestrial-only
systems are very rare.

Bill