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Old 04-09-2017, 21:58   #46
tpreitzel
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Quote:
Originally Posted by F1BJB
HI
I don't agree that forbidding anything will promote DRM.
On the contrary dynamic changing of modes and frequency according to
target,content and propagation should be promoted.
It will help detecting receivers with too limited features.
Feedback from listeners should allow broadcasters to choose the best mode.
Laurent

Laurent,

Although dynamic changing of modes would be better than any static configuration, thousands of logs have clearly demonstrated that 64 QAM modulation has problems on shortwave bands. Modulation of 64 QAM was clearly intended for AAC+ codecs on the MW band, not HF. Consequently, xHE-AAC was added to the DRM standard primarily for use on HF at LOW bit-rates. Hence, we'll have to agree to disagree on that issue.

Last edited by tpreitzel : 04-09-2017 at 22:18.
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Old 06-09-2017, 22:43   #47
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I was listening to HWN on 7268 kHz (LSB) during the early morning hours last night and the discussion was riveting as I tracked hurricane Irma through the Caribbean just east of Anguilla, home of the Valley SW station. I used the map of the Caribbean in WRTH. Irma was intensifying as it passed near Barbuda. Naturally, the Valley on 6090 kHz was off the air earlier than scheduled. I wonder how the Valley fared this onslaught.

I'm confident that DRM will one day play a major role on the SW bands during disasters such as this unfortunate one. Irma isn't done yet and I'll be listening. Hopefully, one day I'll be reading data via DRM and SW about such events.

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Old 10-09-2017, 21:44   #48
tpreitzel
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Millions of Potentially New Listeners One Disaster Away

The title says it all. Younger generations WILL turn to radio as have PAST generations simply because it works under severe conditions. The infrastructure does NOT fail except for brief periods and always recovers by itself and without cost. Younger generations, even this older generation poster , expect digital capability, not some boring analog broadcaster. DRM will benefit as a result.

The idea that younger generations will ALWAYS ignore OTA broadcasting is both silly and ignorant. Younger generations are just a disaster away from becoming new listeners.

With the aforementioned said, OTA broadcasting will need to become more on-demand, though, with shorter and greater variety. Future DJs will basically be researchers. Both the Spynet and Spyphone can accommodate immediate interaction when desired. Personally, I prefer more secure mail.

Last edited by tpreitzel : 11-09-2017 at 14:14.
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Old 13-11-2017, 00:35   #49
tpreitzel
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DRM has a problem with its image due to poor digital configurations on shortwave for over a decade. The AAC+ codec was fine for the MW band, but has its limitations on shortwave which unfortunately encouraged shortwave broadcasters to use MSCs of 64 QAM. This problem can only be resolved through sane configurations appropriate for shortwave, i.e. MSCs of 16 QAM, and the xHE-AAC codec. Of the current digital broadcasters, only VoN has an appropriate configuration. Although VoN still has room for improvement within the constraint of 16 QAM, it's main issue even at the currently low bit-rate is poor quality of audio from their remotes. The studio production from VoN is acceptable at such a low bit-rate. However, if VoN ever returns to digital shortwave, they should certainly adopt the xHE-AAC codec instead of AAC+.

Hence, the recovery of DRM's tarnished image will take additional some time and persistence unfortunately. It's high time for shortwave broadcasters to get with the program of robust configurations and the xHE-AAC codec.

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Old 13-11-2017, 01:23   #50
zfyoung
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Quote:
This problem can only be resolved through sane configurations appropriate for shortwave, i.e. MSCs of 16 QAM, and the xHE-AAC codec
This is the only short term stopgap solutions to the HF broadcast problem.
Actually the main complaint I have against DRM is that the codec (AAC+/xHE) remains proprietary product. This not only put a hurdle on wider adoption of modern broadcast standard, it also discourage any attempt to improve or it co-opted to better systems. And indeed there is a far better solution to this kludge: why let the broadcaster to dictate the configuration of transmission signals (64/16QAM, bitrate, AAC/xHE etc.) at TX side, why NOT let the receiver to decide that at RX side depending on the local SNR level? This strategy incorporate the agility of analogue system and efficiency of digital system and DX friendly.
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Old 13-11-2017, 21:00   #51
tpreitzel
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Quote:
Originally Posted by zfyoung
This is the only short term stopgap solutions to the HF broadcast problem.
Actually the main complaint I have against DRM is that the codec (AAC+/xHE) remains proprietary product. This not only put a hurdle on wider adoption of modern broadcast standard, it also discourage any attempt to improve or it co-opted to better systems. And indeed there is a far better solution to this kludge: why let the broadcaster to dictate the configuration of transmission signals (64/16QAM, bitrate, AAC/xHE etc.) at TX side, why NOT let the receiver to decide that at RX side depending on the local SNR level? This strategy incorporate the agility of analogue system and efficiency of digital system and DX friendly.


If you're implying that the DRM standard has asymmetric ability, then I was unaware of that capability. As Laurent suggested, dynamic capability certainly would be better than any static configuration, but asymmetric capability is another matter entirely. Explain to me how your scenario would work with the DRM standard both technically and experientially. Keep it simple and, if appropriate, use the DR-111 as the receiver in any example.

Are you suggesting that if a broadcaster used a 64 QAM configuration, then the DRM standard allows for the asymmetic reconfiguration at the receiver to 16 QAM?

Personally, I support the concept of dynamic configuration at the RX, but I think it's best to place the onus on the broadcaster for the foreseeable future. Yes, the BBC still broadcasts automatic frequency changes when no such frequencies exist and most digital broadcasters can't even broadcast time signals correctly, etc...

P.S. I'm pretty sure that Laurent and yourself are thinking in terms of TX initiated reconfigurations while I'm thinking in terms of RX initiated reconfigurations (adaptions since the RX can't talk to TX) .... For example, I'm outside the target area of a broadcaster, but I want my receiver to decode the digital broadcast if possible. Hence, I need it to switch to a mode where decoding is possible ... IF possible.

Last edited by tpreitzel : 14-11-2017 at 00:43.
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Old 14-11-2017, 00:49   #52
zfyoung
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Quote:
implying that the DRM standard has asymmetric ability
If you confine yourself within the 'rule box' of current DRM standard, then the answer is a resounding NO. That's why I said
Quote:
short term stopgap solutions
. But it does't mean you have to throw out the baby with dirty bath water. what I hinted is that there is Long Term Evolution of this standard (L.T.E. sounds familiar, eh?)that in the ultimate end brings out the best of analogue system and digital system.

PS. NO, laurent and I are talking about two different things, and given my academic background in information theory I know what I'm talking about: "Joint Source Channel Coding". If you not even heard about it, then google it.
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Last edited by zfyoung : 14-11-2017 at 00:57.
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Old 14-11-2017, 14:39   #53
tpreitzel
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Quote:
Originally Posted by zfyoung
If you confine yourself within the 'rule box' of current DRM standard, then the answer is a resounding NO. That's why I said . But it does't mean you have to throw out the baby with dirty bath water. what I hinted is that there is Long Term Evolution of this standard (L.T.E. sounds familiar, eh?)that in the ultimate end brings out the best of analogue system and digital system.

PS. NO, laurent and I are talking about two different things, and given my academic background in information theory I know what I'm talking about: "Joint Source Channel Coding". If you not even heard about it, then google it.

Given some time, I'll look into "Joint Source Channel Coding" ... so thanks for the information. Even without further investigation, I have already concluded that an HD-like system (automatic fallback to more robust digital configurations, e.g. 16 QAM) is preferable to the current DRM standard. The digital receiver needs to make an "intelligent" selection of the proper mode instead of relying on the whims of the broadcaster. However, the overhead would be significantly higher since all the data necessary for such a decision would have to be transmitted concomitantly.

Until the DRM standard is amended, I'll stand by the need for digital SW broadcasters to use MSCs of 16 QAM ...

I'll investigate further though.

Last edited by tpreitzel : 14-11-2017 at 14:47.
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Old 15-11-2017, 07:11   #54
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It might be possible to change the DRM modulation scheme so the receiver can use high fidelity when the signal is good but remain locked to the more robust signal when conditions are poor - from the same transmitted signal. The scheme adopted for satellite video transmission DVB-S2 allows for this (although I'm not aware of broadcasters using that aspect here)
http://www.etsi.org/deliver/etsi_tr/...76v010101p.pdf
However, anything added now should be backward compatible to existing gen-3
receivers, those who invested in DRM30 or DRM+ reception have been sidelined because of the introduction of xHE-AAC. I think that means only the Gospell and Titus can do DRM now. What about Diveemo?
Also take note what is happening with DAB in Britain: many new stations are starting up in DAB+ only, 32kbs mono. They are not interested in stereo because of the cost. FM analogue and even AMstereo (AMAX) now outperforms it in every aspect of quality. The BBC has to keep its main programmes on the DAB standard due to the millions of expensive car radios and home portables that arn't upgradeable (I have one)
The cellular operators like LTE because more streams over their network= more tariff because unlike broadcast, the listener pays for the transmission costs. LG are selling a DAB+ Android phone here and Australia with the advertised advantage of no data charges and better battery life for the user.

The two things I would like the gen-4 DRM release to include are - Diveemo support and Opus codec support.
The one thing I would like smartphones to have is DAB+,DRM+,AMAX on all bands 0.5 thru 240 MHz
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Old 16-11-2017, 01:48   #55
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This synthetic picture should give you a rough idea of
Quote:
dynamic configuration at the RX
,depending on the distance between TX and RX.
As what I've said, the best coding scheme should have the sensual analogue form while in spirit, not lost its digital acumen!
Attached Images
File Type: jpg JSCC.jpg (52.6 KB, 16 views)
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