Digital TV for Residential Care Homes
 

This may not be the right place to post this, but it's a start
Am looking into the above as we have a number of residential care homes with
40+ residents in London and the South East and with digital switchover in
the not too distant future, we are looking for a viable solution
I know there are solutions for hotel chains and the like, but is anyone able
to point me in the right direction in terms of where to start looking

Thanks

Nicola

Digital TV for Residential Care Homes
 

"Nicola Redwood" wrote in message
...
This may not be the right place to post this, but it's a start
Am looking into the above as we have a number of residential care homes
with 40+ residents in London and the South East and with digital
switchover in the not too distant future, we are looking for a viable
solution
I know there are solutions for hotel chains and the like, but is anyone
able to point me in the right direction in terms of where to start looking

General advice.

1. In places of that size and type the conversion of the TV system often
requires minimal work (the exception being when the TV system is more than
about 30 years old). Quite often all that's required is a different aerial
and main amplifier. Sometimes not even that. The sensible way to proceed is
often to attend to these items, then check each outlet and deal with any
individual problems.

2. Post-switchover, your existing system would probably work fine as it is
now! The problem is getting to the switchover moment, because until then
digi will be low powered on sometimes on 'awkward' channels.

3. Many installers will see your organisation as a cash cow, and will
recommend totally unneccessary work at every establishment. They will also
try to panic you by saying that if you don't get all the work done now
everyone will be too busy later. This has a grain of truth in it, but is not
sufficient reason to start throwing money about.

4. If you have any old systems that need a complete new installation, put
satellite on them as well as terrestrial. Your next generation of residents
will expect it.

There's a chap on this newsgroup who does good work and is based in the
south east. Let's see if he pops up.

If you're wondering how I know so much, it's because we maintain systems for
quite a few outfits like yours in the north. I don't think there's much on
our website that directly answers your questions but it's wrightsaerials.tv
if you want to have a browse.

Bill

Digital TV for Residential Care Homes
 

"Nicola Redwood" wrote in message
...
This may not be the right place to post this, but it's a start
Am looking into the above as we have a number of residential care homes
with 40+ residents in London and the South East and with digital
switchover in the not too distant future, we are looking for a viable
solution
I know there are solutions for hotel chains and the like, but is anyone
able to point me in the right direction in terms of where to start looking

Thanks

Nicola


I think the solutions will depend on what kind of system each home has in
place and what you want to achieve.

You might find that many of the homes don't need any work doing to the
distribution system, but in these you will need to solve the problem of
residents not having a digital (Freeview) box if they don't have one
already. You could of course make sure they each have their own box, and
that might be the end of it for some of the homes. Where this wouldn't work
though, there are solutions available so they can pick up the 5 channels and
use the TVs as they normally would without needing a digital box for each
resident. They can have extra channels if required or just the same 5 as
they always had.

Many of the homes will probably have a poor distribution system so these
will need additional work to bring them up to scratch. As Bill said though,
this usually just means a new aerial and / or amplifier then some time
picking up any problems with small problems such as sockets / leads etc.

At the other end of the scale there are IPTV systems which use the buildings
structured cabling network. If the building already has an IP network
installed, and the old TV system is beyond repair, then this can be quite a
cost effective solution, especially for much larger buildings.

Digital TV for Residential Care Homes
 

In article ,
Nicola Redwood wrote:
This may not be the right place to post this, but it's a start Am
looking into the above as we have a number of residential care homes
with 40+ residents in London and the South East and with digital
switchover in the not too distant future, we are looking for a viable
solution I know there are solutions for hotel chains and the like, but
is anyone able to point me in the right direction in terms of where to
start looking

In the majority of the London area, assuming your communal aerial works ok
for analogue it will work ok for FreeView. So only the sets themselves
will have to be changed.

--
*If Barbie is so popular, why do you have to buy her friends? *

Dave Plowman London SW
To e-mail, change noise into sound.

Digital TV for Residential Care Homes
 

"Carpy" wrote in message
...
Where this wouldn't work though, there are solutions available so they
can pick up the 5 channels and use the TVs as they normally would without
needing a digital box for each resident. They can have extra channels if
required or just the same 5 as they always had.
I'm really not in favour of this. It's very backwards looking, and it's just
postponing the inevitable and confusing the issue. It isn't such a massive
thing for people to use a set top box, and the few that really can't manage
a second remote need an IDTV. I think that post-ASO we will laugh at the
idea of converting DTT signals into analogue for distribution. When BBC2
started people just had to learn to use the system switch, which was a
bloody sight more difficvult than using a DTT set top box. There was no
question of converting 625 to VHF 405!


Many of the homes will probably have a poor distribution system so these
will need additional work to bring them up to scratch. As Bill said
though, this usually just means a new aerial and / or amplifier then some
time picking up any problems with small problems such as sockets / leads
etc.

At the other end of the scale there are IPTV systems which use the
buildings structured cabling network. If the building already has an IP
network installed, and the old TV system is beyond repair, then this can
be quite a cost effective solution, especially for much larger buildings.
I think 40 bed homes will have conventional copper wired RF for a long time
yet.

Anyway Carpy, give this lady your business card. It sounds as if you could
save her getting ripped of by some of the sharks that infest your southern
waters.

Bill

Digital TV for Residential Care Homes
 

"Dave Plowman (News)" wrote in message
...
In article ,
Nicola Redwood wrote:
This may not be the right place to post this, but it's a start Am
looking into the above as we have a number of residential care homes
with 40+ residents in London and the South East and with digital
switchover in the not too distant future, we are looking for a viable
solution I know there are solutions for hotel chains and the like, but
is anyone able to point me in the right direction in terms of where to
start looking

In the majority of the London area, assuming your communal aerial works ok
for analogue it will work ok for FreeView. So only the sets themselves
will have to be changed.

Yes, we find that many housing organisations are being railroaded into
unneccessary work. Most of the Emley Moor systems need zero work.

Bill

Digital TV for Residential Care Homes
 

In article ,
Dave Plowman (News) wrote:
In article ,
Nicola Redwood wrote:
This may not be the right place to post this, but it's a start Am
looking into the above as we have a number of residential care homes
with 40+ residents in London and the South East and with digital
switchover in the not too distant future, we are looking for a viable
solution I know there are solutions for hotel chains and the like, but
is anyone able to point me in the right direction in terms of where to
start looking

In the majority of the London area, assuming your communal aerial works ok
for analogue it will work ok for FreeView. So only the sets themselves
will have to be changed.

I'd disagree with that statement for 2 possible reasons.
1. The distribution system might have channel pass filters.
2. The system might be using 'translated' channels .
neither of these types of system would carry digital signals.

--
From KT24 - in "Leafy Surrey"

Using a RISC OS computer running v5.11

Digital TV for Residential Care Homes
 

"Bill Wright" wrote in message
...

"Carpy" wrote in message
...
Where this wouldn't work though, there are solutions available so they
can pick up the 5 channels and use the TVs as they normally would without
needing a digital box for each resident. They can have extra channels if
required or just the same 5 as they always had.
I'm really not in favour of this. It's very backwards looking, and it's
just postponing the inevitable and confusing the issue. It isn't such a
massive thing for people to use a set top box, and the few that really
can't manage a second remote need an IDTV. I think that post-ASO we will
laugh at the idea of converting DTT signals into analogue for
distribution. When BBC2 started people just had to learn to use the system
switch, which was a bloody sight more difficvult than using a DTT set top
box. There was no question of converting 625 to VHF 405!


Many of the homes will probably have a poor distribution system so these
will need additional work to bring them up to scratch. As Bill said
though, this usually just means a new aerial and / or amplifier then some
time picking up any problems with small problems such as sockets / leads
etc.

At the other end of the scale there are IPTV systems which use the
buildings structured cabling network. If the building already has an IP
network installed, and the old TV system is beyond repair, then this can
be quite a cost effective solution, especially for much larger buildings.
I think 40 bed homes will have conventional copper wired RF for a long
time yet.

Anyway Carpy, give this lady your business card. It sounds as if you could
save her getting ripped of by some of the sharks that infest your southern
waters.

Bill



I agree but as I said it's really only for those who simply couldn't cope
with a digital box / new televsion. I would sometimes spend afternoons
sitting at my nans house trying to convince her to try one of my Freeview
boxes. I tried every possible approach, but she wouldn't hear a word of it.
She simply did not want to entertain the idea and would eventually become
upset if I even mentioned it. I know she would have loved it if she stopped
being so afraid of it but there comes a point where it's best just to let
things lie. She died a few months back aged 92 and with one leg! Tough as
old boots she was!

Digital TV for Residential Care Homes
 

....snip...
In the majority of the London area, assuming your communal aerial works
ok
for analogue it will work ok for FreeView. So only the sets themselves
will have to be changed.

I'd disagree with that statement for 2 possible reasons.
1. The distribution system might have channel pass filters.
2. The system might be using 'translated' channels .
neither of these types of system would carry digital signals.

The simplest way to see is to borrow a Freeview box, talk to a few of the
more helpful residents and plug it in in their room and try. Problem might
be getting them to give the box back afterwards!

Don't forget to mention the radio stations too. Often overlooked but you
never know how many residents might welcome the chance to listen to "Around
the Horn" again.

Paul DS.

Digital TV for Residential Care Homes
 

"Paul D.Smith" wrote in message
...
...snip...
snip
Don't forget to mention the radio stations too. Often overlooked but you
never know how many residents might welcome the chance to listen to
"Around the Horn" again.
Paul DS.

BBC7 my favourite radio channel

Around the Horn.
Bona!

Steve Terry

Digital TV for Residential Care Homes
 

"charles" wrote in message
...
In article ,
Dave Plowman (News) wrote:
In article ,
Nicola Redwood wrote:
This may not be the right place to post this, but it's a start Am
looking into the above as we have a number of residential care homes
with 40+ residents in London and the South East and with digital
switchover in the not too distant future, we are looking for a viable
solution I know there are solutions for hotel chains and the like, but
is anyone able to point me in the right direction in terms of where to
start looking

In the majority of the London area, assuming your communal aerial works
ok
for analogue it will work ok for FreeView. So only the sets themselves
will have to be changed.

I'd disagree with that statement for 2 possible reasons.
1. The distribution system might have channel pass filters.
2. The system might be using 'translated' channels .
neither of these types of system would carry digital signals.

We're talking about little 40 bed places here, so I doubt if many of the
systems will proper input filters, in reality. The most likely 'head-end
will be a Taylor (etc) one in one out amp with enough gain to produce about
48dBmV analogue. They should have filters of course, but . . .
Likewise, they'll only use translated channels as a last resort because of
the cost, so I should think you'd only find them where you can see Crystal
Palace through the upstairs windows, and where it's closer than around ten
miles. Again, this is not as it should be, but there it is.

Bill

Digital TV for Residential Care Homes
 

"Paul D.Smith" wrote in message
...
...snip...
In the majority of the London area, assuming your communal aerial works
ok
for analogue it will work ok for FreeView. So only the sets themselves
will have to be changed.

I'd disagree with that statement for 2 possible reasons.
1. The distribution system might have channel pass filters.
2. The system might be using 'translated' channels .
neither of these types of system would carry digital signals.

The simplest way to see is to borrow a Freeview box, talk to a few of the
more helpful residents and plug it in in their room and try. Problem
might be getting them to give the box back afterwards!

Don't forget to mention the radio stations too. Often overlooked but you
never know how many residents might welcome the chance to listen to
"Around the Horn" again.

If there are CCTV cameras (for the door or carpark) it's a good idea to put
radio with the pictures. Old people appreciate having the local station on
tap without having the fiddle with the radio. It's such a low cost option:
just an £80 tuner from Richer Sounds.

Bill

Digital TV for Residential Care Homes
 

....snip...

Likewise, they'll only use translated channels as a last resort because of
the cost, so I should think you'd only find them where you can see Crystal
Palace through the upstairs windows, and where it's closer than around ten
miles. Again, this is not as it should be, but there it is.

Why is this? Is it because at that distance, "any old bit of wire" will
pick up some signal and you don't want that interfering with the piped
signal which will, of course, be on the same channel?

Paul DS

Digital TV for Residential Care Homes
 

In article ,
Paul D.Smith wrote:
...snip...

Likewise, they'll only use translated channels as a last resort because
of the cost, so I should think you'd only find them where you can see
Crystal Palace through the upstairs windows, and where it's closer
than around ten miles. Again, this is not as it should be, but there
it is.

Why is this? Is it because at that distance, "any old bit of wire" will
pick up some signal and you don't want that interfering with the piped
signal which will, of course, be on the same channel?


exactly so.

--
From KT24 - in "Leafy Surrey"

Using a RISC OS computer running v5.11

Digital TV for Residential Care Homes
 

"Paul D.Smith" wrote in message
...
...snip...

Likewise, they'll only use translated channels as a last resort because
of the cost, so I should think you'd only find them where you can see
Crystal Palace through the upstairs windows, and where it's closer than
around ten miles. Again, this is not as it should be, but there it is.

Why is this? Is it because at that distance, "any old bit of wire" will
pick up some signal and you don't want that interfering with the piped
signal which will, of course, be on the same channel?

Yes. See
http://www.wrightsaerials.tv/resources/pre-echo.pdf
(although it's down right now)

Bill

Digital TV for Residential Care Homes
 

In article ,
charles wrote:
In the majority of the London area, assuming your communal aerial works ok
for analogue it will work ok for FreeView. So only the sets themselves
will have to be changed.

I'd disagree with that statement for 2 possible reasons.
1. The distribution system might have channel pass filters.

In the majority of the London area the FreeView channels would lie within
those pass filters.

2. The system might be using 'translated' channels .

I'd think that unlikely in most care homes. Or not in any of the ones I've
visited. Low cost is usually the aim.

neither of these types of system would carry digital signals.

Of course the obvious thing is to try a FreeView tuner first before
deciding to spend what is likely to be a large amount of money.

--
*Thank you. We're all refreshed and challenged by your unique point of view

Dave Plowman London SW
To e-mail, change noise into sound.

Digital TV for Residential Care Homes
 

"Steve Terry" wrote in message
...
"Paul D.Smith" wrote in message
...
...snip...
snip
Don't forget to mention the radio stations too. Often overlooked but
you never know how many residents might welcome the chance to listen
to
"Around the Horn" again.
Paul DS.

BBC7 my favourite radio channel

Around the Horn.
Bona!

Steve Terry



Sorry Steve, Round the Horn - no A in it!

And what about ISIRTA, Navy Lark, etc etc.

They don't make 'em like that any more!


--
Woody

harrogate three at ntlworld dot com

Digital TV for Residential Care Homes
 

SOT and talking about Richers, anyone see that new cop fly-on-the-wall
series last week?

The scroats drove a 4x4 through the windows of Richers on Vicar Lane in
Leeds, dumped the 4x4 and tried putting large Tvs in the boot of what
looked like a Fiesta or Corsa.

One scroat picked up a 50" TV, slipped on the debris, and fell flat on
his back with the TV on top of him. Could get up, boys in blue felt his
collar. Brilliant!



--
Woody

harrogate three at ntlworld dot com

Digital TV for Residential Care Homes
 

Woody wrote:
One scroat picked up a 50" TV, slipped on the debris, and fell flat on
his back with the TV on top of him. Could get up, boys in blue felt his
collar. Brilliant!


This I've got to see. Was it on BBC by any chance? (iPlayer)

--
Adrian C

Digital TV for Residential Care Homes
 

"Adrian C" wrote in message
...
Woody wrote:
One scroat picked up a 50" TV, slipped on the debris, and fell flat
on his back with the TV on top of him. Could get up, boys in blue
felt his collar. Brilliant!


This I've got to see. Was it on BBC by any chance? (iPlayer)

--
Adrian C



I think it was, either Thursday or Friday and either 20-21h or 21-22h
and it was not far from the end. It was also about Ploice and CCTV which
was where the video came from.. Sorry can't be more exact.

--
Woody

harrogate three at ntlworld dot com

Digital TV for Residential Care Homes
 

"Woody" wrote in message
...
"Steve Terry" wrote in message
...
"Paul D.Smith" wrote in message
...
...snip...
snip
Don't forget to mention the radio stations too. Often overlooked but
you never know how many residents might welcome the chance to listen to
"Around the Horn" again.
Paul DS.

BBC7 my favourite radio channel

Around the Horn.
Bona!

Steve Terry



Sorry Steve, Round the Horn - no A in it!

And what about ISIRTA, Navy Lark, etc etc.

They don't make 'em like that any more!


--
Woody

harrogate three at ntlworld dot com


Sorry, but my Pedant nature kicked in..

It's Round The Horne (note the 'e' at the end..)

The Horne bit comes from Kenneth Horne, one of the shows stars...

Mat (With my friend Ramsden Gnomefumbler... )

Digital TV for Residential Care Homes
 

"Mat C" wrote in message
...


"Woody" wrote in message
...
"Steve Terry" wrote in message
...
"Paul D.Smith" wrote in message
...
...snip...
snip
Don't forget to mention the radio stations too. Often overlooked
but you never know how many residents might welcome the chance to
listen to
"Around the Horn" again.
Paul DS.

BBC7 my favourite radio channel

Around the Horn.
Bona!

Steve Terry



Sorry Steve, Round the Horn - no A in it!

And what about ISIRTA, Navy Lark, etc etc.

They don't make 'em like that any more!


--
Woody

harrogate three at ntlworld dot com


Sorry, but my Pedant nature kicked in..

It's Round The Horne (note the 'e' at the end..)

The Horne bit comes from Kenneth Horne, one of the shows stars...

Mat (With my friend Ramsden Gnomefumbler... )






Don't mind being a pedant, I knew it but that was a typo!


--
Woody

harrogate three at ntlworld dot com

Digital TV for Residential Care Homes
 

Dave Plowman (News) wrote:
In article ,
charles wrote:
In the majority of the London area, assuming your communal aerial works ok
for analogue it will work ok for FreeView. So only the sets themselves
will have to be changed.

I'd disagree with that statement for 2 possible reasons.
1. The distribution system might have channel pass filters.

In the majority of the London area the FreeView channels would lie within
those pass filters.

2. The system might be using 'translated' channels .

I'd think that unlikely in most care homes. Or not in any of the ones I've
visited. Low cost is usually the aim.

neither of these types of system would carry digital signals.

Of course the obvious thing is to try a FreeView tuner first before
deciding to spend what is likely to be a large amount of money.


What about using a passive system, put up a big aerial. You need about
60dBuV digital channel level to feed 64 TV IMO. Don't have to worry
about filters or amplifiers, the result will be a very low noise signal.

STBs and coax are the main expense.
--
Tony

Digital TV for Residential Care Homes
 

"Tony" wrote in message ...
What about using a passive system, put up a big aerial. You need about
60dBuV digital channel level to feed 64 TV IMO. Don't have to worry about
filters or amplifiers, the result will be a very low noise signal.

STBs and coax are the main expense.

Putting up a big aerial has an almost negligible effect on how many times
you can split the signal. But anyway, let's consider your proposition.
0dBmV from the aerial
-2dBmV in the loft
-26dBmV after the 24dB splitter loss
-30dBmV after the downlead loss (that's optimistic unless the flats are only
about a yard wide)
-32dBmV after the outlet and flylead loss.

It ain't gonna work is it?

However, if you were within about five miles of a high powered Tx and if
analogue wasn't to be used (pre-echo issue) then you'd just about get away
with it. It wouldn't be wise though. All it would need would be a dodgy
flylead or a deaf box and you'd get a call out.

In principle though, a star system with all downleads running to a central
point has a lot of advantages. Minimal amplification for a start.

Bill

Digital TV for Residential Care Homes
 

Bill Wright wrote:
"Tony" wrote in message ...
What about using a passive system, put up a big aerial. You need about
60dBuV digital channel level to feed 64 TV IMO. Don't have to worry about
filters or amplifiers, the result will be a very low noise signal.

STBs and coax are the main expense.

Putting up a big aerial has an almost negligible effect on how many times
you can split the signal.

Bill I know who you are, and that you are a knowledgable guy, but this
goes against RF theory, how can you back this up? When I say big aeial
I mean one with more gain.

But anyway, let's consider your proposition.
0dBmV from the aerial
-2dBmV in the loft
-26dBmV after the 24dB splitter loss
-30dBmV after the downlead loss (that's optimistic unless the flats are only
about a yard wide)
-32dBmV after the outlet and flylead loss.


True I did conviently forget some of the losses, especially the coax
losses. I'd revise my figure to 70-80dbuV required at the aerial.

I'm not sure what figures you're working in but -32dBm will easily drive
loads of TVs. A DTV reciever needs about 28dBuV (-80dBm ish) of mux
to get a good picture, more for a stable picture/weather etc (as long as
any adjancent analogue is proportional)

It ain't gonna work is it?

Why not? It does, I have designed several setups for test in labs and
factories for companies I have worked for. All passive distrbution its
all about the level you start with.

However, if you were within about five miles of a high powered Tx and if
analogue wasn't to be used (pre-echo issue) then you'd just about get away
with it. It wouldn't be wise though. All it would need would be a dodgy
flylead or a deaf box and you'd get a call out.


I of course realise it won't work if there isn't enough signal but many
of these places are near transmitters.

I am 10 miles from Divis, looking through a big bunch of Laylandii and
getting about 65-70dBuV at the TV after a 4 split and downlead. I can
dial in 40dB of attentuation before my STB falls over. I am using
43element from Maplin, when normally I can get all DTV (just) on a
settop aerial with direct line of site (up the hill a little). I got a
bit more than I intended actually, but also for STB test purposes.

What are pre-echo issues? I don't see how using a higher gain aerial
can cause any problems atall after you have attentuated/split the
signal. Do higher gains aerial exhibit more echo in the signal? I do
tend to think of digital only these days, we're pretty close to switch off.

In principle though, a star system with all downleads running to a central
point has a lot of advantages. Minimal amplification for a start.


I would describe my system as a tree, but how you split it doesn't
matter. I would have thought placing the 2ndary splitters around the
building will allow less coax than a star. But then I also don't
understand why ethernet networks are built like stars aswell, when local
hubs would significantly reduce the amount of cabling required and do
not reduce bandwidth. Is there some inherant benefit in reliability by
using a star?

--
Tony

Digital TV for Residential Care Homes
 

"Tony" wrote in message ...
Bill Wright wrote:
Putting up a big aerial has an almost negligible effect on how many times
you can split the signal.

Bill I know who you are,
Hell! And you know where I am!

and that you are a knowledgable guy,
Try me with computers . . .

but this goes against RF theory, how can you back this up? When I say big
aeial I mean one with more gain.
Yes, but the difference in gain between, say a ten element aerial and the
biggest high gain aerial on the market is only about 7dB. That amounts to a
three way split. The installation of a big high gain aerial, with all that
implies in terms of appearance, windage, and fixings, is definitely not the
way to acquire an extra 7dB for distribution! If you want to do such a barmy
thing you'd be better with three 10-elements on the roof!


But anyway, let's consider your proposition.
0dBmV from the aerial
-2dBmV in the loft
-26dBmV after the 24dB splitter loss
-30dBmV after the downlead loss (that's optimistic unless the flats are
only about a yard wide)
-32dBmV after the outlet and flylead loss.


True I did conviently forget some of the losses, especially the coax
losses. I'd revise my figure to 70-80dbuV required at the aerial.
Ah. Well, if you can obtain 20dBmV of DTT signal from the aerial I'd be with
you all the way. You'd need to be very close to the tx though! Remember that
the analogue channels would normally be at 40dBmV for this DTT level. I've
seen such signal levels. Four miles from Crystal Palace with clear
line-of-site. 250m from the Crosspool tx on top of a tall building, so
almost level with the tx aerials. But such signal levels are only available
at such locations, very close to high or medium powered transmitters. As
such they are abnormal.


I'm not sure what figures you're working in but -32dBm will easily drive
loads of TVs. A DTV reciever needs about 28dBuV (-80dBm ish) of mux to
get a good picture, more for a stable picture/weather etc (as long as any
adjancent analogue is proportional)
Of course, as every schoolboy knows, the picture is always good on digital
until it isn't. I agree, 'more for a stable picture/weather'. Actually, much
more. The agreed figures have recently been discussed on this newsgroup, and
amount to a safe minimum of around -20dBmV. But for any respectable system
you shouldn't provide less than -10dBmV at the outlet. Think about local
interference from the TV set itself, etc.


It ain't gonna work is it?

Why not? It does, I have designed several setups for test in labs and
factories for companies I have worked for.
When I was ten I designed a machine for squirting water at the neighbour's
baby. Fortunately the mere design completion was not enough to ensure
effective operation of the equipment.

Your systems, I'm sorry to tell you, are a total botch if they provide only
barely adequate levels. You can walk away from a system where every outlet
is giving good reception, but if there's no allowance built in the job is a
botch.

All passive distrbution its
all about the level you start with.
Yes . . . and the losses on the system.


I of course realise it won't work if there isn't enough signal but many of
these places are near transmitters.
To be honest this job isn't just about simple arithmetic. You should never
ever install a system that provides barely adequate levels. In the real
world component values vary, cable losses increase with time, deaf receivers
are common, and ****ty 31p flyleads are sold for £4.50.

Bill

Digital TV for Residential Care Homes
 

On Fri, 25 Jul 2008 01:37:19 +0100, "Bill Wright"
wrote:


"Tony" wrote in message ...
Bill Wright wrote:
Putting up a big aerial has an almost negligible effect on how many times
you can split the signal.

Bill I know who you are,
Hell! And you know where I am!

and that you are a knowledgable guy,
Try me with computers . . .

but this goes against RF theory, how can you back this up? When I say big
aeial I mean one with more gain.
Yes, but the difference in gain between, say a ten element aerial and the
biggest high gain aerial on the market is only about 7dB. That amounts to a
three way split. The installation of a big high gain aerial, with all that
implies in terms of appearance, windage, and fixings, is definitely not the
way to acquire an extra 7dB for distribution! If you want to do such a barmy
thing you'd be better with three 10-elements on the roof!


But anyway, let's consider your proposition.
0dBmV from the aerial
-2dBmV in the loft
-26dBmV after the 24dB splitter loss
-30dBmV after the downlead loss (that's optimistic unless the flats are
only about a yard wide)
-32dBmV after the outlet and flylead loss.


True I did conviently forget some of the losses, especially the coax
losses. I'd revise my figure to 70-80dbuV required at the aerial.
Ah. Well, if you can obtain 20dBmV of DTT signal from the aerial I'd be with
you all the way. You'd need to be very close to the tx though! Remember that
the analogue channels would normally be at 40dBmV for this DTT level. I've
seen such signal levels. Four miles from Crystal Palace with clear
line-of-site. 250m from the Crosspool tx on top of a tall building, so
almost level with the tx aerials. But such signal levels are only available
at such locations, very close to high or medium powered transmitters. As
such they are abnormal.


I'm not sure what figures you're working in but -32dBm will easily drive
loads of TVs. A DTV reciever needs about 28dBuV (-80dBm ish) of mux to
get a good picture, more for a stable picture/weather etc (as long as any
adjancent analogue is proportional)
Of course, as every schoolboy knows, the picture is always good on digital
until it isn't. I agree, 'more for a stable picture/weather'. Actually, much
more. The agreed figures have recently been discussed on this newsgroup, and
amount to a safe minimum of around -20dBmV. But for any respectable system
you shouldn't provide less than -10dBmV at the outlet. Think about local
interference from the TV set itself, etc.


It ain't gonna work is it?

Why not? It does, I have designed several setups for test in labs and
factories for companies I have worked for.
When I was ten I designed a machine for squirting water at the neighbour's
baby. Fortunately the mere design completion was not enough to ensure
effective operation of the equipment.

Your systems, I'm sorry to tell you, are a total botch if they provide only
barely adequate levels. You can walk away from a system where every outlet
is giving good reception, but if there's no allowance built in the job is a
botch.

All passive distrbution its
all about the level you start with.
Yes . . . and the losses on the system.


I of course realise it won't work if there isn't enough signal but many of
these places are near transmitters.
To be honest this job isn't just about simple arithmetic. You should never
ever install a system that provides barely adequate levels. In the real
world component values vary, cable losses increase with time, deaf receivers
are common, and ****ty 31p flyleads are sold for £4.50.

Bill


I did a test with cheap flyleads using my meter, and was surprised at
the difference compared to a short run of CT100. Most flyleads (0.5m)
had up to 2dBuV loss compared to the same length CT100 which, with
DTT, can be the difference between getting a signal and not.

Marky P.

Digital TV for Residential Care Homes
 

In article ,
Marky P wrote:

I did a test with cheap flyleads using my meter, and was surprised at
the difference compared to a short run of CT100. Most flyleads (0.5m)
had up to 2dBuV loss compared to the same length CT100 which, with
DTT, can be the difference between getting a signal and not.

the 'best' one I measured was giving a loss of only a few dBs on ch 39, but
20dB at ch 66!

--
From KT24 - in "Leafy Surrey"

Using a RISC OS computer running v5.11

Digital TV for Residential Care Homes
 

charles wrote:
In article ,
Marky P wrote:

I did a test with cheap flyleads using my meter, and was surprised at
the difference compared to a short run of CT100. Most flyleads (0.5m)
had up to 2dBuV loss compared to the same length CT100 which, with
DTT, can be the difference between getting a signal and not.

the 'best' one I measured was giving a loss of only a few dBs on ch 39, but
20dB at ch 66!


Most accessory fly leads are not shielded at the plug-cable joint, this
results in the large losses. Sheilded plug leads cost typically 30%
more in volume.

--
Tony

Digital TV for Residential Care Homes
 

Bill Wright wrote:
"Tony" wrote in message ...
Bill Wright wrote:
Putting up a big aerial has an almost negligible effect on how many times
you can split the signal.
Bill I know who you are,
Hell! And you know where I am!

and that you are a knowledgable guy,
Try me with computers . . .

but this goes against RF theory, how can you back this up? When I say big
aeial I mean one with more gain.
Yes, but the difference in gain between, say a ten element aerial and the
biggest high gain aerial on the market is only about 7dB. That amounts to a
three way split. The installation of a big high gain aerial, with all that
implies in terms of appearance, windage, and fixings, is definitely not the
way to acquire an extra 7dB for distribution! If you want to do such a barmy
thing you'd be better with three 10-elements on the roof!


Fair enough, to be honest aerials are not my expertise, I am mostly
working with generators/modulators. Maybe my lastest home installation
is just better quality/newer than the one done by Ondigital on my older
house.

I have 2 known locations in the same area, 1 is a 10 element higher up
the hill with no or little obstructions, and is quite marginal in bad
weather and the other is a 43 element behind these trees. The 43
element gets a signal in that is alot more that the difference in aerial
gain. There could be other factors like wet connections/better coax. I
shall be checking it the near future.

Ah. Well, if you can obtain 20dBmV of DTT signal from the aerial I'd be with
you all the way. You'd need to be very close to the tx though!

I'm not familiar with these units and cannot find a converter, they
don't seem to be dBm(W) or dBuV.



Your systems, I'm sorry to tell you, are a total botch if they provide only
barely adequate levels. You can walk away from a system where every outlet
is giving good reception, but if there's no allowance built in the job is a
botch.


I agree a system with barely adequate level would not be robust, indeed
we could not afford the line to be stopped because of a slightly damaged
bit of coax or bad weather.

All passive distrbution its
all about the level you start with.
Yes . . . and the losses on the system.

I of course realise it won't work if there isn't enough signal but many of
these places are near transmitters.
To be honest this job isn't just about simple arithmetic. You should never
ever install a system that provides barely adequate levels. In the real
world component values vary, cable losses increase with time, deaf receivers
are common, and ****ty 31p flyleads are sold for £4.50.


I don't think we dissagree on that, I just thought Aerial gain was the
way to eliminate amplifiers, and still think that it can. But where it
would work is another issue, I don't have the practical experience for
that. I just had the feeling that it is too easily excluded in favour
of expensive amplified system. Heavy duty coax is also another way to
boost levels, often ignored. And the performance of a 20dB distribution
amp is often over estimated, so maybe 7dB of aerial gain is enough.

I have to say, though, that your estimates of required margins are
probably alot more than mine, that is probably representative of our
difference worlds, but that is another debate. While my 80dBuV might be
enough to supply 64 TVs it might not provide enough practical margin to
account for aging/deterioration, but then in my world consumers don't
really care about life time (well not enough to pay extra for it).

--
Tony

Digital TV for Residential Care Homes
 

"Tony" wrote in message ...
Bill Wright wrote:


Ah. Well, if you can obtain 20dBmV of DTT signal from the aerial I'd be
with you all the way. You'd need to be very close to the tx though!

I'm not familiar with these units and cannot find a converter, they don't
seem to be dBm(W) or dBuV.


20dBmV = 80dBuV

Digital TV for Residential Care Homes
 

"Tony" wrote in message ...
Bill Wright wrote:
I don't think we dissagree on that, I just thought Aerial gain was the way
to eliminate amplifiers, and still think that it can.
In some cases it is the right way to go. We look after a large number of
blocks of flats which all have LOS to Emley Moor, which is about 14 miles
away I'd guess. There are 6 flats in each block, and each flat a has a
seperate downlead to the amplifier location. When we took these over (in the
1980s) we found that they all had antique amplifiers which had 26dB gain and
a maximum output across four channels of only around 32dBmV. In front of the
amps were attenuators, usually a fixed 12dB and a variable 0-18dB. Of course
the attenuation almost equalled the amplification! We had a policy of
replacing the aerial and feeder where necessary, replacing the attenuators
and amp with a splitter, and then checking the results. These were always OK
except the wallplate or something was faulty. The improvement in picture
quality was striking. The figures we
+27dBmV at the ae
+23dBmV at the splitter input
+13dBmV at the splitter output
+7 to +10 at the outlet.
Luckily the living rooms mostly faced away from Emley, so pre-echo wasn't a
problem. Those systems are still there, unaltered, and we get very few
problems even with DTT.

There's no doubt that a clean signal off the aerial will beat an amplified
one, if the levels are equal. This is of course because the noise floor is
lower. But the level MUST be much better than adequate at the receivers. If
in doubt turn up the wick!

Bill

Digital TV for Residential Care Homes
 

In message , Carpy
writes

"Tony" wrote in message ...
Bill Wright wrote:


Ah. Well, if you can obtain 20dBmV of DTT signal from the aerial I'd be
with you all the way. You'd need to be very close to the tx though!

I'm not familiar with these units and cannot find a converter, they don't
seem to be dBm(W) or dBuV.


20dBmV = 80dBuV

And, as there's been a couple of dBm used in this thread, 0dBm = 48dBmV
(appx).
--
Ian

Digital TV for Residential Care Homes
 

Ian Jackson wrote:

And, as there's been a couple of dBm used in this thread, 0dBm = 48dBmV
(appx).

pedant
49 is closer. 0 dBm = 48.751 dBmV = 108.751 dBuV in a 75 Ω system.
/pedant

--
Andy

Digital TV for Residential Care Homes
 

In message , Andy Wade
writes
Ian Jackson wrote:

And, as there's been a couple of dBm used in this thread, 0dBm =
48dBmV (appx).

pedant
49 is closer. 0 dBm = 48.751 dBmV = 108.751 dBuV in a 75 0 /pedant

Ah, but I always allowed for 0.751dB loss in the test lead! ;))
--
Ian

Digital TV for Residential Care Homes
 

On Fri, 25 Jul 2008 20:42:13 +0100, Ian Jackson
wrote:

And, as there's been a couple of dBm used in this thread, 0dBm = 48dBmV

As one is power and the other is voltage, it is invalid to compare the two
unless you also specify the impedance.

Digital TV for Residential Care Homes
 

On Thu, 24 Jul 2008 15:36:18 +0100, Tony wrote:

I'm not sure what figures you're working in but -32dBm will easily drive
loads of TVs. A DTV reciever needs about 28dBuV (-80dBm ish) of mux
to get a good picture, more for a stable picture/weather etc

It is pointless quoting signals levels without considering what the noise
level is as well.

Why not? It does, I have designed several setups for test in labs and
factories for companies I have worked for. All passive distrbution its
all about the level you start with.

And what happens when you can't get a high enough level to start with
compared to what you require at the end?

But then I also don't
understand why ethernet networks are built like stars aswell, when local
hubs would significantly reduce the amount of cabling required and do
not reduce bandwidth.

You are clearly a fool if you think local hubs don't reduce bandwidth
available (per branch) on the root.

Digital TV for Residential Care Homes
 

In message , Paul Ratcliffe
writes
On Fri, 25 Jul 2008 20:42:13 +0100, Ian Jackson
wrote:

And, as there's been a couple of dBm used in this thread, 0dBm = 48dBmV

As one is power and the other is voltage, it is invalid to compare the two
unless you also specify the impedance.

TV? TV Aerials? Cable TV? Satellite? Now what impedance would YOU think
we were talking about?
[Clue - it's not 4, 8, 30, 50, 300, 450 or 600 ohms.]
--
Ian

Ethernet (was Digital TV for Residential Care Homes)
 

Tony wrote:

I would describe my system as a tree, but how you split it doesn't
matter. I would have thought placing the 2ndary splitters around the
building will allow less coax than a star. But then I also don't
understand why ethernet networks are built like stars aswell, when local
hubs would significantly reduce the amount of cabling required and do
not reduce bandwidth. Is there some inherant benefit in reliability by
using a star?


I'm assuming you're talking about twisted pair Ethernet, not the
obsolete coax.

It's not about reliability, it's about cost and convenience.

The first thing is that there are fundamentally two kinds of box that
act as the hub of the star. A plain hub takes the signal from each of
the connections, and sends it out on all the other connections. I think
they are getting rare now. The other type, the switch, sends the
messages from each connection to whichever single other port is
required. It might even be sent at a different speed, and the ways in
which the other port is decided varies. Some messages get sent to all
other ports, but not many. A good switch can send messages between
several different pairs of ports simultaneously.

Most networks are designed around a few server computers, which are one
end of most conversations, and a lot of clients which are the other end
of each conversation. You put the servers on high speed links near the
middle of your stars (maybe even several links, which they can use to
spread traffic) and the workstations out near the edges.

If you have a dozen workstations in one room, they can share a hub and a
single long wire back towards the servers. Much less copper.

It's a fundamentally different problem to RF distribution, and one I
wouldn't want to cover in too much detail for fear of running out of
knowledge and making myself look like an idiot!

Andy

Digital TV for Residential Care Homes
 

On Sat, 2 Aug 2008 12:04:56 +0100, Ian Jackson
wrote:

And, as there's been a couple of dBm used in this thread, 0dBm = 48dBmV

As one is power and the other is voltage, it is invalid to compare the two
unless you also specify the impedance.

TV? TV Aerials? Cable TV? Satellite? Now what impedance would YOU think
we were talking about?

33 and a third. Or maybe it's 45.

[Clue - it's not 4, 8, 30, 50, 300, 450 or 600 ohms.]

Take your patronising attitude somewhere else. Oh and you missed out 110.

Things get taken out of context all the time, so it is important to specify
it to prevent a cock-up later.