DAB Performance of different makes?

"DAB sounds worse than FM" wrote:

snip

Damn, that's weird stuff.

And Jim, you really have got the patience of a saint.

--
Dave Farrance

Dave Farrance wrote:
"DAB sounds worse than FM" wrote:

snip

Damn, that's weird stuff.


Not half as weird as when you wrote about modern video codecs being able
to encode using interlacing and progressive at the same time.


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

Please sign the petition asking the BBC to provide better audio quality
on its radio stations on DAB, Freeview, satellite and cable:
http://tinyurl.com/a68e4

"DAB sounds worse than FM" wrote:

Not half as weird as when you wrote about modern video codecs being able
to encode using interlacing and progressive at the same time.

Ah that.

It seemed that half the group were trying to explain to you the meaning
of my post in the simplest step-by-step way that they could conceive,
and I thought you'd almost got it at the end, but evidently not. Ho hum.

Gonna try the "but you said..." thing on ME now? :-)

--
Dave Farrance

On 2005-10-25, Jim Lesurf wrote:
In article , Andrew Hodgkinson
wrote:
Clive Wallis wrote:

Is there much difference in the radio performance between the more
expensive brands, such as Sony & Panasonic, and the cheaper ones, such
as Goodmans, Alba & Bush?

Many digital radios use the same base chipset, or a variant of it. You'd
be surprised how many different makes are based off the same core.

Is there info anywhere on which sets/makers use which chipsets? Or do they
regard this as a dark and shameful secret? ;-

FWIW I've also been interested in seeing if chipsets are available for
'amateur' use as it would be interesting to experiment with them. Anyone
know of a source, etc?
...
Do they also tend to use the same RF frontend? I know that was common in FM
tuners for many years - names like Alps springing to mind from the days of
yore when I was involved in FM tuner design.

There's an IEE Essex region lecture on DAB tonight which I will probably
manage to attend. The abstract says it will include coverage of
"receiver models available". If I do get there I will ask questions
and take notes.

--
John Phillips

Dave Farrance wrote:
"DAB sounds worse than FM" wrote:

Not half as weird as when you wrote about modern video codecs being
able to encode using interlacing and progressive at the same time.

Ah that.

It seemed that half the group were trying to explain to you the
meaning of my post in the simplest step-by-step way that they could
conceive, and I thought you'd almost got it at the end, but evidently
not. Ho hum.


Don't even try to patronise me. YOU GOT IT WRONG FROM THE START.

The fact was that you thought that the new encoders, such as H.264, can
encode some parts of a frame using progressive and some parts of a frame
using interlacing. They can't. I knew that. You were wrong.

Did I need it explaining to me? Damn fking right I did, because you were
explaining something that H.264 COULD NOT DO. I knew it couldn't do it,
so all your explanations were complete nonsense. I could see that, but
nobody else at the time could.

But don't even try and suggest I need things explaining in the simplest
step-by-step way. You were explaining SOMETHING THAT H.264 CANNOT DO.


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

Please sign the petition asking the BBC to provide better audio quality
on its radio stations on DAB, Freeview, satellite and cable:
http://tinyurl.com/a68e4

John Phillips wrote:
On 2005-10-25, Jim Lesurf wrote:
In article , Andrew
Hodgkinson wrote:
Clive Wallis wrote:

Is there much difference in the radio performance between the more
expensive brands, such as Sony & Panasonic, and the cheaper ones,
such as Goodmans, Alba & Bush?

Many digital radios use the same base chipset, or a variant of it.
You'd be surprised how many different makes are based off the same
core.

Is there info anywhere on which sets/makers use which chipsets? Or
do they regard this as a dark and shameful secret? ;-

FWIW I've also been interested in seeing if chipsets are available
for 'amateur' use as it would be interesting to experiment with
them. Anyone know of a source, etc?
...
Do they also tend to use the same RF frontend? I know that was
common in FM tuners for many years - names like Alps springing to
mind from the days of yore when I was involved in FM tuner design.

There's an IEE Essex region lecture on DAB tonight


Who's the lecture being given by?

If they say the system is good, then you'll know that they're talking
nonsense, and the whole of the lecture can be taken with a pinch of
salt.


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

Please sign the petition asking the BBC to provide better audio quality
on its radio stations on DAB, Freeview, satellite and cable:
http://tinyurl.com/a68e4

John Phillips wrote:

There's an IEE Essex region lecture on DAB tonight which I will
probably manage to attend.


Ah, it's by Mike Ellis of BBC R&D. I've seen the slides for the
presentation, because they're available on the BBC R&D website for the
talk he gave at IEE Cambridge. Unfortunately, the slides are so full of
inaccuracies that they're barely worth taking notice of.

After reading Mike Ellis's slides I wrote the following email.
Strangely, he's never replied. My impression of Mike is that he's an RF
man, and isn't well up on digital comms. If he was then he wouldn't have
made the errors that he did -- unless he made the errors on purpose.


Mike,

The amount of spin in your presentation puts politicians to shame.

DAB works very well, does it? No bubbling mud on DAB then?

DAB is 15-times more efficient than FM, is it? I make it that Radios 1-4
are 10 times more efficient on DAB than on FM, actually (think capacity
units, and exclude stations like Radio 5, which only use 9kHz channels
on MW). But local stations are actually less efficient than on FM. I
suppose you didn't want to mention that little unfortunate fact.

"Many people have heard of Reed-Solomon codes, however DAB actually uses
a more powerful code still known as a Convolutional code."

That is either ultra-highly-spun, or you don't actually know what you're
going on about.

Name me one mobile digital communication system that uses Reed-Solomon
coding as its *inner* layer of FEC coding. Just one system.

Everybody worth their salt knows that on mobile digital communation
systems, Reed-Solomon coding is used as the outer layer of FEC coding
around an inner code, such as convoltional coding.

I can even remember talking to you on the phone about Reed-Solomon
coding, and you seemed to understand it then, so why did you try and
mis-represent what it is used for in your presentation?

I'm sure you're well aware of my disdain for the way DAB is marketed in
the UK, but that is nothing compared to how I feel about engineers who
try to mis-represent engineering concepts.


You describe transmitter separation in L-band as being "relatively
large". Really? Do you not mean very small?

"The Proms" on Radio 3 might steal some capacity from Radio 4 to improve
quality?? When has that ever happened?

"decoded signal will be indistinguishable from the
original"????????????????????????????

Coherent modulation gives a (slight) increase in capacity compared to
differential?? Coherent modulation ALLOWS 16-QAM and 64-QAM, I don't
call that a slight increase in capacity.

"DTT doesn't have time interleaving at all! ... but burst errors may
exceed the error correction capability of the Viterbi error correction,
resulting in blocking and/or picture break-up"

So, you thought that you'd say all that, but ignore that DTT does use
Reed-Solomon coding which is used precisely to catch burst errorrs that
result from when the Viterbi error correction fails? I bet in your
presentation you'll have said DVB-H suffers like this, and fail to
mention that it has 2 outer layers of RS coding, including the very
powerful MPE-FEC.

"Most later systems don't offer [UEP] -- all of the data is treated
equally."

Yeah, but DVB-H et al don't use pathetically weak single-layer
convolutional coding.

And in the whole presentation, not a single word about the audio quality
is low.

I have to say that your presentation bears a remarkable resemblance to
many other DAB presentations: lots of spin trying to justify use of an
out-of-date, ultra-inefficient, very high cost system, which virtually
rules out high audio quality, and vastly limits the number of radio
stations that will be made available, thus allowing commercial radio
groups to use protectionist practices, with the overall result that DAB
leads to a vastly inferior system in many respects compared to all the
modern digital broadcasting systems that could be used for radio.

I remember in our last phone conversation that you had the audacity to
say to me (in a tone that seemed to suggest that I should try and
improve things rather than criticise things) that engineering was about
making things better. I suppose the irony that you're supporting the use
of an inherently flawed system, whereas I'm proposing to use modern
systems that totally solve all DAB's flaws hasn't dawned on you?...


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

Please sign the petition asking the BBC to provide better audio quality
on its radio stations on DAB, Freeview, satellite and cable:
http://tinyurl.com/a68e4

Jim Lesurf wrote:
In article , DAB sounds worse
than FM wrote:
[snip]


I don't know how widespread this is, but someone said that albums
released on DVD-Audio aren't compressed to buggery whereas the CD
versions are.


Can't comment on DVD-A. However I recently did an analysis of a Hendrix CD
re-issue with a fancy label. This showed the sounds spent an alarming
fraction of the time within 1dB of clipping. Nothing like the statistics of
any real sounds or older CDs I've analysed in the same way. Looked very
much like being heavily processed for re-issue to give a sound level stuck
at max all the time. This is wandering a bit OT for this group, though...
:-)

Slainte,

Jim


I bought a couple of Hendrix rereleased 'sanctioned by the family' CDs -
sounded terrible, compressed, travesty.

"DAB sounds worse than FM" wrote:

The fact was that you thought that the new encoders, such as H.264, can
encode some parts of a frame using progressive and some parts of a frame
using interlacing. They can't. I knew that. You were wrong.

I thought you wouldn't be able to resist the "but you said" thing ;-)

I think you've half-remembered this:
http://groups.google.com/group/uk.te...9f493be474998a

And if by chance, anybody else is reading this and is curious about that
post, then needless to say, don't try explaining it to Mr DAB here,
because as the long thread that followed showed, he WILL NOT get it.

More "but you said" stuff to follow now, I expect. :-)

--
Dave Farrance

On 26 Oct 2005 04:48:35 -0700, wrote:
I see. So you don't want to give your name, but you want me to say which
hi-fi mag I write for? No, I don't want to, sorry.

That's because there *is* no magazine, is there. It's just a figment
of your imagination, isn't it. Either that or a down-right
lie used in a sad attept to boost your own credibility. Neither of
which shows you in a very positive light, do they?

In fact Steve Green does write for a hi-fi mag. Every month. It's an
interesting read as well. If Steve isn't going to tell you which mag
then I won't either, but it's one of the upmarket, intelligent ones.
You'd better get down to WH Smiths!

TBH Bill, I don't really care if he does or doesn't. What I do object
to is his arrogance in thinking that just because he has degrees and
has read loads of papers he automatically has a more valid opinion
than others here. He may well do, and he may well be right in what
he says, but using the "I've got loads of degrees and know more than
you do so who are you to question me" argument is just stupid,
ignorant, and immature. His views are only an opinion, and clearly
not one shared by everybody. He'd get far more credence if he
accepted that, and was a little less quick to dismiss others' views
as worthless.

--
Nobby