Petition to stop FM being switched off

Fredxx wrote:
"Dave Higton" wrote in message
...
In message en.co.uk
Roderick Stewart
wrote:

In article , Dave Higton wrote:
I /do/ understand the technologies involved. FM is worse than DAB
because all the decoders we use are non-linear, therefore FM
broadcasts, once received, are subject to intermodulation and
harmonic distortions. DAB isn't. It is very much like the vinyl
versus CD and valves versus transistors arguments.
My apologies for repeating myself, but this silly argument seems to
have been repeated a few times and needs nailing down.

Saying that a comparison between FM and DAB is like a comparison
between vinyl and CD is nuts. DAB uses destructive digital bit-rate
reduction; CD doesn't. CD audio is sampled at more than twice the
highest frequency most people can hear, with enough bits to give a
dynamic range greater than any mechanical gramophone system and
certainly well beyond that of a typical living room, and then no
information is thrown away. None at all. It's better than FM, better
than gramophone records, better than tape cassetes, and it stays that
way all the way to the customer.

The main criticisam of DAB is that information *is* thrown away in such
a manner that it can never be completely recovered, not even
theoretically, and this is done by the broadcasters themselves before
the signal even gets to the transmitter.
Yes, it's thrown away. But it doesn't necessarily result in a
reduction of quality, which is all down to perception.

You appear to be avoiding my point that FM, being analogue and
being demodulated by a system that is non-linear, inevitably
introduces non-linear distortions: intermodulation and harmonic
distortion, to the audio. The DAB system can be engineered so
that the non-linearities are arbitrarily small, perhaps just a
few parts per million.


The point is that analogue systems are generally very linear by design, even
if individual components aren't.

Not really. We are lucky that we have one relatively linear component -
the resistor, and by using feedback with THOSE we can achieve pretty low
distortion set-ups from VERY badly distorting components..transistors
and FETS.



The major distortion as such is that the
bandwidth may not be perfectly flat,

That is not a distortion.

And its pretty possible to build an amplifier flat from DC to well over
100Khz.

In the video game, flat to 50Mhz is on the cards, but the power is not
as high. A few watts, not a few hundred.


but our ears are fairly tolerant to
such errors.

Indeed. What our ears really do NOT like is high order harmonics and
intermodulation products. The harmonics we hear as 'edginess' and the
intermodulation we hear as lack of clarity or muddiness.

Don't forget that our ears aren't entirely linear!

DAB on the other hand has an alarmingly low bit rate. The consequence is
where the decoded signal doesn't follow the original.


Precisely. There is nothing intrinsically wrong with the digits: the
implementation is just crap, thats all.

In article ,
Steve Terry wrote:

"Ato_Zee" wrote in message
...

On 27-Jun-2009, "Steve Terry" wrote:

Fibre will come, but to roll it out to every home and premises is an
order
of magnitude or two more expensive than sticking DSLAMS in the
exchanges.

But if Ian Vallance had started a rolling program of FTC instead
of being more interested in his golf and pension, BT would have
about 80% UK coverage with fibre by now, and with their
monopoly on the ducts (rather than have to dig them) BT
would be the only game in town.
A missed opportunity.
Now they are facing rising competition with an ageing
copper network.
And he got a knighthood !!!!!
It's the most classic an example of the Peter Principle that
I've ever seen.


Wasn't it Vallance who said in 2000 that Broadband was for nerds
and there wasn't and wouldn't be any demand for it from the public?

Right up there with Bill Gates, no need for base memory of more than 640k


and a certain astronomer royal who said that 5 computers would be enough
for the country

--
From KT24

Using a RISC OS computer running v5.11

On Wed, 01 Jul 2009 02:18:23 +0100, The Natural Philosopher
wrote:

Mark wrote:
On Sat, 27 Jun 2009 10:16:56 +0100, The Natural Philosopher
wrote:

Dave Higton wrote:
In message en.co.uk
Roderick Stewart wrote:

The main criticisam of DAB is that information *is* thrown away in such
a manner that it can never be completely recovered, not even
theoretically, and this is done by the broadcasters themselves before
the signal even gets to the transmitter.
Absolutely. What's removed is the stuff you can't hear anyway.

No, that's not true.

You can hear the results of highly compressed audio as you can see the
effects of highly compressed video.

But the question remains as to why they do DESTRUCTIVE compression when
actually they don't need to do it if they use a little bit MORE bandwidth.

Because modern society values quantity over quality so they cram in as
many low bitrate channels as possible.

As I said earlier, the only thing you cant compress non destructively is
full power white noise. Remarkably similar to applause as it happens..;-)

True. Truly random data cannot be compressed without loss. I guess
that's why applause sounds particularly bad on DAB.

Digitisation of analogue signals will always leave some information
'lost' in the form of quantization errors.


No, because the sound itself is quantized anyway. Its molecules of air,
with brownian motion., hitting your ear drums and the rest of the hairs
inside your ears.

It's still an area where information is lost.

--
(\__/) M.
(='.'=) Owing to the amount of spam posted via googlegroups and
(")_(") their inaction to the problem. I am blocking most articles
posted from there. If you wish your postings to be seen by
everyone you will need use a different method of posting.

"The Natural Philosopher" wrote in message
...
Fredxx wrote:
"Dave Higton" wrote in message
...
In message en.co.uk
Roderick Stewart
wrote:



The point is that analogue systems are generally very linear by design,
even if individual components aren't.

Not really. We are lucky that we have one relatively linear component -
the resistor, and by using feedback with THOSE we can achieve pretty low
distortion set-ups from VERY badly distorting components..transistors and
FETS.


I was thinking of demodualtors, which don't rely upon resisitors to give a
linear response. It's normally inherent in their transfer characteristic.



The major distortion as such is that the bandwidth may not be perfectly
flat,

That is not a distortion.

Anything where the output does not follow an input IS a distortion. That
includes frequency response. See http://en.wikipedia.org/wiki/Distortion


And its pretty possible to build an amplifier flat from DC to well over
100Khz.

In the video game, flat to 50Mhz is on the cards, but the power is not as
high. A few watts, not a few hundred.

Video does not demand the same dynamic range as audio.


but our ears are fairly tolerant to
such errors.

Indeed. What our ears really do NOT like is high order harmonics and
intermodulation products. The harmonics we hear as 'edginess' and the
intermodulation we hear as lack of clarity or muddiness.

Don't forget that our ears aren't entirely linear!

DAB on the other hand has an alarmingly low bit rate. The consequence is
where the decoded signal doesn't follow the original.


Precisely. There is nothing intrinsically wrong with the digits: the
implementation is just crap, thats all.


Agreed. And the idea of having 2 different DAB systems!

On Wed, 01 Jul 2009 11:16:08 +0100, Mark wrote:

It's still an area where information is lost.

Lost in the noise...
It's time that fallacy was debunked, yet again...

When digital is done properly (which it mostly has been for many years
now) it really truly is no worse than analogue audio with the same S/N
ratio and bandwidth.

--
Anahata
==//== 01638 720444
http://www.treewind.co.uk ==//== http://www.myspace.com/maryanahata

"neverwas" writes:

Tush! I wouldn't expect anything better from a country which has a head
of government who studied physics, has a doctorate in quantum chemistry
and worked as a researcher. Now we are blessed with a beloved leader
whose doctoral thesis was "The Labour Party and Political Change in
Scotland 1918-29" and so is much better equipped to lead such things.

Did we do any better with a Prime Minister who had degrees in chemistry
and had previously worked as a researcher?

On Wed, 01 Jul 2009 05:56:58 -0500, anahata
wrote:

On Wed, 01 Jul 2009 11:16:08 +0100, Mark wrote:

It's still an area where information is lost.

Lost in the noise...
It's time that fallacy was debunked, yet again...

So you deny the existence of quantisation noise?

When digital is done properly (which it mostly has been for many years
now) it really truly is no worse than analogue audio with the same S/N
ratio and bandwidth.

That's beside the point.

--
(\__/) M.
(='.'=) Owing to the amount of spam posted via googlegroups and
(")_(") their inaction to the problem. I am blocking most articles
posted from there. If you wish your postings to be seen by
everyone you will need use a different method of posting.

On Wed, 01 Jul 2009 13:51:46 +0100, Mark wrote:

So you deny the existence of quantisation noise?

No, but it's only noise.
Analog systems also have noise, so they "lose information" too.

--
Anahata
==//== 01638 720444
http://www.treewind.co.uk ==//== http://www.myspace.com/maryanahata

"Graham Murray" wrote in message
...
"neverwas" writes:

Tush! I wouldn't expect anything better from a country which has a head
of government who studied physics, has a doctorate in quantum chemistry
and worked as a researcher. Now we are blessed with a beloved leader
whose doctoral thesis was "The Labour Party and Political Change in
Scotland 1918-29" and so is much better equipped to lead such things.

Did we do any better with a Prime Minister who had degrees in chemistry
and had previously worked as a researcher?

But she saw the error in her ways, gave up science to do a degree in law.
After all law is far easier and better paid than either science or
engineering!

On Wed, 01 Jul 2009 08:19:25 -0500, anahata wrote:

Analog systems also have noise, so they "lose information" too.

Surely no information is lost, it's just that noise is gained. The trick is to
keep that additional noise to such a low level that it's effect is
insignificant.
--
Alan White
Mozilla Firefox and Forte Agent.
Twenty-eight miles NW of Glasgow, overlooking Lochs Long and Goil in Argyll, Scotland.
Webcam and weather:- http://windycroft.gt-britain.co.uk/weather