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Topic: DAB sound quality and antenna signal strength. (Read 4576 times) previous topic - next topic
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DAB sound quality and antenna signal strength.

I have just bought a Cambridge audio DAB/FM tuner.
First I just hang the small antenna behind my stereorack and the sound of DAB was not good. I heard digital artifacts in the background. Now I have put my antenna outdoors and got about twice the signalstrenght that I had with the antenna indoor. And now I think DAB sounds much better.
Anyone else here with any experiences about DAB listening?
Btw. I live in Norway.

Snire
Once I used Maxell XLIIs, now I use cdr.

DAB sound quality and antenna signal strength.

Reply #1 –
Does DAB really "gracefully" degrade? I didn't know the MPEG2 it used was scalable, would have expected dropouts instead.

DAB sound quality and antenna signal strength.

Reply #2 –
Apperantly it does. Atleast it has a gracefull area before cutting out.
Some describe it as a gurgling effect in the background.
I read in a DAB paper somewhere this gracefull property was one of the reason they chose musicam (mpg layer 2).
Today you could slap  a 1/2 rate Forward Error Correction on there with  AAC or Vorbis and still beat the crap out current DAB implementations with respect to both range and audio quality.

DAB sound quality and antenna signal strength.

Reply #3 –
They call that Digital Radio Mondiale

You can receive it with a shortwave radio and a PC decoder.

DAB sound quality and antenna signal strength.

Reply #4 –
Quote
Does DAB really "gracefully" degrade? I didn't know the MPEG2 it used was scalable, would have expected dropouts instead.
[{POST_SNAPBACK}][/a]


It's hardly graceful. It's just that some types of music mask it a little.

If you're listening to something critical for hearing this burbling and gargling, (or blips and bleeps), then it can be quite obvious. e.g. classical music (especially single instruments or singers) vs typical pop music.

How is DAB in Norway? In the UK it sounds awful!

Oh, just found this...
[a href="http://www.wohnort.demon.co.uk/DAB/h-t.html#Norway]http://www.wohnort.demon.co.uk/DAB/h-t.html#Norway[/url]

We seem to have many more stations than you, and slightly poorer quality. Does Norway really only have 2 DAB muxes allocated to it? I think we have 7, though not all are in use everywhere. You can get about 50 low quality stations on DAB in London, many mono only.

Do the stations in Norway sound like CD quality, or lower?

Cheers,
David.

DAB sound quality and antenna signal strength.

Reply #5 –
DRM is a good idea, however the 16-28kbit/s isn't enough for my ears even with HE-AAC PS.
If they can break the traditional 9khz bandwidth channel  raster and make 64kbit version however, then it would be real nice.
Cover a whole country with just one transmitter.
Portable units might have trouble with the antenna size, but I read somewhere about somebody making new types of ferrite to shrink AM antennas and still have good efficiency.

DAB sound quality and antenna signal strength.

Reply #6 –
DRM supports double channel modes, so you could get up to 48kbps for example.

I find PS-AAC at 20kbps very listenable, though.

DAB sound quality and antenna signal strength.

Reply #7 –
Weren't the DRM folk working on an FM spec that's supposed to be better? It doesn't need that many more kbits to beat FM.

Another thing: How well can mp2, and therefore DAB, theoretically perform? I recall reading a rumor that there might be mp2 compatible output streams from the musepack decoder in the future, how much worse will this be compared to mpc?
It also hasn't seen the amount of development effort MP3 had (through LAME), has it?
Veni Vidi Vorbis.

DAB sound quality and antenna signal strength.

Reply #8 –
Quote
Quote
Does DAB really "gracefully" degrade? I didn't know the MPEG2 it used was scalable, would have expected dropouts instead.
[{POST_SNAPBACK}][/a]


It's hardly graceful. It's just that some types of music mask it a little.

If you're listening to something critical for hearing this burbling and gargling, (or blips and bleeps), then it can be quite obvious. e.g. classical music (especially single instruments or singers) vs typical pop music.

How is DAB in Norway? In the UK it sounds awful!

Oh, just found this...
[a href="http://www.wohnort.demon.co.uk/DAB/h-t.html#Norway]http://www.wohnort.demon.co.uk/DAB/h-t.html#Norway[/url]

We seem to have many more stations than you, and slightly poorer quality. Does Norway really only have 2 DAB muxes allocated to it? I think we have 7, though not all are in use everywhere. You can get about 50 low quality stations on DAB in London, many mono only.

Do the stations in Norway sound like CD quality, or lower?

Cheers,
David.
[a href="index.php?act=findpost&pid=314304"][{POST_SNAPBACK}][/a]


I think DAB here in norway is not good enough on hifi equipment, (listening to conserts etc). But good enoguh for daily radio listening.
NRK Always classic is the best I think with 192 kbps. Edit: 160 kbps
My father listen much to this channel, and he is very pleased with the sound quality. He uses a Cambridge audio DAB/FM tuner, Harman Kardon amp. and B&W loudspeakers.
DAB in Norway is lower quality than CD in my ears.
But for now we have only 7stations I think +2 night channels
Once I used Maxell XLIIs, now I use cdr.

DAB sound quality and antenna signal strength.

Reply #9 –
DRM is being extended up to 120MHz, but they're proceeding slowly - ironically, the DRM consortium don't want to get the DAB people scared because they need their co-oporation. The same companies are likely to make chipsets for both. If extended thoughtfully, DRM could trash DAB, but is unlikely to be allowed to.

Frank mentioned the Musepack encoder outputting mp2. He suggested it worked well, but much worse than native Musepack at comparable average bitrates. Remember mp2 is CBR and has no bitrate reservoir, which cripples performance compared with MusePack itself.

I don't think there's any chance of getting CD quality sound out of 128kbps joint stereo mp2 (which is what most UK stations use), whatever you use to encode it.

Of course, at 256kbps as originally proposed, DAB and mp2 would be fine, if inefficient compared to modern codecs.

The real problem is the attitude of the broadcasters - whatever codec you give them, what's to stop them using at a bitrate which gives mediocre results? In the UK, technical quality used to be regulated to ensure even commercial broadcasters delivered high quality (while the BBC regulated themselves). Unfortunately even the regulator is proposing to lower bitrates now, and the BBC is already one of the worst offenders on DAB, though their commercial rivals sound worse because of processing and transcoding.

Cheers,
David.