DATV-Express SSB TX with GNURadio

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M0DTS
Posts: 684
Joined: Sun Feb 24, 2008 9:03 pm

DATV-Express SSB TX with GNURadio

Post by M0DTS » Mon Apr 07, 2014 9:56 am

Had a play late last week with gnuradio and the DATV-Express.

I made a 'bodge' of an SSB transmitter, gnuradio flow path screenshot is attached.
You could use an RTL-SDR dongle as the rx and a changeover relay to make a full ssb transceiver.

Audio is taken in from the soundcard and converted to complex IQ signal, the upper sideband of this complex signal is filtered.
This is then goes into a very crude AGC circuit and then into a resampler to take it upto 2048ks/s complex signal for the DATV Express output.

I will put some more info on my website when i get time, i used the newer version of gnuradio so making the gnuradio file available will be tricky as most are still uing the older version so it would not work.
The gnuradio DATV Express sink module is here: https://github.com/csete/gr-datvexpress

73

Rob
Attachments
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right click, view image for a better view!
Express SSB.png (317.32 KiB) Viewed 4395 times

KenW6HHC
Posts: 309
Joined: Mon Jun 01, 2009 4:20 pm

Re: DATV-Express SSB TX with GNURadio

Post by KenW6HHC » Tue Apr 08, 2014 2:56 pm

Hi Rob M0DTS,

Thanks for sharing your efforts with GNURadio and DATV-Express to transmit SSB.

You showed a plot of the FFT spectrum for SSB (very clean). Can you post a screen-capture of your SSB signal using a Spectrum Analyzer? I am just curious of any differences between the "math model" and the "real world".

73...de Ken W6HHC

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