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Old 10-02-2018, 19:24   #61
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Join Date: Apr 2012
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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!


Last edited by tpreitzel : 10-02-2018 at 20:12.
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Old 10-02-2018, 19:25   #62
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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.



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 19:45.
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