Talk:Digital Radio Mondiale

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Contents

[edit] Criticism

Should add a section. From the reading I've done, the DRM signal becomes totally unreadable at a time when a comparably distorted analog signal is still audible and listenable. It appears to be an unreliable format compared with analog. Also, as SW is still primarily used to disseminate information in the third world, DRM will not be used in areas where the cost of the technology is too high. A $250 radio for every family in Africa and India? I think not. Broadcasters will continue transmitting in analog, so they can be picked up by the millions of listeners with $5 analog radios.

DRM sounds like a much better idea for medium-wave AM, which broadcasts locally and won't suffer the signal degradation, but for international SW broadcasts it's so unreliable as to be useless.71.205.209.100 21:19, 21 August 2007 (UTC)

[edit] Ofcom and UK adoption

I haven't found a referencable link as yet, but I got it in a work newsletter. Ofcom is seriously considering not renewing Virgin and TalkSports' AM licenses so that they can reuse the AM bandwidth for DRM. - David Gerard 09:24, 27 September 2006 (UTC)

[edit] Low bitrate

The given bitrates of "8 kbit/s to 20 kbit/s" seem extraordinarily low compared with the ~128kbits/s typical minimum for reasonable AAC. Can someone explain this in the article? Is there a byte/bit error? Hotlorp 13:03, 7 December 2006 (UTC)

Actually it's AAC+ (or HE-AAC) which sounds good at only half the bitrate of MP3. I routinely listen to a 24 kbit/sec AAC+ station via internet streaming, and it sounds just as good as FM (i.e. nowhere near CD quality, but still a lot better than AM). Plus if you read the wiki article on this subject it states, "Further controlled testing by 3GPP during their revision 6 specification process indicates that HE-AAC and its derivative MPEG-4 HE-AAC v2 provide "Good" audio quality for music at low bit rates (e.g. 24 kb/s)."
Also the bitrate is comparable to what AM-HD Radio does with 10 kilohertz space (20 kbps), so I don't think there's an error there. Let's face it; you can't squeeze a lot of data into only 10 kilohertz. It's somewhat similar to trying to squeeze data through an 8 kilohertz-wide phone line. Recall that dialup is limited to ~50 kbps, and only if the line is perfectly clean. - Theaveng 22:16, 25 September 2007 (UTC)

[edit] Removal of comparison with HD-Radio

I had several reasons why I removed the following statement:

For comparison, pure digital HD Radio can broadcast 40 kbit/s using 10 kHz width and 60 kbit/s using extended bandwidth.

  • It compared audio bit rates for DRM with link bit rates for HD-Radio
  • HD-Radio uses channels 20kHz wide in all-digital mode for rates ~40 or ~60kbit/s (depending on robustness) and 30kHz wide channels in hybrid (analog+digital) mode for rates ~37 or ~57kbit/s (again depending on robustness). See The Structure and Generation of Robust Waveforms for AM In-Band On-Channel Digital Broadcasting [PDF, pp.6-8, 242KB].
  • Link rates for DRM on the other hand are provided only for channels 9kHz (max.~31kbit/s) and 10kHz (max 27.4kbit/s) wide
  • Unfortunately the same misinformation is provided on HD-Radio page in section AM-HD vs. AM-DRM as well

24.81.130.107 09:14, 28 September 2007 (UTC)

I reviewed the white papers, and it turns out you were at least partly correct. Thanks for point it out. HD-Radio does fit into a 10 kilohertz channel, but that mode is limited to only 20 kbit/s. I've made the fix in the article. (Why was it necessary to delete the whole sentence????) (All you need to do was fix the mistake, not delete everything.)
As for DRM, I don't see any citations to support your "27.4 kbps assertion. Can you please provide some? Thank you. - Theaveng 10:09, 28 September 2007 (UTC)
You are right. It's not 27.4kbps. It's 34.8kbps :-) [PDF, 4.5MB, pp.19]. I should probably also mention that the maximum achievable speed is 72kbps for mode A, bandwidth 20kHz and lowest robustness level. 24.81.130.107 12:27, 28 September 2007 (UTC)
Ya know, I just scanned that whole PDF document, and I see nothing to support your assertion. Please provide specific page numbers or Table/Figure numbers. Thank you. - Theaveng 13:59, 28 September 2007 (UTC) ---------- UPDATE - Never mind; in the article you told everyone it was on page 19. So let's see if I understand how this system would work for a U.S. application (10 kilohertz) using kbits/second and 64-QAM:
  • 5 khz == 16 (day), 13 (night), 8 (maximum robustness)
  • 10 kHz == 34 (day), 27 (night), 17 (maximum robustness)
  • 20 kHz == 72 (day), 56 (night), 31 (maximum robustness)
And for 16-QAM:
  • 5 khz == 8 (day), 6 (night), 5 (maximum robustness)
  • 10 kHz == 18 (day), 14 (night), 11 (maximum robustness)
  • 20 kHz == 38 (day), 29 (night), 23 (maximum robustness)
Now, how am I going to put that confusing mess into the HD Radio comparison, in such a way that the average Joe Smith can understand it. Hmmm. - Theaveng 14:12, 28 September 2007 (UTC)
QUESTION 1: Do most DRM broadcasters use 64-QAM or 16-QAM? Thanks.
QUESTION 2: Do most DRM broadcasters use 64-QAM or 16-QAM? Thanks. - Theaveng 14:40, 28 September 2007 (UTC)

[edit] OFDM system comparison table

Feel free to add a DRM column to the OFDM#OFDM system comparison table. Mange01 11:48, 17 July 2007 (UTC)

[edit] Broken Link under DRM in General section

The link for "A Listeners' Guide to Digital AM (DRM)" gives me an error 404.

216.230.101.253 19:10, 15 August 2007 (UTC)

Fixed.

24.81.130.107 09:25, 28 September 2007 (UTC)