DAB Performance of different makes?

On Fri, 28 Oct 2005 13:27:10 GMT, DAB sounds worse than FM wrote:

Actually, I did read your posts on Google Groups this morning to see
your reaction to being blocked,

LOL. So I was right - you couldn't resist seeing what I'd say about
it. I hope my lack of concern didn't dissappoint you too much.
How sad.

Also, if you did that you'll know why your filter failed - simply
because I post from several computers that were configured slightly
differently. You'll also know that I fixed the problem. You might
guess that this and the last post (and only those) on this branch were
in turn deliberately altered so that you *would* see them. Otherwise
I've no desire for you to see my posts, so please don't be disallusioned.
Anyway, it does mean I can be rude about you without offending you
directly ;-) (oops, sorry, winked at you). Of course, when you do
grow up, you'll realise that your penis won't drop off if you simply
ignore someone you don't like. Killfiling is a little like sticking
your fingers in your ears, closing your eyes and going "Nanananana
can't hear you" which many of us gave up before reaching our teens.

You could also filter on "Nobody Here.*invalid" if you wanted, because
I've no intention of changing the final "invalid" because it's naughty
to post from an otherwise valid domain, and invalid is a special
invalid domain. I've no desire to change my moniker either. So,
hopefully this'll be the last post you'll ever ever see from me.

Hurrah!

--
Nobby

In article ,
DAB sounds worse than FM wrote:
Actually, I did read your posts on Google Groups this morning to see
your reaction to being blocked,

Goof grief.

--
*What do little birdies see when they get knocked unconscious? *

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

Alan White wrote:
On Fri, 28 Oct 2005 12:18:35 GMT, "DAB sounds worse than FM"
wrote:

Alan White wrote:
On Fri, 28 Oct 2005 10:06:13 +0100, Jim Lesurf
wrote:

Does anyone else think that what I have been saying was unclear and
"ambiguously worded"?

No, it was perfectly clear.


Hahahahahhahahahahahahahahahahhahahahahhahaha.


That sounds like a jackass.

See:-

http://aviary.owls.com/kookaburra/kookaburra.html

Oi. Don't go comparing Stevie-buy to a kookaburra. One of them's really
quite smart, considering ;-)

--
Nobby

"DAB sounds worse than FM" wrote in message
...
Nobody Here wrote:
On Fri, 28 Oct 2005 08:59:55 +0100, :::Jerry:::: wrote:

snip

Are you suggesting that he is nothing but a rant-boy?! :~)

Well, I dunno, this has been a pretty long thread - perhaps I was
wrong about the debating, 'coz he obviously likes a mass debate
:~)


Look, I've put you in my killfile. Get the message. If you continue
to
try and circumvent my killfile filter then I will have no other
option
than to send a short email to .

*plonk* (again)


Well, if you can do that, you can also be complained about, you post
using more than one ID, nymph-shifting is enough to get you kicked
off Usenet alone, you then also abuse the domain name system with
your rant mode return address, and then there is your sag's line
length...

Better to just learn how to use a kill-file, considering that you
have been given some tips on how to block the person.

:::Jerry:::: wrote:

"DAB sounds worse than FM" wrote in message
...
Nobody Here wrote:
On Fri, 28 Oct 2005 08:59:55 +0100, :::Jerry:::: wrote:

snip

Are you suggesting that he is nothing but a rant-boy?! :~)

Well, I dunno, this has been a pretty long thread - perhaps I was
wrong about the debating, 'coz he obviously likes a mass debate
:~)


Look, I've put you in my killfile. Get the message. If you continue
to
try and circumvent my killfile filter then I will have no other
option
than to send a short email to .

*plonk* (again)


Well, if you can do that, you can also be complained about, you post
using more than one ID, nymph-shifting is enough to get you kicked
off Usenet alone, you then also abuse the domain name system with
your rant mode return address, and then there is your sag's line
length...

Nymph-shifting? Is that carting little people around in the woods :-)

But nevertheless, there's no "usenet" authority to kick anyone off.
Remember usenet is just a random collection of interoperating servers
which just accept posts from their peers and forward any they have
to any others they know about. There are no "rules" in any binding or
legal sense - there are only a set of guidelines about what is and is
not acceptable behaviour. That's partly why top-posting nazi rants are
so irritating, because although it's preferable to bottom post, and
it makes sense to do so, and a whole bunch of other good reasons for
doing it, it's only a guideline, and it's not one that fits all
circumstances. The same with return and from adresses, they're
just text and no "usenet" body can force you to do anything, simply
because none exists. It's barely supressed anarchy out there, and
if you don't believe that look on some of the alt.* or uk.local groups!

Your ISP, on the other hand, might have rules in its AUP or T&Cs that
prohibit you from doing stuff on usenet, or more specifically their
usenet servers. That varies - some don't care, some don't.
Mine, for example, insists on either a valid domain in any
fields you fill in that is resolvable to you, or a correct invalid
one, like I use. as long as you end it with ".invalid" you can more
or less stick what you like in front of that. Some news readers
might enforce some format on the fields too. Certainly most will
prohibit you from posting some stuff, particularly some types of
material. None, however, will give a **** about a spat between
two twerps on any group, fiddling with your apparent name, or even
top posting (gulp) to your heart's content.


--
Nobby

On 28 Oct 2005 15:51:06 GMT, Nobody Here wrote:


| But nevertheless, there's no "usenet" authority to kick anyone off.

What is this then?
http://www.plus.net/info2/legal/index.html
--
Dave Fawthrop dave hyphenologist co uk
Help make Usenet a better place: English is read downwards,
please don't top post. Trim replies to quote only relevant text.
Check groups.google.com before asking an obvious question.

Dave Fawthrop wrote:
On 28 Oct 2005 15:51:06 GMT, Nobody Here wrote:


| But nevertheless, there's no "usenet" authority to kick anyone off.

What is this then?
http://www.plus.net/info2/legal/index.html

That's an ISP's T&Cs. It's not a "usenet authority". I mentioned ISP's
T&Cs later on in my post. They can't "kick you off usenet", if you sign
up with another ISP then you still have full usenet access. Same if
you post via news.individual.net or whatever it's called, for example,
and even if they were to deny you access to any nntp server there's
still google on http. The only way you can be kicked off usenet would
be iff all the thousands and thousands of usenet servers all around
the world all decided to stop accepting and propogating your posts.
Seeing as you have no fixed identity, that's implausable.

Interestingly, PlusNet don't seem to have a separate usenet AUP, I
thought they did. They could apply

14.1.2 to send, knowingly receive, upload, download or use any
material which is or may be offensive, abusive, indecent, defamatory,
obscene or menacing, or in breach of any Intellectual Property Right,
confidence, privacy or any other rights;

14.1.3 to cause annoyance, inconvenience or needless anxiety;

because I've clearly offended, annoyed and inconvenienced Stevie
Wonder-boy, and there I go being abusive, but I somehow think they'd
be pushing it - I suspect they'd have to get rid of 90% of their usenet
users for one transgression or another - Stevie'd be right in there too
coz I suspect he's abused, annoyed and offended many more people than
I have over the years :-)


--
Nobby

"Nobody Here" wrote in message
...
:::Jerry:::: wrote:

"DAB sounds worse than FM" wrote in message
...
Nobody Here wrote:
On Fri, 28 Oct 2005 08:59:55 +0100, :::Jerry:::: wrote:

snip

Are you suggesting that he is nothing but a rant-boy?! :~)

Well, I dunno, this has been a pretty long thread - perhaps I
was
wrong about the debating, 'coz he obviously likes a mass
debate
:~)


Look, I've put you in my killfile. Get the message. If you
continue
to
try and circumvent my killfile filter then I will have no other
option
than to send a short email to .

*plonk* (again)


Well, if you can do that, you can also be complained about, you
post
using more than one ID, nymph-shifting is enough to get you
kicked
off Usenet alone, you then also abuse the domain name system with
your rant mode return address, and then there is your sag's line
length...

Nymph-shifting? Is that carting little people around in the woods
:-)

But nevertheless, there's no "usenet" authority to kick anyone off.

Agreed, but there are the NNTP (or ISP) hosts, many will consider
name changing as serious abuse.

Remember usenet is just a random collection of interoperating
servers
which just accept posts from their peers and forward any they have
to any others they know about. There are no "rules" in any binding
or
legal sense - there are only a set of guidelines about what is and
is
not acceptable behaviour. That's partly why top-posting nazi rants
are
so irritating, because although it's preferable to bottom post, and
it makes sense to do so, and a whole bunch of other good reasons
for
doing it, it's only a guideline, and it's not one that fits all
circumstances. The same with return and from adresses, they're
just text and no "usenet" body can force you to do anything, simply
because none exists. It's barely supressed anarchy out there, and
if you don't believe that look on some of the alt.* or uk.local
groups!

Agreed, again, but also look from who's servers many of those
messages come through IYSWIM, but then again look who Mr DAB is
posting through...


Your ISP, on the other hand, might have rules in its AUP or T&Cs
that
prohibit you from doing stuff on usenet, or more specifically their
usenet servers. That varies - some don't care, some don't.
Mine, for example, insists on either a valid domain in any
fields you fill in that is resolvable to you, or a correct invalid
one, like I use. as long as you end it with ".invalid" you can
more
or less stick what you like in front of that. Some news readers
might enforce some format on the fields too. Certainly most will
prohibit you from posting some stuff, particularly some types of
material. None, however, will give a **** about a spat between
two twerps on any group, fiddling with your apparent name, or even
top posting (gulp) to your heart's content.


Agreed, yet again, but I suspect that Mr DAB's most serious 'problem'
is the abuse of the domain name system - as that doesn't just effect
Usenet or the persons own ISP, but the whole email system!

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

There will always be bit errors, and different DAB modules will
perform differently.

Yes! That is the kind of thing I have been asking about - with the aim
of identifing the *actual* differences between *specific* RXs in
various specific situations. For the reasons I have (twice) explained.


The output BER is the all-important parameter, and two receivers which
have an identical BER should provide effectively identical output audio
quality (assuming, say, that the audio is routed via S/PDIF to the same
DAC).

I'd agree with the above, but with some qualifiers that are in accord with
what you wrote lower down in your posting.

One is that if different RXs have different sensitivities or level of
interference rejection, then in some reception conditions different RXs
will output different BERs from the same RF input. This is why I think info
on this would be of interest as it may affect some user's choice of RX.

The other is the question of the 'strategy' a given RX takes to deal with a
given sequence of uncorrectable errors when they arise. My experience with
CD players and DACs is that when presented with a disc which produces a
high enough level of uncorrectable errors the results can vary quite
noticably. Thus my curiosity that this may also occur with DAB RXs. Some
make 'mask' the errors in ways that make them less noticable than how other
RXs handle the same sequence of errors, or produce artefacts that some find
more/less annoying than others. This may for some people also matter. I'd
agree that what they should do in improve reception and get down the level
of errors, but for some people this may not be practical. Hence the
usefulness of our finding out how RXs may vary in these respects.

However, even with an identical output BER (the BER after the Viterbi
decoder) there may be very slight differences between the performance of
different DAB chipsets/modules. The possible differences could be
caused by different implementations of the Viterbi algorithm such that
the distribution of uncorrectable errors over the different parts of
the audio frame are different.

I'll explain what I mean by that:

DAB uses UEP (unequal error protection) where different parts of the
audio frame are protected with different error correction code rates:
the audio frame header uses a low code rate for high protection, whereas
the audio samples themselves use a higher code rate and thus offer
lower protection.

Therefore, if different chipsets/modules have implemented the Viterbi
algorithm differently (e.g by using a different constraint length) then
it is possible that the different chipsets/modules output a slightly
different distritution of uncorrectable errors over the different parts
of the audio frame, but still have the same overall output BER.

Thanks for the above explanation. Yes, the above implies that there may be
differences of the kind that I am curious about.

Personally, I think it's unlikely that it is very unlikely that this
would be significant, because the different code rate levels offer
markedly different protection levels to the different parts of the audio
frame, so I would say it is extremely likely that the distribution of
errors over the different protection levels will be the same.

In general, I am inclined to agree. My experience with other systems like
CD players and DAC is that - given good signals - the differences tend to
be slight for well made units. However what worries me in this area is the
apparent lack of measurements and comparisons under a range of recpetion
conditions. Hence we can assume that the differences will, generally, be
small. But I dislike basing this on an assumption, however reasonable. I'd
prefer evidence as my experince in engineering and science is that evidence
sometimes shows unexpected results. e.g. here it may show that *some* RXs
behave is a different way to others, and in a way that would have a
significant effect for some users.

Different receivers will have different RF performance, but this is --
or should be -- pretty irrelevant if the output BERs are equivalent, for
the reason I've just given.

That would be so if the BERs are equivalent, etc. However the problem is
that if their RF sensitivities, etc, differ, then their BERs may also
differ in some conditions of use.

You would expect the MP2 audio decoders would all pass the strict
conformance requirements, but there probably will be very, very slight
differences in the output PCM audio bitstream produced even for the same
input data stream (but due to the strict conformance requirements I
don't think this should be significant to the output audio quality).

Again, I'd agree with that in principle, but I tend to prefer evidence from
measurements on real RXs to see if any of them fall short of what is
assumed or have unexpected 'features' in their behaviour.

[snip]

No, I can't direct you to any evidence.

There's 2 chipset/module design companies: Radioscape and
Frontier-Silicon, and they account for probably 95% or more of all DAB
receivers sold in the UK. They may use different RF front ends, but my
impression is that receivers usually install full modules provided by
these companies. Having said that, from reading people's experiences,
there does seem variability of reception quality for things like DAB
personal radios, so there may be some model-specific stuff as well.

FWIW I bought a cheap 'DAB adaptor' a few weeks ago and use it some of the
time for 'background listening' or for stations like BBC7. As you would
expect, the sound quality on a station like BBC7 or World Service ahem
isn't exactly perfect. This, I expected, of course.

However what I am curious about is the following:

One the main BBC stations the multiplex signal level is good enough for the
RX to display "signal error 0" (whatever that means is undefined). But on,
say, Classic FM, on its multiplex I get "signal error 3" (or a number in
the range 2-5).

Classic FM sounds worse to me that R3. This isn't surprising for reasons
which I think will be obvious. However I am curious to know:

A) Would it sound any better if I improved the signal until I got "signal
error 0"?

B) Would a different RX give better results for the Classic FM multiplex in
the same location?

It seems to me that many users and potential users of BAD... oops DAB would
wonder similar things. Yet it seems that there is a stunning absence of
measured comparison data on actual RXs to guide a potential buyer/user.

[snip]

I have now spent some time trying to find info from makers websites, etc.
There is some data there, but in terms of assessing real commercial RXs it
is remarkably sparse and of little use in terms of practical assessment.

There was a time when the audio mags would do a thorough examination of new
FM tuners, and show a great deal about their noise levels, interference
rejection ability, etc. Yet almost nothing functionally equivalent seems to
be done with DAB RXs. I find this quite baffling, and unsatisfactory since
it fails to provide some potential users with info that they might find
very helpful.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

Jim Lesurf wrote:
There was a time when the audio mags would do a thorough examination of new
FM tuners, and show a great deal about their noise levels, interference
rejection ability, etc. Yet almost nothing functionally equivalent seems to
be done with DAB RXs. I find this quite baffling, and unsatisfactory since
it fails to provide some potential users with info that they might find
very helpful.

I wonder if that's because of the perception that digital (DAB, TV whatever)
either works of doesn't work, and that there's no middle ground? With
most analogue systems their's a broad transition between working and
not working which might make such comparisons more important, or at least
seem to be more important.

Having said that, I think it's more an artefact of the consumer environment
today - that sort of stuff sells on "features" rather than "quality". Also,
the mags, as has been pointed out many times before, have to keep their
advertisers happy.

--
Nobby