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Re: [Discuss-gnuradio] Error in OP25 Decoder block

From: Doug Hutton
Subject: Re: [Discuss-gnuradio] Error in OP25 Decoder block
Date: Fri, 18 Jul 2014 12:51:46 -0500
User-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0

I probably overdid the stuff below, but I did try your other suggestion.
I made your change in -

I kept the original stuff in the copyright comments.   The lines in your suggestion above the
_verbose = True       line were not in my op25.py.

I noticed in the GRC Welcome statement that this is Version 3.7.5 - I presume it is the same
as in the 3.7.4 release notice that came out this week.

# the Free Software Foundation, Inc., 51 Franklin Street,
# Boston, MA 02110-1301, USA.
# import math
# from gnuradio import gr, gru, op25 as _op25

_verbose = True

import math
from gnuradio import gr, gru
import op25 as _op25

    from gnuradio import fsk4   # LEGACY


Here are the results:

<<< Welcome to GNU Radio Companion 3.7.5git-0-g2bb2b314 >>>

Preferences file: /home/doug/.grc
Block paths:

XML parser: Found 1 erroneous XML file while loading the block tree (see "Help/Parser errors" for details)

Loading: "/home/doug/Documents/Op25 project files/Doug-op25.grc"
>>> Done

Showing: "/home/doug/Documents/Op25 project files/Doug-op25.grc"

Generating: "/home/doug/Documents/Op25 project files/top_block.py"

Executing: "/home/doug/Documents/Op25 project files/top_block.py"

linux; GNU C++ version 4.8.2; Boost_105400; UHD_003.007.001-84-gd99ce4ef

Using Volk machine: sse4_a_64
RTL2832 Source block configuration:
    Read length (bytes): 262144
    Buffer enabled: yes
    Buffer multiplier: 8
    Buffer size (samples): 1048576
    Samples per read: 131072
    Buffer level: 50.0%
Kernel driver detached.
Successfully initialised demod: "ezcap EzTV"
Probing "e4k"...not found.
Probing "fc0013"...not found.
Probing "fc2580"...bad check value.
Probing "r820t"...found.
Found RTL2832 device: ezcap EzTV (tuner: Rafael Micro R820T)
    Sample rate range:    900001 - 3200000 Hz
    Crystal frequency:    28800000 Hz
[r820t] Initialised (default bandwidth: 0 Hz)
Wait delay: 196.608 ms
Traceback (most recent call last):
  File "/home/doug/Documents/Op25 project files/top_block.py", line 185, in <module>
    tb = top_block()
  File "/home/doug/Documents/Op25 project files/top_block.py", line 113, in __init__
    self.op25_decoder_simple_0 = op25.op25_decoder_simple(key="",)
  File "/home/doug/usr/local/lib/python2.7/dist-packages/baz/op25.py", line 98, in __init__
    raise Exception("Could not find a decoder to use")
Exception: Could not find a decoder to use
Kernel driver reattached.

>>> Done


Back in early June, near when I started this project, I emailed Balint from his Spench.net site.
I knew he was having too much fun working on ISEE3, but on July 4, he sent me the following note:
Hi Doug,
Thanks for your email. Glad to hear you're getting into SDR! Lots of interesting signals to discover...

That wiki page was actually contributed by someone else, and (as you've seen) things have changed in OP25 since his instructions were compiled. I'm not sure what happened to the OP25 build script, but I put it back. I would suggest that you follow the instructions on the official OP25 site now though as the build process is different AFAIK.

 I think you're on the op25-dev mailing list now, so hopefully you'll be able to get some more answers there. All I can suggest from here is that as long as you have GNU Radio installed, you should just be able to either install the OP25 source yourself from the git repository (and manually satisfy its dependencies) and build/install, or use the PyBOMBs script to do it all. PyBOMBs will also install GNU Radio, so if you already have it installed, make sure you tell PyBOMBs that GNU Radio is already installed (IIRC when you run it the first time you can tell it what dependencies are already manually satisfied).

Best place to ask is the list though because I haven't played around with it in a while
Good luck.
Kind regards,

I don't really understand his Pybombs comments, but apparently, he has moved on.

I presume that all of my grief is because I started out with  3.7 GNURadio , and that a realistic
way to get op25 working is to back off to 3.6.  I really don't want to do that if there is any other way.

You may have read one of my previous posts on op25-dev where I described why I am really anxious
to be able to listen to the new Lubbock Harris op25 phase 2 system.  I have talked to two different Lubbock Police officers who have seriously complained that the audio on their new radios is so bad that they are unwilling to risk using them.  I have a new Uniden BCD 436HP, and the audio on it is pretty bad. 

Thanks very much for your help, Max.  Lemmee know if you can think of a good way out of this.

Doug H.

On 7/18/2014 11:51 AM, ikjtel wrote:
> >>> import op25
> >>>
> I got the prompt right back, no error message.

Right - pretty much as expected.  This strongly suggests that the python code you're attempting to use (in this case, from gr-baz) has not yet been forward-ported so as to be compatible with the new GR version 3.7.x API's (and with the new op25 version which has been converted to be compatible with the same).   The amount of effort to make it compatible is a total unknown at this point (assuming the tiny patch to the import statements isn't sufficient, that is); Balint would know for certain...

Anyway, to summarize, the test that you ran (above) indicates that the GR-3.7.x-compatible version of op25 is in fact installed (just not in the way that gr-baz is looking for it)...


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