I'm sick of freeview not coping with interference

In article ,


[Snip]

Being located 10 miles from Crystal Palace doesn't in itself guarantee
a good picture. Within a radius of 10 miles there are actually 19
(nineteen) relay stations built to serve areas where viewers cannot
receive a satisfactory analogue signal from CP. These relays currently
do not have digital transmissions at all.

and I also remember when Ceefax was first demonstrated at IBC in Grosvenor
House, Park Lane, that the receiver needed 24dB of attenuation in the
aerial feed, despite a full 100m of downlead being used.

Could your Freeview signals be on the brink of overload and the
interference just "breaks the camel's back" ?

--
From KT24

Using a RISC OS computer running v5.11

In article ,
Clint Sharp wrote:
My experience is that even with a fully sorted aerial , DVB-T is
dreadful to watch in the presence of local electrical interference.

Analogue just soldiers on, albeit with some picture noise but, as the OP
said, still very watchable.

As has been pointed out you'd need to experience 'DVB-T' at full power to
make any meaningful comparison.

--
*If one synchronized swimmer drowns, do the rest have to drown too?

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

In article ,
wrote:
On Sun, 01 Nov 2009 13:24:20 +0000 (GMT)
"Dave Plowman (News)" wrote:
Christ you're a ****ing moron , why not **** off back under your
bridge and only reply if you have something worthwhile to say.

Interesting you're now such an expert on interference but haven't a clue
about how to deal with it.

Give me your great insight then. Having today found out our neighbour is
having the same problem perhaps you're going to suggest his antenna and
cable are **** too?

Quite likely given the same firms often cover the same area. And their
qualifications consist of being able to drive a van and climb a ladder.
Count the number of circular FM aerials if you don't believe me.


Snow on an analogue picture is random noise caused by a poor signal.

You seriously believe thats the only possible cause of snow? That rather
explains everything.

Must be the wrong type of snow.

Get a decent pro in to measure your signal strength, since you've
obviously not acted on any of the advice you've been given here.

B2003

--
*A woman drove me to drink and I didn't have the decency to thank her

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

On Mon, 02 Nov 2009 00:24:16 +0000 (GMT)
"Dave Plowman (News)" wrote:
Interesting you're now such an expert on interference but haven't a clue
about how to deal with it.

Give me your great insight then. Having today found out our neighbour is
having the same problem perhaps you're going to suggest his antenna and
cable are **** too?

Quite likely given the same firms often cover the same area. And their
qualifications consist of being able to drive a van and climb a ladder.
Count the number of circular FM aerials if you don't believe me.

Stop digging that hole before you hit the water table and drown.

Actually , on 2nd thoughts ...

B2003

In article ,
wrote:
Quite likely given the same firms often cover the same area. And their
qualifications consist of being able to drive a van and climb a ladder.
Count the number of circular FM aerials if you don't believe me.

Stop digging that hole before you hit the water table and drown.

Thanks for proving you know nothing about aerial installation. Which can
be added to a very long list.

--
*Reality? Is that where the pizza delivery guy comes from?

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

wrote:
On Sun, 1 Nov 2009 09:51:38 +0000
Clint Sharp wrote:
Analogue just soldiers on, albeit with some picture noise but, as the OP
said, still very watchable.

Quite. But for some reason some people on here refuse to believe it. Must
be a herd mentality head in the sand scenario again.

B2003


IMO the main point of DVB-T+MPEG2 is not to upgrade our TV system for
the users, it is to make better use of our resources (ie RF spectrum).
It is a more tightly engineered system that transmits more information
than the analogue system and that means it is more dependant on the
integrity of the medium. People will accept really rubbish analogue
pictures with loads of noise or even the odd line or colour missing, but
on DTV if you get a large impulse it knocks out a large chunk of the
picture+audio. As everyone says, things will improve with the higher
powers but you will never get away from the information compression.
Analogue TV is more robust than digital because of its lower utilisation
of the RF spectrum (on a channel by channel basis), digital could be
made the same if it was desired, and still yielding an improvement in
efficiency, however from an Engineering point of view it is usually
better to go for the higher performance option for consumer stuff, and
the current choice of transmission scheme is considered reasonable,
given all the regulations for EMC.

In the past we could get away with a rusted old aerial and coax with
water in it, but now we need to maintain our equipment more often, or
buy longer lasting equipment, install it better etc.

Its a bit like broadband, the old POTS system works fine even when there
are bad connections all over the place, but broadband is not as tolerant
using the same cables.

Back to the car analogy, DVB-T is like a BMW, analogue is like an old
Volvo. The old Volvo trundles along but not very efficiently or
refined, the BMW needs more maintenance as it gets older but is more
agile and efficient when it works.

--
Tony

In message , Mark Carver
writes
wrote:
On Fri, 30 Oct 2009 23:26:12 +0000 (GMT)
"Dave Plowman (News)" wrote:

How many times must you be told that FreeView is running at well under the
ideal power - and will do until analogue is switched off?
So fecking what?? I'm watching it NOW and have problems with it NOW.
I don't care that it'll be better in 2012. Freeview is supposed to be an
analogue replacement NOW.

No !!!! Wrong I'm afraid.

It's still a supplemental 'bonus' service in London, and will remain so
until the analogue services are shut down (April 2012 for you). As
you've been told, once the analogue services are shut down, then that
will allow the DTT services to be broadcast at their intended power,
200kW in the case of Crystal Palace. Only then will coverage match that
presently provided for analogue.


Agreed.

DTT is not yet the status quo, analogue is.

Until DSO it's akin to a software beta version.

You can use it if you like, and have the hardware, but it's not the
final product, and there's no point in complaining until it is.
--
Ian

On Tue, 03 Nov 2009 04:39:08 +0000
John Rumm wrote:
wrote:

Oh put a sock in it Plowman. I want a transmission system which doesn't die
completely under interference conditions that the old analogue system coped
perfectly well with.

Well by your own admission the analogue system is not coping *perfectly*
well either - you say you can see interference there as well. (I fully
accept that the effects of this particular type of interference may be
less objectionable on analogue).

Its not a case of less objectionable - the difference is watching a
picture with some interference on analogue or a blank screen on digital.

is "different". Impulse noise that may have just give a brief speckle
pattern on the screen under analogue, might stall a digital stream for a
moment. The latter is obviously more objectionable. However the reverse

Ultimately it depends on what digital system you use. Compressed streams
are more susceptable because various parts of the stream are interdependent,
bugger up one bit and a load of other stuff has to be binned. But something
like a simple wav audio stream is almost as resistant to stalling as analogue
since if you mess up some of the data you get a click or buzz in the output but
the decoder carries on regardless.

can also be true, multipath reception that can make analogue unwatchable
will often have no effect on digital.

Ghosting as annoying , but IMO it doesn't make it unwatchable.

B2003

On Tue, 3 Nov 2009 09:39:42 +0000
Ian wrote:
DTT is not yet the status quo, analogue is.

So why have analogue viewers had to put up with their picture being chopped
to 14:9 then for the last few years for most channels and programs if
analogue is still the main broadcast system?

B2003

On Tue, 03 Nov 2009 13:33:29 +0000
John Rumm wrote:
Your wav file is probably a straight set of raw samples. Chop out a lump
or introduce significant errors and you will very quickly hear the
result in the reconstituted audio stream. A digital TV stream is

Sure you will, but my point is that those errors wont prevent the other
adjacent good samples being played. They will only effect the samples they
occur on. Also the human brain is much better at filtering out signal from
noise than any computer program yet written which is why analogue is
still watchable even when half the screen is snow.

the whole system collapses. In the case of your system (and your
neighbours) it sounds rather like there is a local source of quite
powerful interference taking the signal so far out of spec that no
amount of protection or coding is going to help. You may need to enlist

This seems to be the case.

the help of someone who has the appropriate test equipment to identify a
likely cause. Various suggestions have been made as to possible causes.
Also look for things like local digital radio transmitters (PMR, Tetra etc).

Its so intermittent that sods law says when he turned up it wouldn't occur.
No doubt some nearby neighbour has some dodgy piece of equipment or souped
up CB radio or something.

Ghosting as annoying , but IMO it doesn't make it unwatchable.

It does when bad enough to prevent the TV from syncing the picture.

True, but you rarely see it that bad.

B2003