Problems with BBC R3 sound via DTTV

If anyone here gets a chance, have a listen to BBC R3 via your DTTV
receiver during the prom rebroadcast this afternoon. May be too late by the
time you read this, but I have been listeing and am finding the sound quite
awful. [1]Yet other BBC radio stations on the same mux seem fine, and the
UHF carrier level here seems OK...

Who does one contact at the BBC these days for reports/complaints about
technical matters like this?

Slainte,

Jim



[1] Effect something like dire levels of flutter multipath distortion on
*AM*. Makes massed strings sound more like a band of balalaikas!

--
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:
If anyone here gets a chance, have a listen to BBC R3 via your DTTV
receiver during the prom rebroadcast this afternoon. May be too late by the
time you read this, but I have been listeing and am finding the sound quite
awful. [1]Yet other BBC radio stations on the same mux seem fine, and the
UHF carrier level here seems OK...

Who does one contact at the BBC these days for reports/complaints about
technical matters like this?

See these threads...

http://groups.google.co.uk/group/alt...59ffea52?tvc=1

http://groups.google.co.uk/group/alt...cb0378c8?tvc=1

I haven't tried R3 recently. I've been recording some Proms from BBC
Four but haven't had chance to listen yet!

As you'll see from the first thread, I tried emailing BBC reception
advice. They were aware of the problem, but could give no indication of
when it might be fixed. It didn't sound like a priority, unfortunately.

Cheers,
David.

All sound on DTT is mp3 format, which employs psycho-acoustic "tricks"
for bit rate reduction, yes it can sound awful.

Might be better to use fm sound and DTT picture, although then they're
not syncronised.

Sometimes, technicians put limiters, noise gates, etc, into sound
channel, which can muck things up even further.

Jim Lesurf wrote:
If anyone here gets a chance, have a listen to BBC R3 via your DTTV
receiver during the prom rebroadcast this afternoon. May be too late
by the time you read this, but I have been listeing and am finding
the sound quite awful. [1]Yet other BBC radio stations on the same
mux seem fine, and the UHF carrier level here seems OK...

Who does one contact at the BBC these days for reports/complaints
about technical matters like this?


. Be prepared for a very, very long wait before they
bother to sort it out.


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

Find the cheapest Freeview, DAB & MP3 Player Prices:
http://www.digitalradiotech.co.uk/fr..._receivers.htm
http://www.digitalradiotech.co.uk/da...tal_radios.htm
http://www.digitalradiotech.co.uk/mp...rs_1GB-5GB.htm
http://www.digitalradiotech.co.uk/mp...e_capacity.htm

"Jim Lesurf" wrote in message
...
If anyone here gets a chance, have a listen to BBC R3 via your DTTV
receiver during the prom rebroadcast this afternoon. May be too late by
the
time you read this, but I have been listeing and am finding the sound
quite
awful. [1]Yet other BBC radio stations on the same mux seem fine, and the
UHF carrier level here seems OK...

Who does one contact at the BBC these days for reports/complaints about
technical matters like this?

Slainte,

Jim



[1] Effect something like dire levels of flutter multipath distortion on
*AM*. Makes massed strings sound more like a band of balalaikas!

--
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


I heard it too - not distortion just a straightforward fault.

In article . com,
wrote:
Jim Lesurf wrote:
If anyone here gets a chance, have a listen to BBC R3 via your DTTV
receiver during the prom rebroadcast this afternoon. May be too late
by the time you read this,

[snip]

http://groups.google.co.uk/group/alt...59ffea52?tvc=1

http://groups.google.co.uk/group/alt...cb0378c8?tvc=1

I haven't tried R3 recently. I've been recording some Proms from BBC
Four but haven't had chance to listen yet!

Thanks for the above urls. They make interesting reading in this context.

FWIW I stopped listening/recording a little after 3pm, and then wrote
postings to here and uk.rec.audio about the effect. I also emailed
'feedback' asking them to pass on my experience and related questions to
someone who might answer. (Always the optimist! ;- )

By the time I tried listening again at about 3:35pm the problem had abated.

I was listening on FM up until about 2:45pm, and that had sounded fine. I
switched on the DTTV RX then, and immediately noticed the problem. It was
so bad I even did a power-down cycle of my RX to ensure it was OK.

I had been intending to record the entire 'Sea Symphony' onto DVD-R as that
is connected to the DTTV RX. I'm collecting comparison recordings for doing
an analysis at a later date. With some of the previous proms I felt I'd
been hearing artefacts/problems on the DTTV R3 rebroadcasts that I wasn't
hearing on the BBCTV 'live' sic broadcasts of the same proms, so have
been 'collecting data' for closer examination in due course.

However I'd *never* heard any BBC transmissions on R3 sound as truly awful
as around 3pm today. I nearly decided to abandon recording altogether, but
after consideration I did do some recording. This means I recorded the
first section of the 'Sea Symphony' via BBC R3 DTTV, and whilst doing so I
used the RX to display the signal level and the channel number. I also
switched to recording BBC R4 for a while to show this *didn't* have the
obvious problem of R3, yet is on the same mux/channel. The advantage of the
DVD recording here is that it shows the details of the signal levels, etc,
as displayed by the DTTV RX.

After about 3:35pm I recorded the last 10 mins or so of the R3 broadcast of
the 'Sea Symphony' and the following announcer speaking. This is on the
same disc as the above - which also has the BBCTV4 version. Hence I have
all the versions on one disc. (I am now hoping the Philips doesn't ruin the
disc when/if I finalise it, so may copy it before that!!)

In due course, I plan to make copies of the sound of this disc, and some
others, onto CD-R via the DVD recorder's s/pdif output. This, alas, means
another 'common mode' 48/44.1 ksamples/sec conversion, but I doubt that
will mask the problem as it is deafeningly obvious! I can then load the
data from the CDR onto the computer I use and do some analysis...

Doing the above as I don't have an algorythm for reading the 'vob' files on
the DVD and extracting the sound in the form of LPCM. The discs are ones
recorded, domestically, with the Philips DVDR70. IIUC these aren't
encrypted with CSS. Is there an algorythm for this someone can point me to?
If I could do that I could recover the data from the DVD's in a form that
avoids another rate-conversion. Also would avoid my having to move the CD
recorder... :-)

As you'll see from the first thread, I tried emailing BBC reception
advice. They were aware of the problem, but could give no indication of
when it might be fixed. It didn't sound like a priority, unfortunately.

What I heard today did not sound like a problem that *any* listeners would
have found acceptable. It wasn't the kind of difference you might associate
with something like '192kb/s versus 256kb/s'. Seemed far more gross. Orders
of magnitude that any defects I've heard before. More like some very
serious fault. In general, I sometimes find that the DTTV R3 can sound OK,
but often shows low-level problems. This was on a completely different
scale!

My suspicion is that something is/was going wrong somewhere along the line.
Maybe the BBC are not even aware that the data they are sending for
broadcast is being trashed somewhere between the BBC and the RX. This
makes me wonder if similar problems are arising at a 'lower level' at other
times...

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

On 2005-07-27, Jim Lesurf wrote:
I had been intending to record the entire 'Sea Symphony' onto DVD-R as that
is connected to the DTTV RX. I'm collecting comparison recordings for doing
an analysis at a later date. With some of the previous proms I felt I'd
been hearing artefacts/problems on the DTTV R3 rebroadcasts that I wasn't
hearing on the BBCTV 'live' sic broadcasts of the same proms, so have
been 'collecting data' for closer examination in due course.

If you like I can send you a 48 ksample/s .wav on CD or DVD of today's
Prom re-broadcast, captured from R3 DAB, which may well be nominally
the same bitstream as R3 DTTV. I haven't listened to it all but the
Mendelssohn sounds fine as do a few random samples from the Bruch and
the V-W.

My suspicion is that something is/was going wrong somewhere along the line.

Probably a R3 DTTV tx chain fault since R3 DAB sounds fine.

--
John Phillips

spiney wrote:
All sound on DTT is mp3 format,

No it's not, it's mp2

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

In article , John Phillips
wrote:
On 2005-07-27, Jim Lesurf wrote:
I had been intending to record the entire 'Sea Symphony' onto DVD-R as
that is connected to the DTTV RX. I'm collecting comparison recordings
for doing an analysis at a later date. With some of the previous proms
I felt I'd been hearing artefacts/problems on the DTTV R3 rebroadcasts
that I wasn't hearing on the BBCTV 'live' sic broadcasts of the same
proms, so have been 'collecting data' for closer examination in due
course.

If you like I can send you a 48 ksample/s .wav on CD or DVD of today's
Prom re-broadcast, captured from R3 DAB, which may well be nominally
the same bitstream as R3 DTTV.

Yes please! :-) ...and many thanks for the battery. :-)

Although isn't DAB at 32 ksamples/sec?...

It will definately be useful to have a copy of the DAB version as I can
then compare that with the DTTV BBCTV4 version, as well as with the
'excerpts' I took from the faulty DTTV R3 version. Either CD or DVD would
be excellent.

I haven't listened to it all but the Mendelssohn sounds fine as do a few
random samples from the Bruch and the V-W.

If the later part of the Bruch and the start of the VW sound fine, then it
seems that it doesn't have the fault that made the DTTV R3 version unbearable.

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

DAB sounds worse than FM wrote:
Jim Lesurf wrote:

If anyone here gets a chance, have a listen to BBC R3 via your DTTV
receiver during the prom rebroadcast this afternoon. May be too late
by the time you read this, but I have been listeing and am finding
the sound quite awful. [1]Yet other BBC radio stations on the same
mux seem fine, and the UHF carrier level here seems OK...

Who does one contact at the BBC these days for reports/complaints
about technical matters like this?



. Be prepared for a very, very long wait before they
bother to sort it out.


There are only a handful of engineers in RA, but most of them read the
newsgroups as do the engineers looking after DTT & DSAT. Mind they are
now Siemens, so there's probably a bill gone into the BBC they want
paying first ;-)