Serge Auckland wrote:
"Robert" wrote in message
oups.com...
On Mar 6, 3:36 pm, (Robin Fairbairns) wrote:
"Brian Gregory [UK]" writes:

"alexander.keys1" wrote...
Last night I was round at a friend's, and they wanted to listen
to BBC Radio 3, on their portable DAB. However it did not show up
on the list of channels, although the other BBC channels were
working. I tried rescanning it, but R3 is still missing.

This is in Leicester, presumably from the same Tx that I reported
recently wasn't providing a usable signal at my location (just
tried my DAB for the first time in weeks - BBC is now back on,
including R3 ).

So what could be causing the above problem?

Crap buggy firmware in the receiver?

we moved into the kitchen to eat our evening meal, and switched on
the (modest) digital there. it played for a few minutes, and then
started breaking up. at the point where there was more silence
than signal, i switched the digital off and we gave up.

this was in cambridge: i don't know which tx serves us (presumably
not the tiny repeater just over our horizon that gives us such poor
fm service ... after all, with digital i get stereo reception ...
when i can receive it at all).
--
Robin Fairbairns, Cambridge

You don't get full stereo on radio 3 any more. They now usually
broadcast in "joint stereo" which gives a poor stereo image but
lower distortion. For full stereo and good sound quality you
really need to stay with FM.

Robert
Cambridge


Strange you say this, as joint stereo is very similar in concept to
multiplex stereo on FM. In joint stereo, the stereo sum and
difference are coded separately, and in FM, L+R and L-R are
transmitted seperately and in both cases reconsituted in the
receiver. Also in both cases the L-R channel carries less information
than the L+R channel. I would therefore have thought that in terms of
stereo, both FM and DAB would have been very similar.


You're confusing different kinds of joint stereo. DAB uses 'intensity
stereo' joint stereo, whereas the kind of joint stereo you're referring to
is mid/side (used on FM, and used by MP3, AAC, WMA etc, but not by MP2,
which is used on DAB). Intensity stereo is lossy, whereas mid/side is
lossless.

Intensity stereo used on DAB forms L+R, encodes that and also encodes the
ratio of the energy in the L to energy in the R channel. Therefore, the
signal envelope is destroyed. Bye bye information, bye bye phase, hello
pan-potted mono.

Welcome to the wonderful world of DAB, the future of radio designed in the
1980s.



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

Find the cheapest Freeview & DAB prices:
http://www.digitalradiotech.co.uk/fr..._receivers.php
http://www.digitalradiotech.co.uk/dab/dab_radios.php

"DAB sounds worse than FM" dab.is@dead wrote in message
...
Serge Auckland wrote:
"Robert" wrote in message
oups.com...
On Mar 6, 3:36 pm, (Robin Fairbairns) wrote:
"Brian Gregory [UK]" writes:

"alexander.keys1" wrote...
Last night I was round at a friend's, and they wanted to listen
to BBC Radio 3, on their portable DAB. However it did not show up
on the list of channels, although the other BBC channels were
working. I tried rescanning it, but R3 is still missing.

This is in Leicester, presumably from the same Tx that I reported
recently wasn't providing a usable signal at my location (just
tried my DAB for the first time in weeks - BBC is now back on,
including R3 ).

So what could be causing the above problem?

Crap buggy firmware in the receiver?

we moved into the kitchen to eat our evening meal, and switched on
the (modest) digital there. it played for a few minutes, and then
started breaking up. at the point where there was more silence
than signal, i switched the digital off and we gave up.

this was in cambridge: i don't know which tx serves us (presumably
not the tiny repeater just over our horizon that gives us such poor
fm service ... after all, with digital i get stereo reception ...
when i can receive it at all).
--
Robin Fairbairns, Cambridge

You don't get full stereo on radio 3 any more. They now usually
broadcast in "joint stereo" which gives a poor stereo image but
lower distortion. For full stereo and good sound quality you
really need to stay with FM.

Robert
Cambridge


Strange you say this, as joint stereo is very similar in concept to
multiplex stereo on FM. In joint stereo, the stereo sum and
difference are coded separately, and in FM, L+R and L-R are
transmitted seperately and in both cases reconsituted in the
receiver. Also in both cases the L-R channel carries less information
than the L+R channel. I would therefore have thought that in terms of
stereo, both FM and DAB would have been very similar.


You're confusing different kinds of joint stereo. DAB uses 'intensity
stereo' joint stereo, whereas the kind of joint stereo you're referring to
is mid/side (used on FM, and used by MP3, AAC, WMA etc, but not by MP2,
which is used on DAB). Intensity stereo is lossy, whereas mid/side is
lossless.

Intensity stereo used on DAB forms L+R, encodes that and also encodes the
ratio of the energy in the L to energy in the R channel. Therefore, the
signal envelope is destroyed. Bye bye information, bye bye phase, hello
pan-potted mono.

Welcome to the wonderful world of DAB, the future of radio designed in the
1980s.



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

Find the cheapest Freeview & DAB prices:
http://www.digitalradiotech.co.uk/fr..._receivers.php
http://www.digitalradiotech.co.uk/dab/dab_radios.php

Thanks for that. I was unaware that joint stereo on MP2 was different to MP3
etc.

S.