Problem receiving Classic DAB+

[Woody]

Can anyone explain why the radio on the end of my desk receives Jazz FM,
Gold, Virgin Anthems and the like all of which seem to be 32K DAB+ but
when I tune to Classic all I get is a data noise (buzzing)? I admit the
signal is not strong but it worked perfectly well on ordinary DAB but it
won't work on DAB+.

Er, help?

[Mark Carver]

Interesting. It may not be compatible with AAC V1 (the other DAB+
stations are AAC V2) What model radio is it ?

[Scott]

On Fri, 5 Jan 2024 13:37:51 +0000, Mark Carver <ma...@invalid.com>
wrote:

Could you clarify the difference for those of us who do not know? I
have found this sentence: 'HE-AAC v2 is optimized for even more
aggressive compression than HE-AAC by adding Parametric Stereo (PS) to
HE-AAC'. Does this mean Classic is using less compression (because
it's classical music)? What does optimised mean in this context - that
compression is needed for best results or the broadcaster is free to
choose but v2 will sound better than v1? after compression?

Is Radio 3 still uncompressed (on DAB)?

[John Williamson]

On 05/01/2024 13:51, Scott wrote:

> Could you clarify the difference for those of us who do not know? I
> have found this sentence: 'HE-AAC v2 is optimized for even more
> aggressive compression than HE-AAC by adding Parametric Stereo (PS) to
> HE-AAC'. Does this mean Classic is using less compression (because
> it's classical music)? What does optimised mean in this context - that
> compression is needed for best results or the broadcaster is free to
> choose but v2 will sound better than v1? after compression?
>

AACv2 was first standardised in 2006, so older radios may not support
the codec.

Full history is here:-

https://en.wikipedia.org/wiki/Advanced_Audio_Coding

> Is Radio 3 still uncompressed (on DAB)?
>

*All* digitally broadcast audio (And video, but that's a different set
of problems)is digitally compressed, using a lossy compression scheme.
Most is also transmitted using dynamic range reduction techniques before
the encoder and multiplexers get to see it. The only variable is how it
is compressed. (MP2 or AAC, and the bitrate used) Uncompressed 16 bit
audio (CD quality, 44.1 kHz sample rate) has a bit rate of 1,411 kbps as
against the normal 64 kbps for reasonable quality music stations

Radio 3 tends to use less analogue dynamic range compression than other
stations, and also uses a higher bit rate most of the time.


--
Tciao for Now!

John.

[Andy Burns]

Scott wrote:

> Mark Carver wrote:
>
>> Interesting. It may not be compatible with AAC V1 (the other DAB+
>> stations are AAC V2) What model radio is it ?
>
> Could you clarify the difference for those of us who do not know? I
> have found this sentence: 'HE-AAC v2 is optimized for even more
> aggressive compression than HE-AAC by adding Parametric Stereo (PS) to
> HE-AAC'. Does this mean Classic is using less compression (because
> it's classical music)?

That was my take-away from the wiki article Mark linked previously
<https://en.wikipedia.org/wiki/High-Efficiency_Advanced_Audio_Coding>

That said a less capable decoder ought to play with a treble-cut, so the
implication there's a graceful fallback from LC+SBR+PS to LC+SBR to LC
with the result being audible, rather than just noise like Woody is getting?

> What does optimised mean in this context - that
> compression is needed for best results or the broadcaster is free to
> choose but v2 will sound better than v1? after compression?
>
> Is Radio 3 still uncompressed (on DAB)?

MP2 is compressed, just less compressed
<https://en.wikipedia.org/wiki/MPEG-1#Layer_II>

[Andy Burns]

Woody wrote:

> Can anyone explain why the radio on the end of my desk receives Jazz FM,
> Gold, Virgin Anthems and the like

At least JazzFM and Virgin Anthems are on SDL mux, whereas ClassicFM is
on D1 mux, are other D1 channels ok? Gold probably not a good test as
it varies which mux it's on throughout the country?

[Woody]

SondStrom (Curry's?) S6VDAB12

[Woody]

On Fri 05/01/2024 14:24, John Williamson wrote:
> On 05/01/2024 13:51, Scott wrote:
>
>> Could you clarify the difference for those of us who do not know?  I
>> have found this sentence: 'HE-AAC v2 is optimized for even more
>> aggressive compression than HE-AAC by adding Parametric Stereo (PS) to
>> HE-AAC'.  Does this mean Classic is using less compression (because
>> it's classical music)? What does optimised mean in this context - that
>> compression is needed for best results or the broadcaster is free to
>> choose but v2 will sound better than v1? after compression?
>>
> AACv2 was first standardised in 2006, so older radios may not support
> the codec.
>
> Full history is here:-
>
> https://en.wikipedia.org/wiki/Advanced_Audio_Coding
>

[snip]

Can't tell but the serial number starts 1527 so wk27 2015?

[Woody]

Curiously I have moved the radio about a foot further into the room and
turned it 45deg and bingo, solid signal.

Baffles me!

[John Williamson]

On 05/01/2024 19:37, Woody wrote:

> Curiously I have moved the radio about a foot further into the room and
> turned it 45deg and bingo, solid signal.
>
> Baffles me!

A digital cliff. The error correction can now cope with the errors.

[Andy Burns]

Woody wrote:

> Curiously I have moved the radio about a foot further into the room and
> turned it 45deg and bingo, solid signal.

So, you're saying DAB gives bubblingmud, but DAB+ gives buzzingmud?

[Scott]

On Fri, 5 Jan 2024 14:47:23 +0000, Andy Burns <use...@andyburns.uk>
wrote:

I thought Gold was on Digital One nationally (with an additional
stream for London).

[Brian Gaff]

Has to be something to do with the site of the transmitter, whether there
are multipaths or the errors that the chipset can cope with My Roberts seems
to cope here but then all the transmitters are line of site.
I do honestly wish they had actually decided on the system to use before
all the early models of radio were made with hardware decoding. It has
resulted an a lot of early car radios and many Pure models from the past
being unable to be made to work on plus of any kind, although the data for
the display works.
Brian

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[Brian Gregory]

Weird. The error detection and correction on DAB+ is normally very
robust and, in my experience, it's rare to hear anything other than
silence or perfect reception (or flipping slowly between the two).

--
Brian Gregory (in England).