[op25-dev] RE: Package gnuradio-core was not found error

ikj1234i at yahoo.com ikj1234i at yahoo.com
Sat Jan 18 18:16:57 UTC 2014

Hi Scott

 We in turn owe much credit to the GNU Radio developers, and a host of others including the osmosdr team.

 There is an app osmocom_fft -- see http://sdr.osmocom.org/trac/wiki/GrOsmoSDR .

 That app should already be installed and all set to run since gr-osmosdr is installed by pybombs as a prereq for op25.

 It has GUI controls for setting the variable RF gain(s).  You should see a separate slider for each programmable gain that the RTL stick supports (assuming it has this at all I suppose).  I don't have an RTL USB stick - still waiting for my order to be delivered.  Would be interested to hear what happens in osmocom_fft - are you able to see any of the LSM CC's using that?  There are a few other things to try also using osmocom_fft - first instead of tuning to the exact frequency of the signal, tune (say) 50 KHz offset from the frequency - so if the station you want is at 157.125 try tuning 157.175 - then look for your desired signal 50 KHz leftward from center.  Reason for this is to try to avoid the dreaded "DC offset" problem.  Another thing to do is add an FM trap (if needed).  Anyway, both of the above tuning issues are taken care of with extra parameters to scope.py.  But first it's necessary to confirm your RTL can see the signal at all, so it would be good to give osmocom_fft a spin.  Also please paste the command line you're using when running scope.py



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