Freeview audio quality compared to DAB.

Zathras wrote:
On Tue, 07 Aug 2007 19:51:42 GMT, "DAB sounds worse than FM"
[email protected] wrote:

I said that I don't intend to get into an argument about this again,
but I maintain that people who support the full ban when there was a
perfectly workable compromise solution are members of the Nazi party.

Nonsense..gibberish! There are more than a few key differences between
the Nazis and the Labour party - maybe you are ill equipped to see
that though. For a start, when the Nazis disliked a group they were
exterminated - you're still here!


Perhaps you didn't see me repeatedly say that I didn't want to waste my time
getting into an argument about the smoking ban? If you didn't see them, see
previous posts for details.


But you're forgetting that I don't care whether you think I'm
credible or not,

I wasn't forgetting a thing..this is a News Group and I'm no noob.


Oooooooooooo, my knees started quivering when I read that.


because I know I'm credible or else they wouldn't have done what I'd
recommended they should do.

Eh? You're now claiming some sort of credit from idiots that are now,
allegedly, following *your* instructions? High praise indeed.


Put it this way, I helped to bring down the DAB system that was meant to
replace the ubiquitously available global system that is called FM. Out of
interest, what have you ever influenced of any importance?


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

"tony sayer" wrote in message
...
A compressor is not the correct device to prevent this . A compressor
is used to compress the modulating signal's dynamic range - hence its
name. As no Transmitter would be allowed to overmodulate and cause
interference by the producing sideband splatter some for of limiter
would be used - this is a different beast to a compressor.

Yes...


So - the bandwidth of a normally operating AM transmitter does not
depend on amplitude but on the bandwidth of the modulating signal.
Thie upper frquency of this being restricted to about 4.5khz in the
UK, if I remember correctly.

And Yes...
--
Tony Sayer

Fair enough; however my main point was that the audio quality prior to
encoding is relatively poor these days mostly because of the excessive
dynamic range compression , such that it sounds somewhat like AM
transmissions, albeit with greater audio bandwidth?
I assumed that there was some technical reason why AM transmissions have
been subjected to compression for much longer.

Hasn't there been a campaign lately against such excessive compression /
processing?

This fellow has something to say on the issue of compression on recordings:-
http://georgegraham.com/compress.html

Paul

On Wed, 08 Aug 2007 09:51:15 GMT, "DAB sounds worse than FM"
[email protected] wrote:

Perhaps you didn't see me repeatedly say that I didn't want to waste my time
getting into an argument about the smoking ban?

Perhaps I did?

Oooooooooooo, my knees started quivering when I read that.

Oh dear me! I was, simply, reinforcing my point that you continue to
make idiotic arguments based on guesswork.

I helped to bring down the DAB system that was meant to
replace the ubiquitously available global system that is called FM.

Really? DAB was a failure out of the box (nothing to do with you).
When the public didn't buy into it (nothing to do with you), it was
only a matter of time until manufacturers lost interest (nothing to do
with you) and then forced the issue.

The powers that be would have ignored you (if they ever heard of you).
They would have written you off as a whiner complaining about
something new he didn't like even if they paid you any lip service.

Out of interest, what have you ever influenced of any importance?

The incorrect inference here is that you've influenced something
important and I haven't? Sorry but, I'm too modest for that and don't
need any self-generated congratulation or back patting.

I know you won't take any advice but, I'd be *very* tempted to wait
until I hear the transmitted signal before saying how great it is and
you are.

--
Z

Zathras wrote:
On Wed, 08 Aug 2007 09:51:15 GMT, "DAB sounds worse than FM"
[email protected] wrote:

Oooooooooooo, my knees started quivering when I read that.

Oh dear me! I was, simply, reinforcing my point that you continue to
make idiotic arguments based on guesswork.


Such as?


I helped to bring down the DAB system that was meant to
replace the ubiquitously available global system that is called FM.

Really?


Really.


DAB was a failure out of the box (nothing to do with you).
When the public didn't buy into it (nothing to do with you), it was
only a matter of time until manufacturers lost interest (nothing to do
with you) and then forced the issue.


You haven't got a clue what you're going on about. There's something like
250 different DAB models, there's been 5m DAB receivers sold due to the
massive amount of advertising it has received, and the intention was for the
whole of Europe to adopt DAB.

Basically, what went on was that I wrote a few long technical web pages that
put numbers to what was wrong with the DAB system - the combination of using
a highly inefficient audio codec with an inefficient transmission system
meant that modern systems were up to 7 times more efficient than DAB and up
to 12 times cheaper to transmit per radio station than DAB. These pages
attracted quite a lot of attention from broadcasters, and despite the
WorldDAB people and the UK broadcasters trying desperately to convince other
European countries to use the old DAB system, other countries one by one
decided not to adopt it. The first was France, and the French broadcasters
quoted my website pretty much verbatim on the subject of what was wrong with
the DAB system and they quoted my website pretty much verbatim on the
example country's implementation for why it was a bad idea to use DAB: the
UK's implementation. I was proposing that DVB-H and/or DMB should be used as
the main systems for digital radio, and I think 4 out of 5 of the big French
radio broadcasters said that they wanted to use DVB-H or DMB - these are
mobile TV systems, not radio systems, and yet they said they wanted to use
exactly what I had recommended on the web pages I'd written on the subject.
Then I helped some Swedish guys with the technical arguments against DAB,
and they appeared on the radio and wrote magazine articles and were in
contact with their government's media committee, and although it was on a
knife-edge, the Swedish government refused to fund Swedish Radio's plans to
use DAB as well. And the Australian government also refused to allow their
broadcasters to use DAB. Then the Dutch goverment stalled DAB to wait for
new systems in the pipeline, then the German commercial radio groups said
DAB should be modernised or switched off - although by this time DAB was
already dead and buried. If either France or Sweden had adopted DAB it all
could have been very different, because if either country had adopted it
that would have given the confidence to other countries to adopt it as well,
but they didn't, and here we are.

I also used to post on the Radio-L forum, which I knew that a lot of the
technical people who worked on DAB frequented, and I just kept on banging
home the fact that DAB is **** compared to the mobile TV systems. Some
people have called it a campaign of fear, uncertainty and doubt (FUD), but I
like to look at it is highlighting the fact that there were miles better
technologies available, and it was ridiculous to continue using the old DAB
system.

Basically, within the space of about 12 months in 2005, the situation
changed from everybody expecting DAB to be adopted by all European countries
and the other countries that had been backing it, to a series of decisions
that all went against DAB, and then DAB was dead in the water.

I'm hardly saying that it was all down to me here, but I undoubtedly
influenced people and therefore helped to bring about the downfall of DAB.
And even though that may sound big-headed, I'm absolutely certain that it is
true - I was there, you weren't.


The powers that be would have ignored you (if they ever heard of you).


Oh, they were well aware of me. Radio's only a smallish business really, and
DAB is just a small part of the radio business, and I was making so much
noise that they couldn't ignore me. My spies in two countries said that when
my website was brought up in conversation the lovely people from WorldDAB
said that my website's inaccurate and shouldn't be trusted. NRK, the
Norwegian equivalent of the BBC also wrote a report which included a half
page section just about little old me, and they just slurred me and my
website, and lied about my knowledge of digital radio. But I got my own back
by writing 2 newspaper articles for Norwegian papers slagging off NRK's
decision to back DAB.


They would have written you off as a whiner complaining about
something new he didn't like even if they paid you any lip service.


The problem for them was that I'd just taken an MSc in DSP and digital
comms, i.e. the exact subjects that relate to DAB, so I'd just been taught
loads of cutting edge stuff, and it equipped me to easily pick up the stuff
that I hadn't been taught but needed to know with regards to digital radio,
so it was a piece of **** to massacre DAB's 1980s technologies. Basically
they knew I knew my stuff, although that didn't stop them trying to slur my
knowledge, because basically they're a bunch of dishonest toe rags.


Out of interest, what have you ever influenced of any importance?

The incorrect inference here is that you've influenced something
important and I haven't? Sorry but, I'm too modest for that and don't
need any self-generated congratulation or back patting.


Or in other words, you haven't influenced anything of any importance.

Basically, I will never need any encouragement to wind up the DAB
supporters, and there's a few on here, so if you don't want to see any
self-congratulations, you shouldn't really given me an excuse by trying to
patronise me. Anyway, I think I've said all I need to say.


I know you won't take any advice but, I'd be *very* tempted to wait
until I hear the transmitted signal before saying how great it is and
you are.


Why would I want to do that? There are free AAC+ software encoders (such as
Nero's excellent one) that you can download off the 'net, so I can hear what
AAC+ sounds like at whatever bit rate today, and I know what the bit rates
are likely to be, so I know what the audio quality is likely to be like. Oh,
I forgot, you know jack**** about this, don't you.


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

The message
from "Paul" contains these words:


"John Evans" wrote in message
...
On Tue, 7 Aug 2007 15:30:15 +0100, "Paul"
wrote:


Anyway, they all sound crap now due to excessive analogue
compression, including FM transmissions, so everything sounds like
medium wave AM!

Please explain.


By "analogue compression", he presumably means dynamic range
compression,
AKA audio processing, as opposed to data or digital compression, for
example AAC, MP2, MP3 etc.

I mentioned AM radio because analogue
compression has been applied for years to limit the bandwidth of the
transmission, which is quite justifiable.

Surely not. The bandwidth of an AM transmission depends on the
frquency range of the modulation.

As long as it is not overmodulated, but a quick Google search reveals:-
"The maximum value that m can have (in AM) is, without causing distortion,
1.0 or 100%. At this point, the amplitude of the modulated RF signal is
reaching 0 on the negative peaks of the modulated signal. If m exceeds 1.0,
overmodulation occurs. When m exceeds 1.0, the modulator output is zero
during times when the modulating signal is not zero. As a result, the
amplitude of the modulator output no longer follows the amplitude of the
modulating input. Additional sidebands appear at frequencies farther
removed
from the carrier, increasing the bandwidth of the signal. When an
overmodulated signal is received, the distortion produces a distinctive
"splattering" sound in the recovered audio; thus AM overmodulation is
sometimes called sideband splatter."

The maximum value of m is limited to 100% only for the negative half
of the modulating waveform. There is no limit (ignoring technical issues
of peak voltage limits in the transmitting equipment itself) for the
positive halves of the modulating waveform.

This fact was (and still is) used to maximise the range of an am
transmitter when the modulation involves human speech (talking or
singing). The human voice produces a lot of asymetric harmonics (in
terms of spl and consequent voltage peaks from a microphone). This
attribute can be put to good use in the case of am transmitters.

A properly designed am transmitter will employ limiter circuits
designed to avoid overmodulation in the negative direction (i.e.
designed to prevent the undesirable carrier cut off that results which
is the cause of sideband splatter[1]). The positive peaks of modulation
can safely be allowed to exceed 100%, perhaps reaching 300% or more in
extreme circumstances provided the transmitter can handle the voltages
involved.

Since it is common practice to let the transmitter's limiter do some
work, all that is necessary is to provide a phase reverser that
autodetects the asymetry and reverses the phase so as to always present
the transmitter's modulator with positive peaks that are stronger than
the negative peaks.

Since switching phase during the loud parts of the modulation leads to
noticable transients, the phase switcher will await the next opportunity
of quietness to silently slip in a reversal of phase. For a music
station, this works fine for music tracks involving a solo singer or
recordings involving 2 or more singers where the recording studio
actually managed to get the microphones all in the same phase.

The difference between the right phase and the wrong phase could be
worth a doubling (or halving) of the transmitter's range (effectively
6db). Sadly, there were a few examples of pop recordings involving a
duet with oppositely phased microphones that fooled the phase reversing
circuit into switching to the wrong phase at each change of voice. These
particular tracks ended up sounding much quieter over am [2] than they
need have been if the recording engineer had paid any attention to
unifying the phase of the vocalist's microphones.

[1] Sideband splatter does _not_ refer to the effect it has on the sound
of the tuned in station (although it will add some distortion). It
refers to an effect on its neighbouring stations in the frequency band
it operates in. IOW, sideband splatter is interference to adjacent
channels.

[2] This effect is limited to am transmissions only. It doesn't apply to
fm transmissions whereby the deviation limiters have to limit both
positive and negative deviations of frequency equally.

HTH

--
Regards, John.

Please remove the "ohggcyht" before replying.
The address has been munged to reject Spam-bots.

On Wed, 08 Aug 2007 19:14:21 GMT, "DAB sounds worse than FM"
[email protected] wrote:

Zathras wrote:
On Wed, 08 Aug 2007 09:51:15 GMT, "DAB sounds worse than FM"
[email protected] wrote:

Oooooooooooo, my knees started quivering when I read that.

Oh dear me! I was, simply, reinforcing my point that you continue to
make idiotic arguments based on guesswork.

Such as?

Sorry..I'm not going to help you out with your obvious reading
problems.

I look forward to the next better-than-FM radio implementation but
will believe it when I hear it not when someone bleats on about how
excellent they are..ok?

As I know the remaining slab of text will, undoubtedly, be full of
presumptuous, self-congratulatory twaddle, I'll pass on reading it.
Nazis can do that sort of thing..

snip

--
Z

Zathras wrote:

I look forward to the next better-than-FM radio implementation


Next? There hasn't been one that's better than FM yet.


but
will believe it when I hear it not when someone bleats on about how
excellent they are..ok?


There's a simple way to avoid me bleating on about how excellent I am, and
that's to not try to belittle me in the way that you did.


As I know the remaining slab of text will, undoubtedly, be full of
presumptuous, self-congratulatory twaddle, I'll pass on reading it.


I've said what I want to say, thanks.



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

On Thu, 09 Aug 2007 09:57:41 GMT, "DAB sounds worse than FM"
[email protected] wrote:

There's a simple way to avoid me bleating on about how excellent I am, and
that's to not try to belittle me in the way that you did.

*You* supplied the material with your idiotic and offensive
generalisation that smoking ban supporters are Nazis. You did your own
belittling..

--
Z

Zathras wrote:
On Thu, 09 Aug 2007 09:57:41 GMT, "DAB sounds worse than FM"
[email protected] wrote:

There's a simple way to avoid me bleating on about how excellent I
am, and that's to not try to belittle me in the way that you did.

*You* supplied the material with your idiotic and offensive
generalisation that smoking ban supporters are Nazis. You did your own
belittling..


Clearly you have an extremely short memory. Here's what you wrote:

"DAB was a failure out of the box (nothing to do with you).
When the public didn't buy into it (nothing to do with you), it was
only a matter of time until manufacturers lost interest (nothing to do
with you) and then forced the issue.

The powers that be would have ignored you (if they ever heard of you)."


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

Mizter T wrote in
ups.com:

On 6 Aug, 17:13, "DAB sounds worse than FM" [email protected] wrote:

(snip)

The BBC at least will provide higher quality on DAB+.


If and when that happens.

There are absolutely no concrete proposals, let alone plans, to
transfer over to DAB+ by either the BBC or the commercial
broadcasters.

Bear in mind that there are now 5 million DAB sets out in the wild,
the vast majority of which can't be upgraded to DAB+, and no
broadcasters - having encouraged listeners to convert to DAB receivers
- are going to be keen on alienating those with this equipment. No
amount of wishful thinking will change that.

It's a shame because the DAB+ technology would certainly appear to be
preferable. We are however where we are.


The big problem with DAB is that MP2 is an old and not very good codec and
needs at least 192kbps to be subjectively like MP3 at 128kbps or AAC+ at
about 96kbps. This corresponds to "near-CD quality". However, Ofcom's
perceived wisdom that "more is better" applied it to channels rather than
bandwidth resulting in lots of horrible sounding stations on DAB.

Analogue compression (companding) is a separate issue and is [over]used on
all broadcasts except I think on BBC Radio 3.

According to Commercial Radio Australia, "DAB+ implements AAC+ as the audio
compression codec, a far more modern technology which is an extension of
the MPEG4 Advanced Audio Codec. 'Better-than-FM' quality audio can be
compressed into as little as 64 kilobits per second, compared with around
160kbps for the earlier DAB standard."

See http://www.digitalradiotech.co.uk/bi...vs_quality.htm for subjective
compression graphs describing how annoying the perceived digital
compression is.

MP2 at 128kbps is described as "annoying" (96kbps is "very annoying")
MP3 at 128kbps is "slightly annoying"
AAC at 128kbps is "not annoying" (96 kbps is "slightly annoying")

Unfortunately the vast majority of UK DAB is therefore "annoying" with the
exception of Classic FM (annoying/slightly annoying) and BBC R3 (slightly
annoying). A good FM signal is not annoying.

The Estonians introduced DAB at 320kbps which sounds like a good idea. Pity
the UK didn't.

Freeview and Digital satellite has the advantage of a bit more available
bandwidth and therefore the MP2 compression can be less than on DAB.

Regards
Peter