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Old 10-02-2018, 18:24   #61
tpreitzel
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Alokesh,

Thanks for posting this news. I especially like the promotion of the non-audio aspects of DRM as this aspect is precisely the component that has the most potential for informing the "listener". I, too, would like to see DIVEEMO both standardized and promoted.

Now, if AIR would only restart DRM broadcasting on shortwave with 16 QAM modulation and the xHE-AAC codec from their transmitter in Bangalore!

http://alokeshgupta.blogspot.com/201...ed-at-bes.html

Last edited by tpreitzel : 10-02-2018 at 19:12.
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Old 10-02-2018, 18:25   #62
tpreitzel
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Quote:
Originally Posted by Aetheradio
The main problem with DRM is nobody can buy or build a receiver that complies fully with the current standard.
It must have both DRM30 and DRM+
It must have all codecs and rates including xHEAAC

The modulation doesnt matter much between 64QUAM and 16QUAM on shortwave. I did enough practical on air tests to show there was maybe a half dB in it. Once your reception gets in the noise below minimum thats it. When things are this bad, only AM works.
The BBC tests on MW went to lower constellation at night due to adjacent channel interference. This is no longer a problem on SW because most everybody has left.

Ralph

Ralph,

Logs on this forum and the experience of other members including myself clearly demonstrate otherwise. The threshold for decoding 16 QAM is MUCH lower at the receiver than 64 QAM even on the MW band. I should know as I have tested it with my DRMAX-1 transmitter. Furthermore, I don't have access to your tests so I can't and won't comment on them specifically. Regardless, ANY lowering of the threshold for decoding a DRM signal on shortwave is an improvement so, again, the use of 16 QAM on shortwave is absolutely necessary to MAXIMIZE decoding for the listener and supported by the thousands of logs on this forum. Therefore, we'll have to agree to disagree.

The inclusion of other codecs isn't really necessary in the DRM standard as xHE-AAC finally realized DRM's potential on shortwave when used in conjunction with 16 QAM ONLY modulation. Opus might be nice, but it certainly isn't necessary now with the advent of xHE-AAC.

As far as including DRM+ capability in receivers, it's not really necessary either, but would probably improve the market for a DRM receiver.

In conclusion, I'll agree partly with your comments that shortwave listening is currently declining because of both ignorance and convenience. Both of these latter factors can and will likely be overcome when more desperate times arise for an individual or even country ... Life isn't always rosy or cozy.

Last edited by tpreitzel : 10-02-2018 at 18:45.
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Old 23-04-2018, 02:30   #63
tpreitzel
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"Old" Analog Concept of Targeting Nations

With the multiple service capability of DRM, the old analog idea of narrowly targeting nations should be dying, but won't until those analog broadcasters die as well unfortunately. It's an awful thought, but apparently true. Engineers are so conditioned by ideology and practice, it'll be difficult to change the situation until new engineers arrive on the SW scene along with further refinements in low bit-rate compression. This latter process is already occurring, but will require more time. I'm NOT saying there will NEVER be a need to target a nation, but that the general practice will decline as multiple service capability is properly employed.

Even with 16 QAM modulation, the current DRM xHE-AAC codec can readily accommodate multiple audio streams and languages with decent quality. Even now, the perceived need for narrowly targeting nations via shortwave is rapidly disappearing and SW broadcast engineers need to rethink their old habits.

Last edited by tpreitzel : 23-04-2018 at 19:16.
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Old 21-06-2018, 15:42   #64
tpreitzel
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If it's possible, the DRM standard will soon have to incorporate 4 QAM modulation into the standard which will be a boon for digital shortwave. Then, digital shortwave broadcasters should be restricted to either 4 or 16 QAM modulation. The continuing research of incorporating AI techniques into codecs will allow audio from ultra low bit-rates below 3 kbps. Essentially, we're already there. Dolby has purchased Coding Technologies and released AC4. Opus will be following the others into the lower end a la Codec2 and its variants. All of this research will be a boon for digital shortwave and its listeners.
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Old 28-06-2018, 00:28   #65
tpreitzel
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Video ports, e.g. HDMI, should be a standard component on digital radios as well as COMPACT IR remote controls on desktop units. When I'm working on various tasks, I don't want to have to stop and twiddle knobs or walk to a radio with a small screen to read data. An HDMI port will allow me to connect a micro projector. Although radio on VHF, HF, and MW bands will probably always remain a primarily audible experience, I can definitely foresee visual data increasing its share of that experience. Hence, designers and manufacturers need to prepare now. Radio data is primarily an attachment to an old analog paradigm. Purely digital technologies like HD, DRM, and DAB haven't been properly deployed since their inception. Again, the old analog paradigm has been replaced so stop thinking within the boundaries of its mental cage.

User-friendly digital radio is flexible and anonymous which are the main reasons for my continued involvement with DRM.

Last edited by tpreitzel : 29-06-2018 at 18:11.
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