DReaM and gnuradio

Hi Gang - Did somebody have the DRM decoder working with a gnuradio
receiver? The main issue is feeding the sound from gnuradio into DReaM,
somehow, other than using two soundcards. I have DReaM 1.6.25 compiled.

TIA

–Chuck

Charles S. wrote:

Hi Gang - Did somebody have the DRM decoder working with a gnuradio
receiver? The main issue is feeding the sound from gnuradio into DReaM,
somehow, other than using two soundcards. I have DReaM 1.6.25 compiled.

http://sourceforge.net/projects/drm/

TIA

–Chuck

Hello,

I am setting up the DReaM decoder using the USRP. I am gradually
getting it to work and managed to copy Radio New Zealand this morning on
9690. I was using the “No-Mod” DRM Mod for the AOR 5000 but found I
needed a very good signal to get anything.

I am using the 10.7 MHz IF out of my AOR 5000 reciever connected to the
USRP with Basic RX via a torroid transformer. The transformer was
originally used to cut down noise but I had to make it a step-up
transformer to increase the signal level. The secondary is connected to
RX A and RX B as a differential input.

I used similar code to what was posted on the list in 2005 to convert
the 10.7 MHz to baseband. I resample the baseband from 64000 samples
per second to 48000 samples per second and output it to a Griffin iMic
USB Audio dongle. I am outputing “stereo” (I/Q).

I am going to try using Jack to loopback the audio but currently I am
looping the iMic output to the iMic input. DReaM is setup to use I/Q by
using the -c 4 parameter. I use -c 4 because the IF Output spectrum is
inverted. DReaM outputs to my main speakers on the laptop.

The laptop I use does not have line in so I use the iMic for other
decoding and get two outputs in the process. The iMic is not very
expensive but using jack is even cheaper.

73 Eric

Hi All,
I wrote a graphical dream example script for gnuradio which works with a
fifo (No extra soundcards needed):
You can find the example at:
http://www.olifantasia.com/projects/gnuradio/mdvh/examples/dream/
(You need both files)

Here is the Readme:
This is a dream example script for gnuradio.
You can choose from a list of channels in the gnuradio gui and set
frequency and gain there.
You can set the drm parameters in the dream gui.
It works for me using nothing more then usrp, basic_RX and a piece of
wire although I only get the strong stations this way.
(No amplifiers used).

usrp_drm_rcv.py is the graphical dream gnuradio example.
You need drm_rcv.py in the same directory (This is the guts hierarchical
block for dream used by usrp_drm_rcv.py)

The example will automatically start dream for you and open a pipe with
a stream of samples for dream in the right format (on linux)

So for the dream python examples you need to have a version of dream
installed.
You can find dream at:
http://drm.sourceforge.net/

You can also find patched sources in
http://www.olifantasia.com/projects/gnuradio/mdvh/examples/dream/required/

drm-patch-mdvh.diff is a patch I developed to get dream to work on my
machine (debian sarge).
There is a little bug in the original drm-1.6.25 source.
It hangs if cat /dev/sndstat gives out lines with more then 20 chars.
This patch solves this.

I also put up a source tarball in required which includes this patch.

I also found some binaries on the net for debian which also seem to work
You can find these at:
http://duch.cz/drm/dream/debian/

Greetings,

Martin Dudok van Heel

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