11A DAB from Emley: I'm excited

"Martin" wrote in message
...
Apart from Norway, which is switching off FM radio next year, are
other European countries also planning to do the same?

I don't think the Dutch have plans. DAB is a big flop. Only tens of
thousands of
receivers were sold which can receive DAB in NL

DAB was a great idea badly implemented. One of the problems with all digital
broadcasting is that it allows the broadcaster to choose the level of
(lossy) compression on each of the channels that make up each of the
multiplexes. And time and again, greed (cramming in as many channels as
possible) wins over quality.

The thought that some radio channels are transmitted in as little as 32
kb/sec mono shows how far they have stooped.

I've not listened to a good FM radio for several years now - I've never set
up my 1980s vintage hifi system in my new house. I tend to listen to the
(FM) radio in the car where there's a lot of background road noise, or else
I record/listen on Freeview. My impression is that Radio 4 on Freeview at
192 kb/sec stereo has just a hint of distortion, even if it's free of FM
stereo hiss. One thing I've noticed from examining the waveform in Audacity
as I've been editing out continuity announcements is that the waveform often
looks asymmetrical: negative peaks are larger amplitude than positive peaks
(or vice versa). I wonder what effect that would have on sound quality:

http://s28.postimg.org/4z902kib1/Image1.png

On 17/02/2016 10:26, Max Demian wrote:
On Wed, 17 Feb 2016 09:03:13 +0000, Mark Carver
wrote:
On 16/02/2016 18:38, Graham. wrote:
Roderick Stewart Wrote in message:

I guess so. A supermarket near here usually has blaring from its
ceiling something that announces itself as "Asda FM", though it
doesn't seem to be available on the FM broadcast band.

It might have started life as an FM subcarrier in the Ku band.
Just a thought.

Actually, I think it did. However, it's almost certainly called
Asda FM,
simply to 'market' it as a 'regular' radio station.

Like hospital 'radio' which was presumably always delivered by wire from
a studio on the premises.

Ohh no! They broadcast (mostly on AM) and in theory you can only pick it
up on the premises, but actually it goes for miles. They also have links
to other hospitals, some using 50MHz.

Bill

On 17/02/2016 11:19, NY wrote:

One thing I've noticed from examining the
waveform in Audacity as I've been editing out continuity announcements
is that the waveform often looks asymmetrical: negative peaks are larger
amplitude than positive peaks (or vice versa).

Could that be caused by a small DC differential between the ground
potentials of different parts of your equipment?

Bill

"Bill Wright" wrote in message
...
On 17/02/2016 11:19, NY wrote:

One thing I've noticed from examining the
waveform in Audacity as I've been editing out continuity announcements
is that the waveform often looks asymmetrical: negative peaks are larger
amplitude than positive peaks (or vice versa).

Could that be caused by a small DC differential between the ground
potentials of different parts of your equipment?

That's a recording of the transmitted MPEG stream from Freeview, so there's
no conversion to analogue (with the possibility of introducing DC bias) and
then conversion back to digital for recording it. And wouldn't DC bias
always be the same sign, whereas this alternates in different parts of the
waveform. Maybe I'm assuming that waveforms from a microphone will always be
symmetrical and that's not the case.

On 17/02/2016 13:26, Bill Wright wrote:

Like hospital 'radio' which was presumably always delivered by wire from
a studio on the premises.

Ohh no! They broadcast (mostly on AM) and in theory you can only pick it
up on the premises, but actually it goes for miles. They also have links
to other hospitals, some using 50MHz.

Yes, listed he-

Use the MF tab, and do a sort on 'Hospital' in column D

http://stakeholders.ofcom.org.uk/binaries/broadcast/guidance/tech-guidance/tech-parameters/TxParams.xls


--
Mark
Please replace invalid and invalid with gmx and net to reply.

On Wed, 17 Feb 2016 13:51:09 +0000, NY wrote:

"Bill Wright" wrote in message
...
On 17/02/2016 11:19, NY wrote:

One thing I've noticed from examining the
waveform in Audacity as I've been editing out continuity announcements
is that the waveform often looks asymmetrical: negative peaks are
larger amplitude than positive peaks (or vice versa).

Could that be caused by a small DC differential between the ground
potentials of different parts of your equipment?

That's a recording of the transmitted MPEG stream from Freeview, so
there's no conversion to analogue (with the possibility of introducing
DC bias) and then conversion back to digital for recording it. And
wouldn't DC bias always be the same sign, whereas this alternates in
different parts of the waveform. Maybe I'm assuming that waveforms from
a microphone will always be symmetrical and that's not the case.

For quite a lot of musical instruments (including the human voice)
that's most definitely *not* the case.

I recall a magazine article from 3 or 4 decades back (most likely
"Studio Sounds" magazine) referring to the effect of using oppositely
phased vocalists microphones on a commercially recorded album involving
two vocalists (istr Stevie Wonder being one of the vocalists in question
- details are now hazy and google is no fekin' help as always in this
sort of search).

Back then, AM radio stations were still the main conduit by which "The
Music Industry" advertised its wares (i.e. Pop Radio stations' source of
the popular music they pumped out in between the more crass of their
commercial outpourings in the US of A).

The AM station broadcasters used amplitude limiters at the transmitters
to limit the negative excursions to no more than 95% to save them
committing the cardinal sin of generating broadband splatter interference
which results whenever the carrier is modulated by more than 100% on the
negative modulation peaks.

Most human voices, whether singing or talking, have a very asymmetric
waveshape as seen on a 'scope so it's important to arrange the phasing
between the microphone (wherever that was located to begin with) and the
TX modulator so that the positive half of the sound pressure wave hitting
the front of the microphone's diaphragm corresponds to positive
modulation in order to avoid the anti-splatter modulation circuit
reducing the service range of the TX.

This range reduction effect was considered so critical that the anti-
splatter modulation control incorporated an asymmetry detection circuit
to control a phase reversing circuit which was designed to sneak in any
necessary reversals during quiet levels of modulation in order to avoid
causing a massive transient if allowed to take place at full modulation
levels.

The more observant can probably see where all this is leading to but
I'll finish my anecdote anyway. The studio engineers' carelessness in
matching microphone phase between the two vocalists (the issue wasn't
spill-over, btw) resulted in an album's worth of tracks that effectively
reduced the service range of any AM transmitter that tried to broadcast
their shoddy efforts.

It didn't matter that the track might start off nice and loud. As soon
as one of the duet passed to the other vocalist, the TX limiters would be
forced to reduce the modulation whilst the auto phase reverser awaited
its next opportunity to sneak in the required reversal which, in this
case, was during the moment of quietness on the next pass back to the
first vocalist at which point the phase would need to be reversed yet
again in order to allow full asymmetric modulation to be achieved (and so
it would continue for as long as the duet kept taking turns).

I can't recall whether or not the studio did a remixed master in order
to press copies that they could re-issue to the AM broadcasters to effect
a louder AM broadcast. For anyone auditioning the vinyl more directly or
via an FM broadcast, the mismatched phase between the vocalist's
microphones would have very little deleterious effect (even when mixed
down to mono - as of course would be the case for an AM broadcast).

Having read that article around the time that I'd just gotten into
carting my R2R tapedeck (along with a homebuilt 6 plus 2 channel[1]
mixing unit with remote stage box linking the audio over balanced pair
cable) around the local pubs and clubs to record live performances as a
service, I was motivated to incorporate reversing switches on the stage
box and add a phase polarity detection circuit to the mixer box which
relied on getting someone to say "Ahhhhh" quite loudly into each
microphone so that I could check and correct the polarity of the
vocalist's microphones (the stage box was used to intercept the original
cabling to the group's own PA kit, typically Hi-Z microphones - sadly, by
the time I discovered a need to upgrade the middle two channels in the 6
channel interceptor box to handle Lo-Z balanced microphones where I'd had
to resort to taping a couple of my own microphones alongside of the
vocalists microphones[2], it was just too late for me to enjoy the
upgrade since I never faced such a scenario again before finally quitting
this part time activity).

[1] The plus 2 channel was (still is) the stereo microphone channel I
used for "miking up" the drum kit in live gig settings. I'd bought myself
a half decent Aiwa electret single point stereo microphone which, rather
conveniently, was supplied with a frequency response chart allowing me to
equalise the 6dB per octave bass roll off from 200Hz down to level up its
response to the bass drum(s). In essence it was a practical way to
capture the drum kit in a live non-studio setting.

I simply set it up in front of the kit as far forward as I could get
away with without interfering with the activities of the walk-around
members of the band. It wasn't perfect and I *just* might have placed it
behind the drummer in some recording locations (I'd have had to swap left
for right to compensate this change of location) but can't really recall,
some three decades on (late 70s/early 80s), whether or not I actually did
so.

[2] As you might imagine, such taping of mics alongside of the vocalists'
own mics was a less than satisfactory solution. Although it was better
than nothing, it wasn't all that much better. Unfortunately, I was mixing
straight to stereo so there's no way of going back to a multi-track
recording to tweak the individual microphone levels post session. :-(

--
Johnny B Good

Mark Carver Wrote in message:
On 16/02/2016 18:38, Graham. wrote:
Roderick Stewart Wrote in message:
On Tue, 16 Feb 2016 04:47:38 +0000, Bill Wright
wrote:

Jazz FM Stereo (is 'FM' still a buzzword?)

I guess so. A supermarket near here usually has blaring from its
ceiling something that announces itself as "Asda FM", though it
doesn't seem to be available on the FM broadcast band.

Rod.


It might have started life as an FM subcarrier in the Ku band.
Just a thought.

Actually, I think it did. However, it's almost certainly called Asda FM,
simply to 'market' it as a 'regular' radio station.



--
Mark
Please replace invalid and invalid with gmx and net to reply.


It's strange that that station nameing hasn't evolved to include
the word "digital" as everyone knows, anything that is digital
must be better.
--

%Profound_observation%


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Mark Carver Wrote in message:
On 17/02/2016 13:26, Bill Wright wrote:

Like hospital 'radio' which was presumably always delivered by wire from
a studio on the premises.

Ohh no! They broadcast (mostly on AM) and in theory you can only pick it
up on the premises, but actually it goes for miles. They also have links
to other hospitals, some using 50MHz.

Yes, listed he-

Use the MF tab, and do a sort on 'Hospital' in column D

http://stakeholders.ofcom.org.uk/binaries/broadcast/guidance/tech-guidance/tech-parameters/TxParams.xls


--
Mark
Please replace invalid and invalid with gmx and net to reply.


I can't see that document property on my phone at the moment.
How much deviation is allowed on these links, are they just mono?
--

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On 16/02/2016 13:25, Max Demian wrote:
On Tue, 16 Feb 2016 04:07:51 -0800 (PST), "R. Mark Clayton"
wrote:
On Tuesday, 16 February 2016 08:37:46 UTC, Roderick Stewart wrote:
On Tue, 16 Feb 2016 04:47:38 +0000, Bill Wright
wrote:
Jazz FM Stereo (is 'FM' still a buzzword?)
I guess so. A supermarket near here usually has blaring from its
ceiling something that announces itself as "Asda FM", though it
doesn't seem to be available on the FM broadcast band.

It is broadcast by satellite, NOT on FM
Telstar satellite at 15.0°W, 11.502 H, SR 6620, FEC 2/3 however I
would guess that newer stores would use the web
http://www.asda.com/asda-fm.html

" This plug-in is not supported "


The actual 48k WMA stream is at http://audio.asdafm.com/ASDAFMLive .
If you stick that in Windows Media Player, VLC, MPC-HC or something it
will play.

--

Brian Gregory (in the UK).
To email me please remove all the letter vee from my email address.

On Sat, 20 Feb 2016 02:20:19 +0000, Brian Gregory
wrote:
On 16/02/2016 13:25, Max Demian wrote:
On Tue, 16 Feb 2016 04:07:51 -0800 (PST), "R. Mark Clayton"
wrote:

It is broadcast by satellite, NOT on FM
Telstar satellite at 15.0°W, 11.502 H, SR 6620, FEC 2/3 however I
would guess that newer stores would use the web
http://www.asda.com/asda-fm.html

" This plug-in is not supported "

The actual 48k WMA stream is at http://audio.asdafm.com/ASDAFMLive .
If you stick that in Windows Media Player, VLC, MPC-HC or something
it
will play.

Actually I'm not all that interested :-)

--
Max Demian