Dave Plowman wrote:
In article ,
stuart noble wrote:
So is there ANY chance of good reception from an internal loft aerial? I
have a friend who is reluctant to have an external aerial on her cute
little cottage but gets good reception (apart from C5) with an internal
aerial.

It's possible to get good reception with a set top aerial under some
conditions.

However, wish I had a quid for everyone who says they've got a 'perfect'
picture when it's anything but...

It's quite difficult to get anything in between "as good as it gets"
and no picture at all on digital. If the signal is marginal then you
may get the occasional freeze but not much else, apart from total loss
of picture.

--
Chris Green )

In article , Dave Plowman
writes
In article ,
stuart noble wrote:
So is there ANY chance of good reception from an internal loft aerial? I
have a friend who is reluctant to have an external aerial on her cute
little cottage but gets good reception (apart from C5) with an internal
aerial.

It's possible to get good reception with a set top aerial under some
conditions.

However, wish I had a quid for everyone who says they've got a 'perfect'
picture when it's anything but...


Ah yes Dave. One man's perfeck piccy is another man's....

Especially when you've had the benefit of seeing what the broadcasters
*are* capable of.....
--
Tony Sayer

In article , Jonathan Peters
writes
On 6 Jan 2004 11:03:16 GMT, wrote:

In uk.d-i-y, Jonathan Peters wrote:

I was trying to do this the cheapest way possible as I don't watch a
huge amount of TV.

Me too: along with not wanting to put money into Rupert Murdoch's pocket.

Good point. The only Rupert I want in my house is the one with checked
trousers.

Well I agree with that sentiment up to a point, but these an awful lot
of the country yet to be covered by digital TV especially those out of
the way locations not served by the main stations.

And in these locations satellite delivery is the only other viable
alternative...

--
Tony Sayer

On Tue, 6 Jan 2004 08:37:34 -0000, "stuart noble"
wrote:



So is there ANY chance of good reception from an internal loft aerial? I
have a friend who is reluctant to have an external aerial on her cute little
cottage but gets good reception (apart from C5) with an internal aerial.

Yes. I use a loft aerial and amp setup to feed 3 TVs and a freeview
box.

--
Niall

In article ,
tony sayer wrote:
Especially when you've had the benefit of seeing what the broadcasters
*are* capable of.....

It's not that long ago that post production - editing and dubbing - caused
pretty severe degradation of the studio stuff - even before the average
domestic telly got to work. But since DigiBeta arrived, and the better
digital dubbing systems, if things are well done the difference is near
undetectable. And there are some very good TV sets around these days too,
as well as plenty of dross.

--
*Half the people in the world are below average.

Dave Plowman London SW 12
RIP Acorn

Niall wrote in message ...
On Tue, 6 Jan 2004 08:37:34 -0000, "stuart noble"
wrote:



So is there ANY chance of good reception from an internal loft aerial? I
have a friend who is reluctant to have an external aerial on her cute
little
cottage but gets good reception (apart from C5) with an internal aerial.

Yes. I use a loft aerial and amp setup to feed 3 TVs and a freeview
box.
That's encouraging. I wonder if the "51 element" aerial Chris refers to
could be connected to the original cable, or would it need new cable?

That's encouraging. I wonder if the "51 element" aerial Chris refers
to could be connected to the original cable, or would it need new
cable?

It is a very good idea to replace the nasty old cheap brown co-ax with
decent low loss cable.

Christian.

In article ,
stuart noble writes

Niall wrote in message ...
On Tue, 6 Jan 2004 08:37:34 -0000, "stuart noble"
wrote:



So is there ANY chance of good reception from an internal loft aerial? I
have a friend who is reluctant to have an external aerial on her cute
little
cottage but gets good reception (apart from C5) with an internal aerial.

Yes. I use a loft aerial and amp setup to feed 3 TVs and a freeview
box.
That's encouraging. I wonder if the "51 element" aerial Chris refers to
could be connected to the original cable, or would it need new cable?



FWIW you could stack your loft full of aerials as long as their
correctly connected and spaced etc. But the cable I would deffo
recommend you upgrade. The new CT100 is far better than the older types
of so called Low Loss aerial cable.....
--
Tony Sayer

Fraser wrote:
"Jonathan Peters" wrote in message
...

My original idea was to buy one of the boxes from Argos and see if it
worked; I could then take it back for a refund if it didn't.
Unfortunately, these items are excluded from Argos' 15-day money-back
guarantee, which leaves me kinda stuck.

I was under the impression that Argos had to follow standard legal
limits for a catalogue shop, which means a 28-day return policy. Most
try to "sell" this as a feature of their shop, but the fact is that
they legally have to.

What gives you that idea?

There are distance selling regulations for goods bought by mail order,
so you'd be able to return a freeview receiver in that case, however
just because Argos are a catalogue shop it doesn't mean you can't
inspect the goods before you buy (they even have a name for it -
"customer view")


The idea is that you don't know what the goods are like until you get
them home, as the shop doesn't have the facilities to show them to
you.

I'd double-check this before putting any money down though!!

I'd hope anyone would, because you're wrong.

IMM wrote:
"Tony Bryer" wrote in message
...
In article ,
Fraser wrote:
I was under the impression that Argos had to follow standard
legal limits for a catalogue shop, which means a 28-day return
policy. Most try to "sell" this as a feature of their shop, but
the fact is that they legally have to.

If the goods aren't faulty then if you buy over the counter they
are under no legal obligation to accept any returns though many
retailers do so. If you buy by mail order you can return goods
under the Distance Selling Regulations, though the general view
seems that you can only do so if you not have actually used them.

Argos is half way between. You can't inspect the goods, they come
boxed and wrapped and ordered from a catalogue. Initially they came
under the normal mail order laws, I'm not sure what the situation is
now.

Oh but you can inspect the goods and you always have been able to. Just
open your mouth and ask.

Lobster wrote:
Jonathan Peters wrote in message
. ..
My original idea was to buy one of the boxes from Argos and see if it
worked; I could then take it back for a refund if it didn't.
Unfortunately, these items are excluded from Argos' 15-day money-back
guarantee, which leaves me kinda stuck.

Just had a quick shufti on Argos' website and it says:

"Please note that this product is excluded from the Argos 16-Day Money
Back Guarantee. This does not affect your statutory rights"

I'm no expert on consumer law but somebody here will be, and will be
able to tell you what your 'statutory rights' are. Is this one of
those cases where would be legally obliged to take back an item as
'not fit for purpose' if returned in as new condition? Maybe it's
just a meaningless disclaimer which attempts to dissuade punters from
doing what you want to do!

Also - note that the cheapest box, ref 532/0448, is apparently not
covered by the waiver. Maybe an accident, maybe not... but even if
that's not the box you're after, there's nothing to stop you buying
it, testing it, then returning it for an upgrade if it works for you,
or a refund if it doesn't.


Just buy it online or by telephone order, then you're covered by the
distance selling regulations that apply to any retailer. You can then
return it within 7 days for any reason you like.

stuart noble wrote:
tony sayer wrote in message ...
Now there is a school of thought with digital transmission that sez
either it works or doesn't which isn't exactly true there is a
halfway stage with the picture lockup and blocking.
So is there ANY chance of good reception from an internal loft
aerial? I have a friend who is reluctant to have an external aerial
on her cute little cottage but gets good reception (apart from C5)
with an internal aerial.

Depends. I got pretty good reception of all the digital multiplexes with
a wideband Unix 100 aerial in the loft from the Oxford transmitter, and
I'm 30 odd miles away on the Northants/Beds/Bucks border. But now that
same aerial is on the roof pointing at Sandy Heath, only 25 or so miles
away, getting an excellent reception of all the multiplexes (and also
gives good analogue pictures too).

The trick is a good aerial, and good downlead cable (CT100 or better).

The Triax Unix 100 is a monster aerial though, about 7ft long....

wrote in message ...
In uk.d-i-y, Andy Hall wrote:

Do these get firmware updates downloaded by the broadcaster like the
satellite boxes do? You might find that there is a firmware
update.....

Yes, the packaging promises over-the-air firmware updates; but these are
initiated by the decoder mfr begging NTL or whoever runs the terrestrial
digital transmitters (similarly for satellite). There's no user-accessible
port down which I can myself flash the firmware. And the manual claims I'll
know about it when a firmware update is sent - the decider will pop up a
dialogue box which requires Assent from me-the-owner to apply the upgrade.
There's a screen which tells me the version numbers of the various
bits of software currently running. The EchostarUK website assures me at
http://www.echostaruk.co.uk/OAD.html that "information about specific
downloads will appear on this page", suggesting none have been released yet.



I had a number of updates for my grundig freeview box before it died. Hmmm....

stuart noble wrote:

Niall wrote in message ...
On Tue, 6 Jan 2004 08:37:34 -0000, "stuart noble"
wrote:



So is there ANY chance of good reception from an internal loft aerial? I
have a friend who is reluctant to have an external aerial on her cute
little
cottage but gets good reception (apart from C5) with an internal aerial.

Yes. I use a loft aerial and amp setup to feed 3 TVs and a freeview
box.
That's encouraging. I wonder if the "51 element" aerial Chris refers to
could be connected to the original cable, or would it need new cable?

Why not? I simply disconnected the old aerial and connected the new
one. You might improve things a bit by using better cable, it depends
what the existing cable is.

--
Chris Green )

"IMM" wrote
| If the goods aren't faulty then if you buy over the counter they
| are under no legal obligation to accept any returns though many
| retailers do so. If you buy by mail order you can return goods
| under the Distance Selling Regulations, though the general view
| seems that you can only do so if you not have actually used them.
| Argos is half way between. You can't inspect the goods, they come
| boxed and wrapped and ordered from a catalogue. Initially they
| came under the normal mail order laws, I'm not sure what the
| situation is now.

There's nothing to stop you asking for something to be brought out before
you buy it in Argos; a lady was giving a CD/radio an exhaustive going-over
whilst I was in the queue behind her the other day.

Owain

wrote in message ...
Why not? I simply disconnected the old aerial and connected the new
one. You might improve things a bit by using better cable, it depends
what the existing cable is.
At least 15 years old I would think. I think I'll tell this neighbour of
mine to just suck it and see. Try the new aerial, then the new cable, then
shove the whole lot on the roof if it doesn't work.

In article , R W
writes
stuart noble wrote:
tony sayer wrote in message ...
Now there is a school of thought with digital transmission that sez
either it works or doesn't which isn't exactly true there is a
halfway stage with the picture lockup and blocking.
So is there ANY chance of good reception from an internal loft
aerial? I have a friend who is reluctant to have an external aerial
on her cute little cottage but gets good reception (apart from C5)
with an internal aerial.

Depends. I got pretty good reception of all the digital multiplexes with
a wideband Unix 100 aerial in the loft from the Oxford transmitter, and
I'm 30 odd miles away on the Northants/Beds/Bucks border. But now that
same aerial is on the roof pointing at Sandy Heath, only 25 or so miles
away, getting an excellent reception of all the multiplexes (and also
gives good analogue pictures too).


Not too surprising that. Sandy has for some time now been on a high rate
34 odd megabit digital feed from London. Oxford IIRC rebroadcasts the
output from Sutton Coldfield which will degrade a bit.....

The trick is a good aerial, and good downlead cable (CT100 or better).


Good idea!..

The Triax Unix 100 is a monster aerial though, about 7ft long....



--
Tony Sayer

On Wed, 7 Jan 2004 11:41:12 -0000, "Christian McArdle"
wrote:

That's encouraging. I wonder if the "51 element" aerial Chris refers
to could be connected to the original cable, or would it need new
cable?

It is a very good idea to replace the nasty old cheap brown co-ax with
decent low loss cable.


If you need to. If you get 100% signal on all muxes, why bother. I did
replace one length as a precaution, as it wasn't even UHF coax and had
a couple of taped splices in, but only with ordinary TV coax from B&Q.
There was also a dodgy connector which needed replacing.

--
Niall

In article , Niall
wrote:

It is a very good idea to replace the nasty old cheap brown co-ax with
decent low loss cable.

If you need to. If you get 100% signal on all muxes, why bother.

Because the HF loss is greater than decent cable, but mostly because the
screening of ordinary cable is inadequate to keep pulse interference out,
which can lead to breakup.


--
AJL Electronics (G6FGO) Ltd : Satellite and TV aerial systems
http://www.classicmicrocars.co.uk : http://www.ajlelectronics.co.uk

Check this for good reception:

Been working at my Father's house on his TV distribution. The whole
house had been re-wired with co-ax going to every bedroom. Had already
installed a new external aerial and distribution box in the loft over
a year back, but eventhough the main TV had a beautiful picture, with
all analogue and digital channels coming up, the TVs on the
distribution end were grainy. After checking every connection,
faceplate etc found I had been using the distribution cable for the
main tv not the actual aerial. Bloody thing was pulling all channels
on just the co-ax running up the wall.

On Wed, 7 Jan 2004 18:40:11 +0000, "Andy Luckman (AJL Electronics)"
wrote:

In article , Niall
wrote:

It is a very good idea to replace the nasty old cheap brown co-ax with
decent low loss cable.

If you need to. If you get 100% signal on all muxes, why bother.

Because the HF loss is greater than decent cable, but mostly because the
screening of ordinary cable is inadequate to keep pulse interference out,
which can lead to breakup.

So if it happens, change the cable. But freeview *can* work perfectly
well without an enormous aerial array and CT100 all over the place.
If you have a reasonable analogue picture, it will probably work fine.

--
Niall

"Owain" wrote in message
...
"IMM" wrote
| If the goods aren't faulty then if you buy over the counter they
| are under no legal obligation to accept any returns though many
| retailers do so. If you buy by mail order you can return goods
| under the Distance Selling Regulations, though the general view
| seems that you can only do so if you not have actually used them.
| Argos is half way between. You can't inspect the goods, they come
| boxed and wrapped and ordered from a catalogue. Initially they
| came under the normal mail order laws, I'm not sure what the
| situation is now.

There's nothing to stop you asking for something to be brought out before
you buy it in Argos; a lady was giving a CD/radio an exhaustive going-over
whilst I was in the queue behind her the other day.

They don't have too.



---
--

Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.555 / Virus Database: 347 - Release Date: 23/12/2003

In article , tony sayer
writes
In article ,
stuart noble writes

Niall wrote in message ...
On Tue, 6 Jan 2004 08:37:34 -0000, "stuart noble"
wrote:



So is there ANY chance of good reception from an internal loft aerial? I
have a friend who is reluctant to have an external aerial on her cute
little
cottage but gets good reception (apart from C5) with an internal aerial.

Yes. I use a loft aerial and amp setup to feed 3 TVs and a freeview
box.
That's encouraging. I wonder if the "51 element" aerial Chris refers to
could be connected to the original cable, or would it need new cable?



FWIW you could stack your loft full of aerials as long as their
correctly connected and spaced etc. But the cable I would deffo
recommend you upgrade. The new CT100 is far better than the older types
of so called Low Loss aerial cable.....
I solder all my coax plugs/sockets, i.e. push the central core right
through so that it pokes out the bit that plugs into the telly, video
etc. In the loft I split the aerial down lead into two and use a bit of
15 mm copper pipe hammered oval as a shield. Works fine. A bit of
aluminium corrosion between the junction of copper and coax plug is
bad news for reception.
--
Andrew

In article ,
Andrew wrote:
A bit of aluminium corrosion between the junction of copper and coax
plug is bad news for reception.

I wouldn't bet on it at those frequencies.

--
*Can atheists get insurance for acts of God? *

Dave Plowman London SW 12
RIP Acorn

In article , Niall
wrote:


So if it happens, change the cable. But freeview *can* work perfectly
well without an enormous aerial array and CT100 all over the place.
If you have a reasonable analogue picture, it will probably work fine.

Believe whatever makes you happy. I can only give you the benefit of 16
years in the trade and thousands of digital installations carried out.

--
AJL Electronics (G6FGO) Ltd : Satellite and TV aerial systems
http://www.classicmicrocars.co.uk : http://www.ajlelectronics.co.uk

"Andy Luckman (AJL Electronics)" wrote:
In article , Niall
wrote:


So if it happens, change the cable. But freeview *can* work perfectly
well without an enormous aerial array and CT100 all over the place.
If you have a reasonable analogue picture, it will probably work fine.

Believe whatever makes you happy. I can only give you the benefit of 16
years in the trade and thousands of digital installations carried out.

I believe what I see on my television screen and what a number of
other people here have said. If you have good analogue Channel 5
reception then there's a very good chance that you will get digital
FreeView with the same aerial installation. If not then an aerial
upgrade is probably all that's necessary (assuming you haven't got a
super-duper aerial already). Only if you're trying to squeeze the
last few extra dB of signal out of the system is it worth upgrading
the aerial cables and so on.

--
Chris Green )

stuart noble wrote:

wrote in message ...
Why not? I simply disconnected the old aerial and connected the new
one. You might improve things a bit by using better cable, it depends
what the existing cable is.
At least 15 years old I would think. I think I'll tell this neighbour of
mine to just suck it and see. Try the new aerial, then the new cable, then
shove the whole lot on the roof if it doesn't work.

I think that's the best approach, why spend time/money unnecessarily.

--
Chris Green )

In article ,
wrote:

I believe what I see on my television screen and what a number of
other people here have said.

With digital, you will not see the problem until the signal drops below
threshold, when there will be total picture loss after breakup.
Consequently, you can only tell how reliable or not the installation is by
taking measurements with the proper equipment.


If you have good analogue Channel 5
reception then there's a very good chance that you will get digital
FreeView with the same aerial installation.

It may be the case in some areas, but it depends on where the channel
allocations are in the band. In the case of a group A analogue transmitter
and group C/D digital, your theory is obviously incorrect.

If not then an aerial
upgrade is probably all that's necessary (assuming you haven't got a
super-duper aerial already).

You see, you have a little knowledge, but not enough to understand it fully.
I could spend hours boring you with the science, but I don't really think
you would listen then.

Only if you're trying to squeeze the
last few extra dB of signal out of the system is it worth upgrading
the aerial cables and so on.

It has less to do with cable loss than screening pulse interference although
cable tilt will tend to be worse on non spec cable. You will also find that
the gorillas who install cheap cable in new builds often bend it too sharply
or kink it. That gives rise to "suck out" in parts of the spectrum and can
affect "flatness" of the multiplex(es) affected.

--
AJL Electronics (G6FGO) Ltd : Satellite and TV aerial systems
http://www.classicmicrocars.co.uk : http://www.ajlelectronics.co.uk

In article ,
writes
"Andy Luckman (AJL Electronics)" wrote:
In article , Niall
wrote:


So if it happens, change the cable. But freeview *can* work perfectly
well without an enormous aerial array and CT100 all over the place.
If you have a reasonable analogue picture, it will probably work fine.

Believe whatever makes you happy. I can only give you the benefit of 16
years in the trade and thousands of digital installations carried out.

I believe what I see on my television screen and what a number of
other people here have said. If you have good analogue Channel 5
reception then there's a very good chance that you will get digital
FreeView with the same aerial installation. If not then an aerial
upgrade is probably all that's necessary (assuming you haven't got a
super-duper aerial already). Only if you're trying to squeeze the
last few extra dB of signal out of the system is it worth upgrading
the aerial cables and so on.


Not necessarily so that. You can have good analogue reception if say
your local TX is in A group 21-34 but a digital MUX planted up near the
top end of the band say channel 67 like hereabouts off sandy heath then
this is stretching things a tad too much!.

An A group aerial is way, way, down on level at that separation and co-
ax cables fall in efficiency as the frequency increases, and if they are
of the very open loose weave braided types.

Anyway, why is it that people can spend a small fortune on TV's DVD
players Home cinema and the like and yet be so penny pinching when it
comes to a few tens of pounds for an aerial that will give an adequate
signal that will cope with fades and give excellent service over many
years, and thousands of hours of good quality service?.

Having worked in the TV industry at both ends for some years it still
amazes me as to what crappy and poor reception people will put up with
all for the want of a few quid's worth of metal!....
--
Tony Sayer

In article ,
wrote:
I believe what I see on my television screen and what a number of
other people here have said. If you have good analogue Channel 5
reception then there's a very good chance that you will get digital
FreeView with the same aerial installation. If not then an aerial
upgrade is probably all that's necessary (assuming you haven't got a
super-duper aerial already). Only if you're trying to squeeze the
last few extra dB of signal out of the system is it worth upgrading
the aerial cables and so on.

I'm in a strong signal area - close to Crystal Palace in SW London where
there is probably more RF radiated than anywhere else in the country, and
what you've also got to consider is spurious pickup of unwanted signals
via the co-ax - normal UHF stuff is poorly screened.

Also, co-ax can deteriorate with age - I've seen it full of water. ;-)

I use radio mics a lot in my job, and the UHF versions of these are
extremely sensitive to the type of cable used as they work at tiny powers.
And the cable we use for more than very short runs is a great deal larger
and more expensive than anything used domestically.

--
*A conscience is what hurts when all your other parts feel so good *

Dave Plowman London SW 12
RIP Acorn

Andy Luckman (AJL Electronics) wrote:
In article ,
wrote:
If you have good analogue Channel 5
reception then there's a very good chance that you will get digital
FreeView with the same aerial installation.

It may be the case in some areas, but it depends on where the channel
allocations are in the band. In the case of a group A analogue
transmitter and group C/D digital, your theory is obviously incorrect.

All too true. Several years ago (wisely?) put up a good aerial thinking it
would be an idea to have one in the correct band A, rather than a generic
wideband one. Perfect C5, rubbish at Freeview as it's on a different aerial
group. Should have got a semi-wideband K? instead. Mind you, what do people
watch on Freeview? Listening to 5live seems about the only thing worth
having.

--
Toby.

'One day son, all this will be finished'

In article ,
Toby wrote:
Mind you, what do people
watch on Freeview? Listening to 5live seems about the only thing worth
having.

ITV2 has some good repeats - the original Morse series was on recently.
BBC4 has some decent enough stuff too. Of course it depends on your tastes.

It's also probably the best source of radio, audio quality wise, since DAB
rates have been set so low on many stations.

And assuming the programme source is up to it, the picture quality *is*
better in many ways than the very best analogue - provided you feed the
set with RGB. It has a wider luminance bandwidth, so can provide sharper
pictures, and more noise free deep colours. It's not universally better,
though, as some artifacts can be seen on some movement at certain times.

--
*According to my calculations, the problem doesn't exist.

Dave Plowman London SW 12
RIP Acorn

wrote in message ...
Dave Plowman wrote:
In article ,
stuart noble wrote:
So is there ANY chance of good reception from an internal loft aerial? I
have a friend who is reluctant to have an external aerial on her cute
little cottage but gets good reception (apart from C5) with an internal
aerial.

It's possible to get good reception with a set top aerial under some
conditions.

However, wish I had a quid for everyone who says they've got a 'perfect'
picture when it's anything but...

It's quite difficult to get anything in between "as good as it gets"
and no picture at all on digital. If the signal is marginal then you
may get the occasional freeze but not much else, apart from total loss
of picture.

I don't agree. We live within 3 miles of Sandy Heath, which makes it
easy to get an excellent signal, and of course it's easy to mess it up
if you want to experiment...

I've found it's easy to have terrible analogue with near-perfect
digital, excellent analogue with limited digital, and any combination
in between. What's more, it's very easy to get stop-start digital,
mostly glitchy digital, mostly OK digital, or digital which works most
of the time but has a very slight freeze/jump once or twice an hour.

For now, we have a home made experimental log periodic aerial I made
from plastic sheeting and aluminium foil, suspended from two nails in
the loft. It cracked the analogue channel five problem (except in the
middle of summer), but we get occasional jumps on digital BBC1 (not
BBC4 though - strange, given the frequencies at Sandy Heath).

It's a pity this "free" aerial got so close, because it's now hard to
justify the expense of sending a professional up on the roof.

Cheers,
David.

P.S. This question would be more at home in uk.tech.digital-tv where
you will already find many answers!

"Andy Luckman (AJL Electronics)" wrote:
In article ,
wrote:

I believe what I see on my television screen and what a number of
other people here have said.

With digital, you will not see the problem until the signal drops below
threshold, when there will be total picture loss after breakup.
Consequently, you can only tell how reliable or not the installation is by
taking measurements with the proper equipment.

If the picture never breaks up or disappears then the signal is good
enough. It doesn't take measuring equipment to show that.

If you are a business installing an aerial then it's a whole different
ball game as you can't afford to prove the installation is good enough
by watching it for a week in varying weather conditions. So measuring
equipment is then useful, however not nearly so useful/necessary for a
DIYer.



If you have good analogue Channel 5
reception then there's a very good chance that you will get digital
FreeView with the same aerial installation.

It may be the case in some areas, but it depends on where the channel
allocations are in the band. In the case of a group A analogue transmitter
and group C/D digital, your theory is obviously incorrect.

OK, but there are not so many areas where the digital MUXs are
transmitted on frequencies a long way away from the analogue ones, the
frequency planning has tried to minimise that. What I was really
trying to say though was that if you can get a good channel 5 signal
then you probably can get good digital reception with a similar type
of aerial, quite likely in most areas the same aerial.


If not then an aerial
upgrade is probably all that's necessary (assuming you haven't got a
super-duper aerial already).

You see, you have a little knowledge, but not enough to understand it fully.
I could spend hours boring you with the science, but I don't really think
you would listen then.

I have a degree in Electrical Engineering, worked at Marconi
Instruments (who make signal generators) for many years, was a SWL for
many years, etc., etc. I doubt if anyone "understand[s] it fully",
one of the things one learns is that knowing more tends to open your
eyes to how much you don't know.

It's mostly engineering not science in my opinion.


Only if you're trying to squeeze the
last few extra dB of signal out of the system is it worth upgrading
the aerial cables and so on.

It has less to do with cable loss than screening pulse interference although
cable tilt will tend to be worse on non spec cable. You will also find that
the gorillas who install cheap cable in new builds often bend it too sharply
or kink it. That gives rise to "suck out" in parts of the spectrum and can
affect "flatness" of the multiplex(es) affected.

Is interference a serious problem with digital? Not only that but
does cheap cable *really* let in more noise than expensive cable?
Even at the frequencies involved the mesh of 'cheap' cable must be
pretty well impervious to signal getting onto the downlead, does the
extra aluminium foil of more expensive cable really help in reducing
interference pick up or is it much more to do with reducing
attenuation (or is it even more to do with selling soemthing expensive
unnecessarily)?

--
Chris Green

In uk.d-i-y, Dave Plowman wrote:

And assuming the programme source is up to it, the picture quality *is*
better in many ways than the very best analogue - provided you feed the
set with RGB. It has a wider luminance bandwidth, so can provide sharper
pictures, and more noise free deep colours. It's not universally better,
though, as some artifacts can be seen on some movement at certain times.

Nice to hear the tech-nick-ally noll-ijjable confirm what my own
unsystematic A-B comparison suggested. Our TV does take an RGB feed
from the Freeview decoder (passing it hopefully unmangled through the
video recorder's pair-o-scarts: only 2 scarts on the TV with one
dedicated to DVD). What with the better picture, and the more useful
Guide for a greater-depth "now-and-next" listing, we've taken since
having the Freeview box in at the start of the year to watching even
the mainstream channels through the FV box.

Stefek

In article ,
wrote:
Nice to hear the tech-nick-ally noll-ijjable confirm what my own
unsystematic A-B comparison suggested. Our TV does take an RGB feed
from the Freeview decoder (passing it hopefully unmangled through the
video recorder's pair-o-scarts: only 2 scarts on the TV with one
dedicated to DVD).

I'd be most surprised if the VCR looped through RGB. And has your set two
RGB SCARTS?

--
*Verbs HAS to agree with their subjects *

Dave Plowman London SW 12
RIP Acorn

In article , Dave Plowman
writes
In article ,
Toby wrote:
Mind you, what do people
watch on Freeview? Listening to 5live seems about the only thing worth
having.

ITV2 has some good repeats - the original Morse series was on recently.
BBC4 has some decent enough stuff too. Of course it depends on your tastes.

It's also probably the best source of radio, audio quality wise, since DAB
rates have been set so low on many stations.

And assuming the programme source is up to it, the picture quality *is*
better in many ways than the very best analogue - provided you feed the
set with RGB. It has a wider luminance bandwidth, so can provide sharper
pictures, and more noise free deep colours. It's not universally better,
though, as some artifacts can be seen on some movement at certain times.


Do call in if you're up this way (Cambridge) Dave anytime to do an A/B
twixt analogue and digital. But then again is the feed to Crystal Place
all that good these days?....
--
Tony Sayer

In article ,
tony sayer wrote:
Do call in if you're up this way (Cambridge) Dave anytime to do an A/B
twixt analogue and digital. But then again is the feed to Crystal Place
all that good these days?....

Well, at one time it was the source of emergency analogue RBR so I assume
they keep it up to scratch...

Had a distorting limiter some years ago on BBC 1 and nobody at the BBC
would believe me - I can get Hannigton here to and could switch between
them.

--
*The statement below is true.

Dave Plowman London SW 12
RIP Acorn

wrote in message
...

If the picture never breaks up or disappears then the signal is good
enough. It doesn't take measuring equipment to show that.

FSVO "never" (such as "never, ever, ever") perhaps.

If you are a business installing an aerial then it's a whole
different ball game as you can't afford to prove the installation
is good enough by watching it for a week in varying weather
conditions. So measuring equipment is then useful, however not
nearly so useful/necessary for a DIYer.

A couple of points he firstly, many contributors to this thread have said
that they can get DTT reception, despite the postcode database (which does
err slightly on the cautious side) predicting otherwise. Be aware that
signal strength alone is not the only issue. Every UHF channel is re-used
hundreds of times over and coverage is mostly limited by co-channel and
adjacent channel interference from other TV transmitters, rather than by
thermal noise. Now, as many will be aware, UHF propagation is seriously
affected by certain weather conditions which give rise to 'tropospheric
ducting', increasing the signal levels from remote transmitters by large
amounts and causing severe interference[1]. The statistics of this effect
are well-studied and DTT coverage is planned to work for 99% of the time
(c.f. 95% of time for analogue TV). Some of those receiving in areas which
are not officially classed as 'covered' can expect to experience
tropospheric interference for more than 1% of the time.

Secondly, in the absence of any test equipment, a simple test of signal
margin is to insert a 3 dB attenuator pad at the receiver input. If this
leads to reception failure then your signal is somewhat marginal.

OK, but there are not so many areas where the digital MUXs are
transmitted on frequencies a long way away from the analogue ones,

Oh yes there a look at Belmont, Sandy Heath, Wenvoe and Waltham, to pick
four examples of main transmitters which have some of the mux's well outside
the original analogue group.

the frequency planning has tried to minimise that.

And has concentrated on population served: thus Crystal Palace, Sutton
Coldfield and Winter Hill get more-or-less in-group DTT channel allocations,
but for the rest of the country it's much more patchy.

What I was really trying to say though was that if you can get a
good channel 5 signal then you probably can get good digital
reception with a similar type of aerial, quite likely in most areas
the same aerial.

I think you're just introducing a red herring in suggsting that DTT
reception will be correlated with analogue C5 (which is not even radiated
from many TX sites). In any case very few people upgraded their aerials for
C5, so the existing one will most likely match the original 4-channel plan
group.

Is interference a serious problem with digital? Not only that but
does cheap cable *really* let in more noise than expensive cable?
Even at the frequencies involved the mesh of 'cheap' cable must be
pretty well impervious to signal getting onto the downlead, does the
extra aluminium foil of more expensive cable really help in reducing
interference pick up or is it much more to do with reducing
attenuation (or is it even more to do with selling soemthing
expensive unnecessarily)?

No, it's not a con. What Andy L was talking about there is 'impulsive
interference' - interference from sparking contacts - to which DTT is quite
sensitive. Impulses propagate on, and are radiated from, mains wiring, and
thus are much stronger in the house and loft than above the roof (which
provides some screening). A well-screened coax downlead from antenna to
receiver will largely prevent impulses entering the signal path. With poor
screening, a coupling mechanism exits to allow impulse energy into the
receiver, resulting in the familiar momentary 'freezes' and clicks.

Using well screened coax is necessary, but not sufficient. Any gaps in the
screening will allow the interference to get in, and poorly screened outlet
plates and flyleads are the other betes noir. At the other end of the coax,
the lack of a balun on the aerial will also provide a coupling mechnanism.
This is all sound theory, and has been verified experimentally in tests done
under controlled conditions. Oh, and an aerial in the loft is likely to be
close to mains wiring, so is asking for trouble.

With a really well-screened system and a decent receiver you can get solid
reception with signal levels down to 35 dBuV, even on the 64-QAM muxes
(ITV/C4 and SDN). With grotty brown open-weave coax and a typical outlet
and flylead, you may need 45 or even 50 dBuV before the signal is strong
enough to swamp the impulse interference.


[1] http://www.bbc.co.uk/reception/facts...on_weather.pdf

Also relevant:
http://www.dtg.org.uk/publications/books/r_book2.pdf
http://www.dtg.org.uk/publications/b...rk_aerials.pdf

--
Andy

In uk.d-i-y, Dave Plowman wrote:

I'd be most surprised if the VCR looped through RGB. And has your set two
RGB SCARTS?

Not sure about the first, as the VCR (very recently bought Panasonic) has
naff-all documentation. It's vaguely plausible that it does, as I've told
the Freeview box to push out RGB rather than composite video, and there's
a signal visible on the TV; however it's also possible that the menu lies
and the RGB is an "also" rather than an "either".

As for the second (pops downstairs to retrieve the TV's Book Of Words...)
well, it seems that the set (also a Panasonic) does not have two RGB Scarts.
The first one, to which the VCR and transitively the Freeview box connect,
is RGB-capable. The second is not RGB-capable, but is S-Video capable, so
I *think* the DVD player is sending a plausibly-decent signal to the TV
through that route. It's possible there could be some marginal benefit
from swapping these two inputs round, with the DVD player going to the
RGB-capable one and the VCR to the other one; but then I might get a
less good signal from the Freeview box, which has to feed into the VCR for
recordability. Ah, choices, choices... and it'll get more funky still if
I do revive the satellite receiver!

One can't help concluding there's a tension between providing minimal-cost
caters-for-most-cases-adequately connectivity which doesn't confuse the
consumer population at large, and providing flexibility and a high-quality
signal path for a variety of devices (well duh!). SCART connections seem to
have acquired quite a few bits of added-on Flexibility, stretching the pin
assignments beyond the initial design with its simplistic "look at me! I've
asserted +5V on the look-at-me line, so look at me!" idea... but I don't see
anything else (Firewire/mLAN?) becoming a universal, self-configuring,
self-describing, digital, easy-to-interconnect consumer AV interconnect
standard just yet. Unless (shudders at memory of amusingly-shaped vegetable
and over-prominent teeth) You Know Better?

Stefek