[op25-dev] Re: "Could not find a decoder to use"

Souf Hadoken souf308 at yahoo.com
Thu Apr 18 01:15:24 UTC 2013

Hi Matt,
I would like first to thank you for your help the last weeks (I spend my spring break locked in my room trying to make the OP25 block and gnu radio work).
You gave me really good indications and instruction. After another atemp staring from a clean disk I manage to make the file work and could listen to the sound.

No I'm in the phase where I'm using an USRP. I manage to make it work and detected but Im stuck at a point where you have been (according to the archive of the groupe discussion):

-I can see the 4 ligne of the 4FSK BUT I HAVE NO AUDIO.

I think it's a probleme of sample rate, channel rate and things like that.
Could you help me by giving me some explanations like do the channel rate from the OP25 block should be perfectly maching the audio sink?
what is the difference between channel rate and sample rate?
What is the bandwith in the USRP and how should it be?

thanks for your help

 From: Matt D <md123 at nycap.rr.com>
To: op25-dev at yahoogroups.com 
Cc: souf308 <souf308 at yahoo.com> 
Sent: Thursday, April 4, 2013 6:34 AM
Subject: Re: [op25-dev] Re: "Could not find a decoder to use"

Hash: SHA1

On 04/04/2013 04:24 AM, souf308 wrote:
> Hi,
> So I reinstaled OP25 and had everything get configured with almost
> any error. I also applied the patch I still have the same error
> message: ---------------------------------------------------- File
> "/home/souf/gr-baz-master/samples/op25_grc.py", line 243, in
> __init__ self.op25_decoder_0.create() File
> "/usr/local/lib/python2.7/dist-packages/baz/op25.py", line 88, in
> create raise Exception("Could not find a decoder to use") 
> ----------------------------------------------------
> So I tried to understand the op25.py file and copied more files in
> the OP25 PYTHON directorie in case something was missing in the
> 'import' but it did not work.
> Here is a part of the op25.py where the problem occurs:
> ------------------------------------------------------ def
> create(self): self.op25_msgq = gr.msg_queue(2) self.slicer = None 
> try: levels = [ -2.0, 0.0, 2.0, 4.0 ] self.slicer =
> _op25.fsk4_slicer_fb(levels) self.p25_decoder = _op25.decoder_bf()
> # FIXME: Message queue? if _verbose: print "Using new decoder_bf" 
> except: try: self.p25_decoder = _op25.decoder_ff(self.op25_msgq)
> # LEGACY if _verbose: print "Using legacy decoder_ff" except: raise
> Exception("Could not find a decoder to use")
> ----------------------------------------------------
It is unlikely that the code is broken.  How do you start the program?
always start in terminal "sudo gnuradio-comapanion"
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Comment: Using GnuPG with undefined - http://www.enigmail.net/


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