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Old 08-04-2018, 22:57   #1
Braccini
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Radio Romania 11650 kHz DRM 16-QAM Spanish

Hello,

Dear Mr. Braccini,

Due of last days tuning difficulties with one of our transmitters, we had
to change to analog AM 13810 kHz and run DRM 15670 kHz.
We are in progress to modify the settings of one transmitter to DRM mode D,
16 QAM (recommended to be used for long distances) and keep the other one
with actual settings for near distances.
According with prediction for new A18 season, the best bands are 13 MHz and
15 MHz - they are little bit better than 11 MHz and 13 MHz.
As differences are not significant, we propose to run a test as follow:
this week we'll continue running 15670 kHz in DRM, and next week we'll test
11650 kHz in DRM (this is completely clear channel), and kindly ask you to
send us a feedback.

Thank you and best regards.

RADIOCOM
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Old 08-04-2018, 23:05   #2
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RRI 11650 kHz DRM in South Brazil

Amazing signal, without breakes in Montenegro-RS, Brazil. I'm very happy, because RRI answer my request, changing to 16-QAM MSC and broadcasting in 25mb (11650 kHz), excelente band for A18 and B18 cycles and modulation. It's the result of a hard work, sending various e-mais and calling to RADIOCOM and Radio Romania. Thanks for all 🙏🙏🙏

VIDEO: https://youtu.be/75K19ItSyAM

Last edited by Braccini : 09-04-2018 at 05:09.
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Old 08-04-2018, 23:45   #3
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At what time? In UTC please.
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Old 09-04-2018, 00:20   #4
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Quote:
Originally Posted by Digger
At what time? In UTC please.
Hello Terje, RRI is broadcasting at 21h UTC to South America in this frequency. Clint 73 from Brazil!

Last edited by Braccini : 09-04-2018 at 00:25.
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Old 09-04-2018, 01:25   #5
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Good for you, Clint. I kind of laugh at RRI's rationale, though, which is typical of an engineer's study, not experience. Use 16 QAM modulation ALWAYS on shortwave, RRI! Mode D ought to be interesting, though. At least you managed to twist their arm enough to try it. LoL ... Great job!

Last edited by tpreitzel : 09-04-2018 at 01:29.
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Old 09-04-2018, 05:12   #6
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Quote:
Originally Posted by tpreitzel
Good for you, Clint. I kind of laugh at RRI's rationale, though, which is typical of an engineer's study, not experience. Use 16 QAM modulation ALWAYS on shortwave, RRI! Mode D ought to be interesting, though. At least you managed to twist their arm enough to try it. LoL ... Great job!
Thanks, I hope it extends to all DRM transmissions of RRI 😊
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Old 09-04-2018, 05:26   #7
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Good heavens! Mode C is bad enough. Audio from Mode D is probably "D"readful! However Clint, thanks for the time info. Just for fun I'll sharpen my antenna in Japan!
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Old 09-04-2018, 13:03   #8
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Wink

Quote:
Originally Posted by Digger
Good heavens! Mode C is bad enough. Audio from Mode D is probably "D"readful! However Clint, thanks for the time info. Just for fun I'll sharpen my antenna in Japan!
They are using B mode, but need set to use AAC+ codec (+SBR). It's possible with 16-QAM onde the MSC. Clint 73!
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Old 09-04-2018, 22:29   #9
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RRI, 11650 kHz, Reception near Atlanta, Georgia, USA

This afternoon's reception - beamed to South America - 9.05% audio decoded, 13.49 dB max SNR.
Attached Images
File Type: png 11650-180409-2100-2158-Zyg.png (36.6 KB, 73 views)
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Old 09-04-2018, 23:58   #10
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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.
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File Type: png 11650-180409-2143-2157-Terje@JPN.png (36.2 KB, 71 views)
File Type: jpg TIGnearSantosBRA.jpg (78.7 KB, 65 views)
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Old 10-04-2018, 10:21   #11
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RRI 11650 kHz DRM in South Brazil 9 APR 18

Today I had failures in the second half hour of transmission, possibly by propagation, but it was not a big problem, because they had listeners who did not have flaws. I ask that broadcaster always maintain 300 KW of power.

VIDEO: https://youtu.be/W_a8G07jzk8
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Old 10-04-2018, 13:27   #12
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I think it's 90 kW DRM.
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Old 10-04-2018, 14:54   #13
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Quote:
Originally Posted by Digger
The result was 3000 Hz audio bandwidth. The audio quality was therefore not the best, but the reception was stable.

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.
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Old 10-04-2018, 18:13   #14
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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.

Nonsense with a capital "N" on several fronts. Several digital SW broadcasters like VoR had absolutely no problem using Journaline with 16 QAM modulation. 16 QAM modulation fully support SBR as well which is certainly better than listening to large blocks of silence with 64 QAM. If higher audio quality is desired, try the medium wave band instead of shortwave.

Last edited by tpreitzel : 10-04-2018 at 18:25.
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Old 10-04-2018, 22:48   #15
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No signal received on 11650 kHz this afternoon.
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