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Old 23-04-2019, 13:40   #1
PhilipOneL
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Join Date: Oct 2014
Location: Eastern Newfoundland
Posts: 202
Audio quality: WINB and V Nigeria both on 15120 kHz; 19/4/19 and 22/4/19

I was in a fairly low-QRM area of Trinity Bay, about 50 km NW of my home in St. John's, Newfoundland, for a few days.

I had a chance on Friday to record a few minutes of the DRM from Voice of Nigeria on 15120 kHz. It was received nearly flawlessly (100% decoding for most of the hour I was tuned) on my MorphyRichards 27024, mostly with its built-in whip and no assistance from my 8m wire aerial. A minute or so can be heard here: http://www.ipernity.com/doc/justfolk/48517724
The mode was, according to my radio c / 10 kHz with 16 QAM in both SDC and MSC, making 9020 bps audio.

On Monday, I saw that WINB was present on that same frequency and, although reception was very choppy (and this time with the assistance of the 8m wire), I recorded a minute or so. It can be heard here: http://www.ipernity.com/doc/justfolk/48517726
The mode was b / 5 kHz with 4 QAM in SDC and 64 QAM in MSC, with a total of 8280 bps.

To my ear, the audio is better from WINB. Nonetheless, the notion of "near-FM-quality" continues to elude me. I certainly do not hear anything approaching FM quality of speech in the DRM I hear from any station. Clearly, though, there are big differences in the quality of audio being fed to the transmitters. I don't understand why poor audio is being fed.

[By the way, both recordings were made on an SD disk in the MorphyRichards, and then played back into an mp3 recorder by line connection. Each mp3 recording was very slightly EQ'd (in SoundForge), primarily to bring the levels up in the Nigeria recording as its mp3 was accidentally recorded with somewhat lower volume.]
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Old 23-04-2019, 18:39   #2
tpreitzel
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The DRM Consortium really needs to stop using the "near FM" quality label for SW broadcasts. For MW DRM broadcasts, the consortium probably uses the label to equate the lack of noise with "near FM" quality. Although the consortium's approach is rather simplistic, it's probably suitable as a marketing ploy. LoL

Yes, the poor quality of broadcasters' feeds is the main problem with digital AM, just like analog AM. Basically, broadcasters are lazy and don't care enough about their signals to monitor them for quality. Should we, as potential listeners, care enough about such broadcasters to listen to them?
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Old 24-04-2019, 13:07   #3
PhilipOneL
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Damn good question.
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