op25-dev September 2013

op25-dev@lists.osmocom.org

4 participants
5 discussions

bch.cc
by Matt D 09 Dec '13

09 Dec '13

Hey guys, Can anyone please explain to me what is going on in bch.cc? I am trying to figure out what ECC is used in there and where it is used exactly. Thanks -- ------ Matt D ------------

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Correct decoder: op25_decoder_ff.cc or op25_decoder_bf.cc
by trinmole 11 Sep '13

11 Sep '13

I am trying to use the OP25 blocks for a C++ program. I have everything running fine as a .GRC. I also have a makefile to bundle everything up into a library. I am confused which C++ blocks I should be using - should it be op25_fsk4_demod_ff.cc connected to op25_decoder_ff.cc ? op25_decoder_ff.h get exported to /usr/include/ however only op25_decoder_bf.cc is included in the Makefile.am There is no op25_fsk_demod_fb.cc so I am not sure how I would connect the decoder_bf block in. What are the correct C++ blocks to use to replicate the "OP25 FSK4 Demod" & "OP25 Deocder" Python Blocks? Are there any C++ programs I could use as an example? Thanks for any pointers! - Luke

3 5

hamming decoder
by Matt D 07 Sep '13

07 Sep '13

Hey, I am interested in writing the shortened hamming decoder and rs decoder for the LC information. Is there any sort of reference manuals that describe how the shortened hamming code is implemented? From looking at the op25 lib; op25_hamming.h in particular, it looks like its being done bitwise in hamming_15_decode function. i just really don't know what that giant encoding array & the small decoding array are and how those relate to the generator matrices in the tia pdf? i think i kind of have to know what those are about before i can proceed to write a decoder of the LCWs. But thereafter i suspect it shouldn't be to hard. the matrix algebra approach is how i understand how to decode hamming codes and that approach is not used in op25. furthermore I am not sure if implementing an algebraic approach would be appropriate (ie. fast enough) for our use here? so it would be a big help if I knew how exactly the hamming_15_decode function works, and in particular what those to arrays (encoding & decoding) are, and where they come from, and how the generator and parity matrices (or functions) are utilized? Thanks! -- ------ Matt D ------------

1 0

pointer error
by Matt D 05 Sep '13

05 Sep '13

on my most recent crash there was a little more information than before. after the memory map in the shell where the crash occurred there is now this message: ^CTraceback (most recent call last): File "/usr/local/bin/gnuradio-companion", line 63, in <module> ActionHandler(args, Platform()) File "/usr/local/lib/python2.7/dist-packages/gnuradio/grc/gui/ActionHandler.py", line 70, in __init__ gtk.main() and the new from gdb: warning: .dynamic section for "/usr/local/lib/python2.7/dist-packages/gnuradio/gr/_gnuradio_core_runtime.so" is not at the expected address (wrong library or version mismatch?) -- ------ Matt D ------------

1 0

trying to debug a bad pointer error [1 Attachment]
by Matt D 03 Sep '13

03 Sep '13

Hi, When compiling i did 'configure --enable-debugging'. so the memory error finally crashed op25 and the core file dumped. i ran 'sudo gdb /home/matt/OP25_GRC/op25_grc.py /home/matt/core.8995'. I hardly got anything out of gdb (i attached a copy of what was in terminal) but it did say the /home/matt/OP25_GRC/op25_grc.py was not in executable format: file format not recognized. What am I doing wrong here? -- ------ Matt D ------------

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op25-dev September 2013