DRM trial II in Sottens

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Following the amateur radio DRM trial on the phased out shortwave antenna in Sottens in 2004, it has been decided to make another amateur radio DRM trial but this time on the 188m MW antenna that has just been phased out on 31.12.2010.

Transmission schedule

The tests will happen on 13th February 2011 and 20th February 2011 with 15 minutes periods on the following times (same for both sundays):

  • 20h-20h15 CET (19h-19h15 UTC) TX on 7.180 MHz
  • 21h-21h15 CET (20h-20h15 UTC) on 3.780 MHz

We will use the narrowest band so 4.5kHz and high robustness to transmit slides.

Please send your reception reports to sottens@hb9mm.com

Original audio loop transmitted


Setup1.jpg Setup2.jpg First stage.jpg Final stage.jpg Power out.jpg Transmission laptop.jpg Gnuradio.jpg Reception monitor.jpg Dream receiver.jpg Commercial DRM receiver.jpg

  • Spark software (free full license gracefully offered by Michael Feilen)
  • USRP with LFTX daughterboard
  • Mini-circuits Gali74+ amplifier
  • Preamplifier recycled from the bin from Asulab by Yves (HB9DTX)
  • Amateur radio linear amplifier.

Mode used:

  • 4.5kHz, Mode B, MSC 16QAM, EEP code rate 0.5, AAC audio at 4.8kbit/s
  • 4.5kHz, Mode B, MSC 64QAM, EEP code rate 0.5, AAC Audio, MOT Slideshow at 2.56 kbits/s


To follow...

See also: http://www.drmrx.org/forum/showthread.php?t=2307


Credits to Yves HB9DTX, Stan from Maxxima, the HB9MM amateur radio club and Swisscom for lending them for a month such a great antenna. At least Sottens will have gone digital before dying. It shows also that DRM transmission can be done with limited equipment (apart from antenna), an interesting thing for local or community radio. Mathias HB9UFQ

See also

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