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Old 19-02-2020, 00:38   #1
AF4MP
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VOA Radio Marti DRM 7345 kHz

Today was able to decode the xHE-AAC mode transmitted by Radio Marti 7345 kHz from the VOA transmitter site near Greenville, North Carolina.

The receiver was the Ten-Tec RX320D running the latest Dream 2.2.1 Linux software (that I finished compiling this morning). The antenna was the long wire lying on the ground and snapped in two pieces by a recent heavy storm.

Signals were strong with the SNR peaking over 21 dB!

I was going to attach a reception log but the DRM Log plotter apparently does not like the output from the xHE-AAC decoder.

Attached are the received station ID and the DRM constellation.
Attached Images
File Type: png Radio Marti 18-feb-20.png (26.9 KB, 125 views)
File Type: png Radio Marti Constellation 18-feb-20.png (21.2 KB, 115 views)
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Old 20-02-2020, 21:52   #2
AF4MP
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VOA Radio Marti DRM 7345 kHz

This afternoon's reception - Audio/SNR graph (15 minute duration) from the evaluation screen starting at 2122z (attachment 1).

There is a multi-media slide show also transmitted. Although they show the number as four slides, there only two, repeated as 3 and 4 (Attachment 2 shows the first slide).

The receiver is my Kenwood R-1000 modified with a Sat-Schneider crystal controlled mixer/convertor.

The antenna is a about 3 meters of wire lying on the ground (the remains of the long wire that was torn apart by recent storms)!

Please notice that there is audio decoding at a low SNR of about 12 dB.
Attached Images
File Type: png Radio Marti SNR-Audio 20-Feb-20.png (18.3 KB, 105 views)
File Type: png Radio Marti MOT 1 20-Feb-20.png (18.6 KB, 109 views)
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EM74ta

Last edited by AF4MP : 21-02-2020 at 03:23. Reason: low SNR typo: changed 20 db to 12 dB
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Old 21-02-2020, 01:29   #3
tpreitzel
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Codec +
Modulation +
Frequency +

Excellent configuration and production by VoA which should be emulated by most other digital broadcasters via shortwave. VoA might experiment with Mode A or stereo. but otherwise the broadcast is still excellent... with just 10 kbps data rate. Bravo!

VoA is my generic reference for any broadcast from their site in NC.

Last edited by tpreitzel : 21-02-2020 at 01:36.
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Old 23-02-2020, 10:20   #4
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VoA's production and configuration are good enough to clearly reveal a flawed performance of female announcer who was too close to the microphone...


The xHE-AAC codec is wonderful and 16 QAM enables the listener to enjoy the broadcast...great stuff.
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Old 23-02-2020, 16:27   #5
AF4MP
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VOA Radio Marti DRM 7345 kHz

The audio spectrum from this afternoon's transmission.
Attached Images
File Type: png Radio Marti Audio Spectrum 23Feb20.png (12.2 KB, 120 views)
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Old 28-02-2020, 23:17   #6
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Hi,

I'll just post something here so I can get the notifications! ;-)
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