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-   -   Radio Romania 11650 kHz DRM 16-QAM Spanish (http://www.drmrx.org/forum/showthread.php?t=2792)

Braccini 10-04-2018 23:16

RRI 11650 kHz DRM in South Brazil 10 APR 18
 
Weak signal in Brazil, without decoding. It looks like 90 KW if it reaches this power.

Braccini 10-04-2018 23:51

AAC+ SBR 16-QAM PS CD QUALITY IS POSSIBLE
 
Quote:

Originally Posted by AF4MP
Hi Terje,

The RRI 9760 kHz transmission is also now using 16 QAM with its low bit rate of 11.64 kbps. I posted the audio 3.5 kHz bandwidth plot in that thread.

Although the audio sounds "pretty good" it is, after all, the same or very similar bandwidth to a telephone circuit. A 3.5 kHz wide SSB transmission would sound just as good, and have much greater range.

As 16 QAM provides only telephone type quality, and no extra features such as Journaline, etc., and it requires a wider RF bandwidth and higher SNR to receive than analog SSB channel; I'm trying to understand the rationale of using the low fidelity mode?

My interest and embrace of "DRM" is its high quality audio plus extra features that cannot be achieved by analog transmission. 16 QAM does not provide that.


Amazing and possible AAC+ SBR Parametric Stereo 16-QAM MSC test local in Brazil: https://www.youtube.com/watch?v=EulR802VrSg

AF4MP 11-04-2018 01:27

Quote:

Originally Posted by Braccini
Amazing and possible AAC+ SBR Parametric Stereo 16-QAM MSC test local in Brazil: https://www.youtube.com/watch?v=EulR802VrSg


Hi Clint,

OK very good example - but that is using xHE-AAC (AAC+SBR+PS) and this transmission is using AAC only.

I'm not aware of any xHE-AAC transmissions at this time.

Now even when using xHE-AAC configured for maximum fidelity, with 16QAM, there will not be enough bandwidth remaining for extra neat features like multimedia etc.

tpreitzel 11-04-2018 01:55

Isn't it ironic that some members who complain about the quality of audio with 16 QAM modulation only know because 16 QAM modulation allowed them to judge in the first place by enabling decoding. ;) Other members feel compelled to use the SpyNet which allows them to circumvent poor configurations, e.g 64 QAM modulation, by using a receiver closer to the center of a broadcast's beam. Although 16 QAM modulation isn't a panacea for every eventuality on shortwave, it'll be the default eventually regardless of mine or Clint's insistence. Why? 16 QAM is somewhat reliable to decode on SW with most receivers while 64 QAM is not. No amount of words will change this fact.

BTW, Clint, since you did such an excellent job persuading Radiocom to switch to 16 QAM modulation, can you convince them to switch two digltal SW broadcasts of RRI, one to S. America and one to N. America, to the xHE-AAC codec from ancient AAC+ while maintaining 16 QAM modulation? Include SBR/PS if Radiocom agrees and ask Radiocom to avoid frequencies used by Cuba, e.g. 7335 kHz. If you do and RRI maintains such a configuration for awhile, at least 6 months, I'll pay you $100 which should cover shipping charges for a new GR-216 to Brazil. Just don't ask me to register with PayPal ;)

Cumbredx 11-04-2018 10:31

3000 hz
 
Quote:

Originally Posted by Digger
No traces of DRM on this frequency in Japan this morning. 11 MHz is pretty full of chirps here at my temporary location. However, sometimes I can see RRI via the back of the beam.

Here is a short log which I made with a Kiwi SDR in Rio Grande da Serra, Brazil. RRI used Mode B, 11 kbps and 16 QAM. The result was 3000 Hz audio bandwidth. The audio quality was therefore not the best, but the reception was stable.


Hi, is there a formula that tells you that B, 11 kbps, 16 QAM = 3 kHz audio or does it depend.

Cumbredx 11-04-2018 10:35

xHE-AAC
 
Quote:

Originally Posted by AF4MP
Hi Clint,

OK very good example - but that is using xHE-AAC (AAC+SBR+PS) and this transmission is using AAC only.

I'm not aware of any xHE-AAC transmissions at this time.

Now even when using xHE-AAC configured for maximum fidelity, with 16QAM, there will not be enough bandwidth remaining for extra neat features like multimedia etc.


Isn't this actually HE-AAC v2 rather than Extended HE-AAC (xHE-AAC).

Cumbredx 11-04-2018 10:44

xHE-AAC In General and RRI in Particular
 
1 Attachment(s)
Quote:

Originally Posted by tpreitzel
Isn't it ironic that some members who complain about the quality of audio with 16 QAM modulation only know because 16 QAM modulation allowed them to judge in the first place by enabling decoding. ;) Other members feel compelled to use the SpyNet which allows them to circumvent poor configurations, e.g 64 QAM modulation, by using a receiver closer to the center of a broadcast's beam. Although 16 QAM modulation isn't a panacea for every eventuality on shortwave, it'll be the default eventually regardless of mine or Clint's insistence. Why? 16 QAM is somewhat reliable to decode on SW with most receivers while 64 QAM is not. No amount of words will change this fact.

BTW, Clint, since you did such an excellent job persuading Radiocom to switch to 16 QAM modulation, can you convince them to switch two digltal SW broadcasts of RRI, one to S. America and one to N. America, to the xHE-AAC codec from ancient AAC+ while maintaining 16 QAM modulation? Include SBR/PS if Radiocom agrees and ask Radiocom to avoid frequencies used by Cuba, e.g. 7335 kHz. If you do and RRI maintains such a configuration for awhile, at least 6 months, I'll pay you $100 which should cover shipping charges for a new GR-216 to Brazil. Just don't ask me to register with PayPal ;)


Wouldn't xHE-AAC include SBR and PS by default?

Is RRI capable of broadcasting in xHE-AAC?

Cumbredx 11-04-2018 10:48

Quote:

Originally Posted by AF4MP
Hi Clint,

OK very good example - but that is using xHE-AAC (AAC+SBR+PS) and this transmission is using AAC only.

I'm not aware of any xHE-AAC transmissions at this time.

Now even when using xHE-AAC configured for maximum fidelity, with 16QAM, there will not be enough bandwidth remaining for extra neat features like multimedia etc.


No xHE-AAC on shortwave, but I believe that AIR is broadcasting in xHE-AAC on 621 and 828 kHz with 16 QAM and is able to transmit Journaline.

Braccini 11-04-2018 10:53

Quote:

Originally Posted by tpreitzel
Isn't it ironic that some members who complain about the quality of audio with 16 QAM modulation only know because 16 QAM modulation allowed them to judge in the first place by enabling decoding. ;) Other members feel compelled to use the SpyNet which allows them to circumvent poor configurations, e.g 64 QAM modulation, by using a receiver closer to the center of a broadcast's beam. Although 16 QAM modulation isn't a panacea for every eventuality on shortwave, it'll be the default eventually regardless of mine or Clint's insistence. Why? 16 QAM is somewhat reliable to decode on SW with most receivers while 64 QAM is not. No amount of words will change this fact.

BTW, Clint, since you did such an excellent job persuading Radiocom to switch to 16 QAM modulation, can you convince them to switch two digltal SW broadcasts of RRI, one to S. America and one to N. America, to the xHE-AAC codec from ancient AAC+ while maintaining 16 QAM modulation? Include SBR/PS if Radiocom agrees and ask Radiocom to avoid frequencies used by Cuba, e.g. 7335 kHz. If you do and RRI maintains such a configuration for awhile, at least 6 months, I'll pay you $100 which should cover shipping charges for a new GR-216 to Brazil. Just don't ask me to register with PayPal ;)


Certainly 7330 from RRI at night has been greatly affected by Havana Cuba 7335. This week is testing on 11650 kHz, and as requested, I am sending feedback to the broadcaster, including the AAC + SBR codec issue.
It would be very nice to have the Gospell GR 216 :D
Best regards,
Francisco Braccini

Digger 11-04-2018 11:52

At least MOI Kuwait used the xHE-AAC for a short while in 2017 (I got that confirmed) and could even decode it (the IF signal) with the Avion Receiver a while back when I lived in Sweden.

AF4MP 11-04-2018 15:18

Quote:

Originally Posted by Cumbredx
Isn't this actually HE-AAC v2 rather than Extended HE-AAC (xHE-AAC).


Yes, you are correct. xHE-AAC is an upgrade to HE-AAC v2.

AF4MP 11-04-2018 15:23

Quote:

Originally Posted by Digger
At least MOI Kuwait used the xHE-AAC for a short while in 2017 (I got that confirmed) and could even decode it (the IF signal) with the Avion Receiver a while back when I lived in Sweden.


Were they running it on 16-QAM?

oh2bfo 11-04-2018 15:31

Quote:

Originally Posted by Cumbredx
Hi, is there a formula that tells you that B, 11 kbps, 16 QAM = 3 kHz audio or does it depend.

RRI's current configuration is mode B, 16-QAM, protection level 1 (code rate 0.62). That gives you 14.56 kbps, but for some reason they choose not to use the full channel capacity! (Most likely it's unintentional.)

I remember lots of broadcasters having excellent audio using this configuration. And BBC/DW often did a combination of mode A with 16-QAM giving them 18.44 kbps to play with.

AF4MP 11-04-2018 17:14

Quote:

Originally Posted by oh2bfo
RRI's current configuration is mode B, 16-QAM, protection level 1 (code rate 0.62). That gives you 14.56 kbps, but for some reason they choose not to use the full channel capacity! (Most likely it's unintentional.)


Perhaps they got mixed up with protection level 0 which is 11.6 kbps?

Quote:

Originally Posted by oh2bfo
I remember lots of broadcasters having excellent audio using this configuration.


Was that mono or stereo?

Quote:

Originally Posted by oh2bfo
And BBC/DW often did a combination of mode A with 16-QAM giving them 18.44 kbps to play with.


However Mode A is not recommended for shortwave.

Considering that the main reasons for adopting DRM was excellent audio including stereo and other features. My inital question, although perhaps not well stated, was what is the reason to have 16-QAM be the default mode for shortwave? I understand that there are situations where 16-QAM is required, but 64-QAM provides more capacity/services and works very well in
its target areas.

oh2bfo 11-04-2018 21:30

Quote:

Originally Posted by AF4MP
Was that mono or stereo?

Probably mono, but parametric stereo would not really require lots of additional bps. I think I've seen PS used with something like 16 kbps. But although PS sounds kind of fun with pop music, mono is often better for mostly speech content and also other types of music.
Quote:

Originally Posted by AF4MP
However Mode A is not recommended for shortwave.

Nevertheless it worked just fine for one-hop paths. I'm pretty sure the BBC/DW guys used mode A with 16-QAM quite deliberately.
Quote:

Originally Posted by AF4MP
Considering that the main reasons for adopting DRM was excellent audio including stereo and other features. My inital question, although perhaps not well stated, was what is the reason to have 16-QAM be the default mode for shortwave? I understand that there are situations where 16-QAM is required, but 64-QAM provides more capacity/services and works very well in its target areas.

[emphasis added]
I fully agree with that. But I suppose a lot of people here (you, for example!) don't live in the target areas of any DRM broadcasts. So DRM is really 'DX' for most listeners, and it's not hard to understand their preference of 16-QAM.


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