Advice, please

"Adrian C" wrote in message ...
On 21/04/2010 19:13, critcher wrote:
so what is the greatest distance a quad lnb standard sky dish can operate
from with a decent signal strength ?

Most do 36,000 km



Can't argue with that :-)
--
Graham.

%Profound_observation%

The system will have to feed my apartment to start with, with the
maximum need to feed up to 115 flats and apartments, some of might
want more than one outlet e.g. for a TVs in the living room and
bedroom etc.

Still wondering what those different types of LNB do!



John, I am no expert on Sat distribution systems, but this worries me on at least two
fronts.
Firstly, who put this constraint in place that the satellite "head end" should be in
yours, or anyone else's flat? Was it you, or your contractor?

This is most unusual. Where is the existing aerial distribution point? Surely that
is where the additional kit should be.
Presumably additional cables are going to be run to the individual flats from here.
That will constitute the bulk of the work involved.

I have read about these optical LNBs they are quite new and very possibly the
way forward for the future, but right now this kit is very specialised, very
expensive and hardly anyone has any experience of using it.

If the fibre needs to be spliced and terminated then its even more specialised.

Add to that the fact the outdoor bit (the LNB itself) will be exposed to our British
climate.

Will it be so difficult to run 4 conventional co-ax cables?
Blocks such as yours are routinely installed with a conventional Quatro and cables.

I will be interested to hear Bill's thoughts on this.

--
Graham.

%Profound_observation%

I wonder what satellites you will be recieving if you are expecting a
"couple" of dishes to be installed?

I am also just a little bit wary of fibre optics at the moment.
Probably as I haven't used them yet!
In general the principle seems fine and the great advantage is the low
loss and ability to split the signals to many more outlets.
It is only the main runs which are fibre optic, and then conversion is
back to standard electrical at the local distribution points.
To me, it seems that the main problems are having to use preset
lengths of fibre optic cable, as terminating is difficult, and
possible inexperience of installers if you don't get the right ones.

On Wed, 21 Apr 2010 14:30:54 -0700 (PDT), widgitt
wrote:

I wonder what satellites you will be recieving if you are expecting a
"couple" of dishes to be installed?

I am also just a little bit wary of fibre optics at the moment.
Probably as I haven't used them yet!

I've been using optics for over 20 years - they are quite robust, but
as to how they will perform in this particular application has yet to
be seen.

In general the principle seems fine and the great advantage is the low
loss and ability to split the signals to many more outlets.

The fibres themselves are very strong and will not suffer from water
ingress. The literature I've seen indicates the fibres are terminated
in FC/PC connestors - these connect by means of a screw thread and are
made out of metal (steel?) so tend to be far more robust than the
newer type of connector - which are made from plastic

It is only the main runs which are fibre optic, and then conversion is
back to standard electrical at the local distribution points.

The design appears to indicate fibre all the way to the TV set -
http://www.triax.co.uk/Products/Fibr...Solutions.aspx


To me, it seems that the main problems are having to use preset
lengths of fibre optic cable, as terminating is difficult, and
possible inexperience of installers if you don't get the right ones.

Preset lengths are the way to go. There are self terminating optical
connectors available, but they're not something I would use.


--
Cheers

Peter

(Reply to address is a spam trap - pse reply to the group)

On Wed, 21 Apr 2010 04:36:31 -0700 (PDT), John wrote:


Thanks!

John Porcella

I can't find the end of your message. Where is it?

Why, are the distances -that- great?

Yes. *It is a twenty-one story building, with long corridors.

Assuming 10ft per floor and 100 foot corridors, longest distance
will be 310 ft from dish, that's nothing

Also, I was told that this method would not be subject to
interference, nor would it interfere with the existing communal TV
system, even though the cables would run next to each other down the
dry risers.

Use good screened coax it won't be a problem, using fibre is just an
excuse to cause expense

I suspect that you are right!

Would there not, though, be a saving in that the dishes would not have
to be as big and no need for amplifiers down the line to cope with
losses?

How much more expensive, per metre, is fibre optic cable compared to
traditional co-axial?

Thanks very much indeed for your input.

John



Steve Terry
--
Get a free Three 3pay Sim with £2 bonus after £10 top uphttp://freeagent.three.co.uk/stand/view/id/5276

On 21 Apr, 16:27, "John Legon" wrote:
"Roger R" wrote:

http://en.wikipedia.org/wiki/Low-noise_block_converter

An interesting article which makes a point that I had overlooked, namely
that
most LNBs are kept powered because this helps to stabilise the temperature
and hence the local oscillator frequency.

Well, if you're switching between four LNBs as I am, only one LNB receives
power at a given time, leaving the others to go cold so to speak. *This
doesn't matter at all for DVB-S HD and SD signals, but when switching to an
LNB for a DVB-S2 HD broadcast, the initial frequency drift manifests as
intermittent picture break-up until the system stabilises. *The solution, no
doubt, is to obtain a suitably specified LNB...

May I ask why/how you are switching between four LNBS? Four dishes?

John

On 21 Apr, 22:03, "Graham." wrote:
The system will have to feed my apartment to start with, with the
maximum need to feed up to 115 flats and apartments, some of might
want more than one outlet e.g. for a TVs in the living room and
bedroom etc.

Still wondering what those different types of LNB do!



John, I am no expert on Sat distribution systems, but this worries me on at least two
fronts.
Firstly, who put this constraint in place that the satellite "head end" should be in
yours, or anyone else's flat? Was it you, or your contractor?

The dishes would be on the roof and any associated equipment would be
in the water tank room which is in a very large room also on the roof.

Therefore, I think, that the 'headend' would not be in my apartment.
The only thing in my apartment would be cabling and a small box that
converts the laser signal back into a signal that a decoder can use
(rf, I guess).



This is most unusual. Where is the existing aerial distribution point? Surely that
is where the additional kit should be.

On the roof and yes.

Not quite sure why you think it would be elsewhere!


Presumably additional cables are going to be run to the individual flats from here.
That will constitute the bulk of the work involved.

Indeed.


I have read about these optical LNBs they are quite new and very possibly the
way forward for the future, but right now this kit is very specialised, very
expensive and hardly anyone has any experience of using it.

The firm that I have spoken to and used in the past has experience of
it from the St Pancras International railway station development.


If the fibre needs to be spliced and terminated then its even more specialised.

No idea about that! Sorry!


Add to that the fact the outdoor bit (the LNB itself) will be exposed to our British
climate.

As with all LNBs, traditional or otherwise, I suppose!

I just hope that the dishes do not need replacing after every winter
as the winds up at roof level are many miles per hour worse than at
pavement level.


Will it be so difficult to run 4 conventional co-ax cables?

Probably not, though four cables would probably then need the hiring
of somebody to drill through each and every concrete floor in the
risers, whereas I hope that with fibre optic cable, only one cable
will be required.

I was told each floor drilling would cost £50 each or thereabouts!


Blocks such as yours are routinely installed with a conventional Quatro and cables.

I will be interested to hear Bill's thoughts on this.

Indeed.

John

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember John saying
something like:

This is most unusual. Where is the existing aerial distribution point? Surely that
is where the additional kit should be.

On the roof and yes.

Not quite sure why you think it would be elsewhere!

Because that's what it read like.

"At long last, after many, many years of planning and saving, I am,
hopefully, going to have a couple of satellite dishes stuck on the top
of the tower block where I live (planning permission expected) and fed
down to my apartment. Access to the signals will then be available to
others in the block to help me to recover the capital cost of
installation."

"John" wrote:
On 21 Apr, 16:27, "John Legon" wrote:

Well, if you're switching between four LNBs as I am, only one LNB
receives
power at a given time, leaving the others to go cold so to speak. This
doesn't matter at all for DVB-S HD and SD signals, but when switching to
an LNB for a DVB-S2 HD broadcast, the initial frequency drift manifests
as
intermittent picture break-up until the system stabilises. The solution,
no
doubt, is to obtain a suitably specified LNB...

May I ask why/how you are switching between four LNBS? Four dishes?

Three LNBs on one dish for reception of Astra 28E, Astra 19E and Hotbird
13E, and one LNB on a second dish for anything I care to point it at -
currently Eurobird 9E. Switching is automatic through a four-way DiSEqC
switch.

FWIW, the second dish is connected to the switch through a 25-metre run of
cheap satellite cable - the thinly braided stuff that the experts say should
never be used. Another length of ten metres or so goes to the first
receiver, from the loop-through of which a run of about 20 metres goes to
the second receiver. So that's more than 50 metres of cable, despite which
the signal quality at the second receiver is from 60% to 80% (depending on
transponder).