Does anyone happen to know about the compression policy for this year's
Proms broadcasts? Could there be a difference between what is going out
on DAB and FM respectively?

On DAB I am getting the impression that compression is absent or reduced
compared with FM, which if true is good news. Switching between DAB and
FM on my Sony tuner, FM seems much louder than DAB on soft bits but not so
different on loud bits. However, the comparison is hampered by the 2-3s
muting when you switch - is this a feature of the Sony or do other
tuners do it? I presume it's to disguise the 1s delay on DAB.

(The actual sound quality of the few broadcasts that I have listened to
this season seems pretty good.)

Patrick Wallace
__________________________________________________ ______________________

In article ,
Rembrandt Q. Einstein wrote:
Thanks very much, this is the sort of stuff I wanted to know. I am
constantly amazed at how good Radio 3 can sound, and it is especially
impressive when you consider the tortuous route that the signal must
navigate before it reaches your ears, and how limited the real quality
of that signal is, in 'audiophile' terms.

It says more that people really don't understand figures - or more that
they can't relate to what they sound like.

--
*Not all men are annoying. Some are dead.

Dave Plowman London SW 12
RIP Acorn

In article , Rembrandt
Q. Einstein writes
Dave Plowman wrote in message news:4c1c657bcadave.so
...
In article ,
Rembrandt Q. Einstein wrote:
Thanks very much, this is the sort of stuff I wanted to know. I am
constantly amazed at how good Radio 3 can sound, and it is especially
impressive when you consider the tortuous route that the signal must
navigate before it reaches your ears, and how limited the real quality
of that signal is, in 'audiophile' terms.

It says more that people really don't understand figures - or more that
they can't relate to what they sound like.

Quite, although the DAB prospect is rather worrying. This is interesting:

http://www.whathifi.com/newsMainTemp...=2&storyID=109

I won't be dumping my Sansui TU-710 yet, especially since it only cost me £20.

Poor old Dan smith. I wonder if he's still at the BBC for speaking the
truth!..
--
Tony Sayer

In article ,
Rembrandt Q. Einstein wrote:
It says more that people really don't understand figures - or more that
they can't relate to what they sound like.

Quite, although the DAB prospect is rather worrying. This is interesting:

http://www.whathifi.com/newsMainTemp...=2&storyID=109

I won't be dumping my Sansui TU-710 yet, especially since it only cost
me £20.

Thing is that all the pop stations on FM are heavily processed. As are AM.
DAB at the current bitrate seems quite capable of equalling the former and
beating the latter, quality wise.

Those stations that one would wish good quality from, like say R2,3 and 4
- and say Classic and Jazz FM - should have a higher bitrate. And no
processing.

However, all the powers that be have decided processing of some sort is
necessary on virtually all stations on all media - it's apparently what
the public want. So it's no surprise that they also want to reduce the
bitrate on DAB to the point where it's audible.

--
*The colder the X-ray table, the more of your body is required on it *

Dave Plowman London SW 12
RIP Acorn

tony sayer wrote:
In article , Frank Johnson
writes

Dave Plowman wrote:

In article ,
Rembrandt Q. Einstein wrote:


So, would I be correct in assuming that the FM output of the transmitter
is generated directly from the digital distribution signal, without
passing through a DAC first?


No - the FM transmitter is an analogue device so the NICAM distribution
system will have a DAC at it.


For all the national services, the programme chain at the transmitter
site is:
Energis fibre or Microwave link feed, 8.448Mb/sec
Demultiplers down to 4x 2048 kbit/sec
"RE" electronics NICAM decoder, each national service has a bitrate of
676Kbit/sec for the stereo pair.
Nicam decoders provide L+R analogue output.
Several metres of balanced lines from the NICAM bay to the "Transmitter
Input Equipment bay"
SBS Electronics "MPX5" stereo coder. RDS data is added at this point.
TM4 series RF drive where the Frequency Modulation is applied.
High power amplifier.

Frank.



Who makes those TM4 series drives Frank?..
TM4/2 and TM4/6 are BBC design (Now obsolete), probably manufactured
under licence by Eddystone Radio. They are crystal controlled,
frequency modulation is applied to a low frequency oscillator which is
mixed with the crystal oscillator. A frequency control loop stabilises
the final output frequency. This has a time constant of around 30
seconds so as not to affect the modulation.

Frank

Dave Plowman wrote in message ...
In article ,
Rembrandt Q. Einstein wrote:
It says more that people really don't understand figures - or more that
they can't relate to what they sound like.

Quite, although the DAB prospect is rather worrying. This is interesting:

http://www.whathifi.com/newsMainTemp...=2&storyID=109

I won't be dumping my Sansui TU-710 yet, especially since it only cost
me £20.

Thing is that all the pop stations on FM are heavily processed. As are AM.
DAB at the current bitrate seems quite capable of equalling the former and
beating the latter, quality wise.

Those stations that one would wish good quality from, like say R2,3 and 4
- and say Classic and Jazz FM - should have a higher bitrate. And no
processing.

However, all the powers that be have decided processing of some sort is
necessary on virtually all stations on all media - it's apparently what
the public want. So it's no surprise that they also want to reduce the
bitrate on DAB to the point where it's audible.

One would hope that in time the desire for higher sound quality will
triumph, but I won't be holding my breath!

This is interesting, and by a DAB proponent too:

http://www.digitalradiotech.co.uk/ofcom_article.pdf

Jim Lesurf wrote:
In article , Rembrandt
Q.

However, does anyone have any information that pertains to my
original query, about the Radio 3 broadcast chain, and specifically
what CD players/DACS do they use and is there any compression?

Don't know what players they use. However I would suspect that they
take the digital output, process that digitally, and then convert
that directly into the 'NICAM' digital signal for sending to the
transmitter chain. This will presumably then be decoded by
broadcast-equipment DACs for FM transmission.

I don't think there's any need for DAC at that stage: some FM exciters
are digital and take an AES3 signal directly.

Andrew.

Jim Lesurf wrote:
In article , Rembrandt
Q.

However, does anyone have any information that pertains to my
original query, about the Radio 3 broadcast chain, and specifically
what CD players/DACS do they use and is there any compression?

Don't know what players they use. However I would suspect that they
take the digital output, process that digitally, and then convert
that directly into the 'NICAM' digital signal for sending to the
transmitter chain. This will presumably then be decoded by
broadcast-equipment DACs for FM transmission.

I don't think there's any need for DAC at that stage: some FM exciters
are digital and take an AES3 signal directly.

Andrew.