need some help with GR-baz OP25

[richard kellogg]

I just got my RTL2832U  and I'm trying to get OP25 from gr-baz to work and im stuck.

I started from a clean disk and  installed ubuntu 12.04. Then the standard  " wget http://www.sbrac.org/files/build-gnuradio && chmod a+x ./build-gnuradio && ./build-gnuradio" install - which worked with no warnings/errors.

Then followed by installing op25, and gr-baz.

The rtl-test and rtl-FM worked (i could hear the FM station).  In grc-companion, with a rtl2832U source connected to a  FFT sink - I can see carriers on local radio stations - so I believe the usb DTV dongle is working - and that i have installed the gnu radio software correctly.

But when I use op25.grc from gr-baz,and tune to my local county P25 control frequency - looking at the 4FSK output - it looks like good c4fsk.  But no speaker audio. So now what?

I assume that this app does not read the messages - and then switch to the channel in the message.  So I tuned to a  P25 channel (that is not a control channel).  Since they are only powered when someone has been directed to them - it takes some observing to see the carrier pop up - then fine tune the carrier to the center of the channel.  Then wait until someone shows up on the channel.  When that happens - I get what looks like P25 code - for the 1-5 seconds they are talking - but no audio comes out of the speakers ( I have checked by putting a scope sink on the op25 audio out port - and there is no signal there.).

So am I doing something wrong? I started looking inside the C++ code and spotted the state machine where the go from finding sync (FS) to reading the message.  I'm tempted to put a print statement in there to see if it ever gets the FS word, but I assume its just that I'm doing it wrong.


One of the reasons I want to get this working is to add an adaptive equalization block.  No currently available consumer scanner does well with simulcast P25 systems (where several geographically separated, GPS synced transmitters -  tx the exact same signal - on the same frequency).  This can result in multiple delayed receive signals - which can interfere and cause lost symbols. I believe an adaptive equalizer would fix this problem.


 Rick

As an aside:
 
   1) It took me forever to figure out how to enable the rtl2832 source block (by selecting the block and right clicking) in GR-baz op25.grc.  

   2) I found that "auto-probe" resulting in screwed up performance.  Using the tuner pull down inside the RTL source block, and selecting the DVT e4000 tuner - it worked just fine. 

   3) The rtl source block in gr-baz has a size of 1024*128*2. This resulted in a underflow warning (less data than expected).  I changed the size to 780*128*2 (the amount being received - as printed in the warning), and the warning went away.

[richard kellogg]

I finally got the op25.grc from gr-baz block to work.

Apparently a new version of the underlying gnuradio code broke his op25 application. 
Instructions for patching it are here http://wiki.spench.net/wiki/OP25.  I only found this via his twitter

@spenchdotnet

Following these instructions was not easy for me (limited linux knowledge) - he assumes you know what you are doing. But after a bit, I was able to get it to compile/work.

One thing I must say for the OP25.grc application - I had to make some changes to get it to work.

I had to change the default sampling of the RTL from 250 kHz to 1.2288 MHz. and I changed the decimation to 32, and the number of samples per symbol from 6 to 8.  The FM audio then is 38.4kHz.  Doing this - the DIBITS display shows 4 obvious lines for the C4FM decode. With the original op25.grc settings (enabling the RTL source, selecting the E4000 tuner, and changing nothing else) - the DIBITS display did not show 4 lines - but random dots.

Anyway I'm happy now - and would like to thank all of those who labored on op25.

[Cipyz]

richard can you help me please with my problem?

 

please email me at ciprian_z...@yahoo.com

 

BEST REGARDS!

[matt d]

Anyway I'm happy now - and would like to thank all of those who labored on op25.

Hello Richard!  I have been trying for a while to get OP25 running but i have met no success.  Did you have to disable a bunch of blocks?  I did to get it to run.  if I dont disable the 'wx gui fft sink' then it dies with this error:

Imported legacy fsk4
Using Volk machine: ssse3_32
Traceback (most recent call last):
  File "/home/matt/Spench.net examples/OP25/op25_grc.py", line 612, in <module>
    tb = op25_grc()
  File "/home/matt/Spench.net examples/OP25/op25_grc.py", line 279, in __init__
    self.wxgui_fftsink2_0_0.set_callback(wxgui_fftsink2_0_0_callback)
  File "/usr/local/lib/python2.7/dist-packages/gnuradio/gr/hier_block2.py", line 54, in __getattr__
    return getattr(self._hb, name)
AttributeError: 'gr_hier_block2_sptr' object has no attribute 'set_callback'

Have you seen this error?

I am using ubuntu 12.10 with GNUradio 3.6.3.   i too used the build script from spench.net but the OP25 build script has a broken link in it so i had to build OP25 from source.  i didnt install gr-baz but somehow i have the gr-baz files here.  how did you install gr-baz?   I have yet to see the OP25 python gui start up.  any tips or hints will be much appreciated.

[Darrin Pearce]

Hi Richard

Also struggling through this as well. Nearly there, just need to fine tune the configuration. I'm wondering if you could post your GRC file for the forum?. Cheers Darrin

[Brad Richardson]

 I just installed Ubuntu then GNU Radio now I am trying to get the OP25 block to show up in the companion. This is where I am at so far.

Writing out env...:

PyBombs.sysutils - INFO - To set up your environment (in bash) run: "source cd pybombs/setup_env.sh"

brad@ubuntu:~/pybombs$ source cd pybombs/setup_env.sh

bash: cd: No such file or directory

brad@ubuntu:~/pybombs$

I am also trying to figure out how to run Open Bts with no luck

[Doug Hutton]

I have been building an Ubuntu - GNUradio system like the rest of y'all and, thanks to these postings, have had some success.

I made an Ubuntu system at 14.04, downloading the  .iso  from the Ubuntu site and making an install DVD. No problems.

I used the 1st  wget  from   http://wiki.spench.net/wiki/OP25_How_To_Build   to build GNUradio.  It ran for 1.5 hours and worked just fine.  I think the release it built was 3.7.4 and it works just fine with all the new blocks.

Now, I have a late, stable, GNUradio system and just want to install OP25 and have it work just as slick as the first two installations.
However, the  2nd wget from spench -
wget http://wiki.spench.net/files/build-op25 && chmod a+x ./build-op25 && ./build-op25 -v all

failed because of changes to files and the instructions at    http://wiki.spench.net/wiki/OP25    beginning at  Latest  are 'way too vague for me.  If only someone could build a new wget process that installs OP25 with GNUradio 3.7.4, we would have a simple, 3-step process that avoids most of the trauma that you have to go thru to use SDR.

I'm almost there.  Can someone help?

Doug
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[grege...@gmail.com]

Hello to everyone that has been struggling to build and use OP-25.  I have been banging my head against it for two weeks, scouring the Internet for instructions, looking for clues in YouTube videos, doing clean installs of various distros, etc.
I finally found a thread on radioreference.com that got me up and running.

HERE IS HOW YOU DO IT

1.  Forget all about build scripts from spench, marcus leech, etc.  They have all been broken/superseded by the newest releases of gnuradio and op25
2.  Forget about separately installing gr-baz or gnuradio-companion (grc).  You will not be running op-25 as a flow graph.
3.  I strongly suggest that you start with a clean install of Ubuntu 14.04.1 or Linux Mint 17.1, 64 bit, on a quad core machine with at least 4 GB of RAM.
4.  Do all of the OS updates, but DO NOT install gnuradio or any related components from the package manager.
5.  Go to www.radioreference.com, go to the forums tab, go to the software defined radio forum, find the thread "Virtualbox Project-Run OP25 on Windows 7" 
6.  In this thread, member PiccoIntegra explains in detail how to install gnuradio, op-25 and all dependencies with pybombs, the current correct method.  Follow his instructions posted 11-08-2014 EXACTLY.
7.  In a later post on 11-19-2014 PiccoIntegra explains exactly how to launch and use op-25.  Note that the actual app is called scope.py and it is buried deep in a sub folder.  You have to set the source each time you open a terminal window $ source ~/target/setup_env.sh
and you have to navigate to the app folder $ cd pybombs/src/gr-op25/op25/gr-op25_repeater/apps
8. launch with ./scope.py plus all the arguments for your equipment and setup.  Read the entire thread for examples and also check out http://op25.osmocom.org/trac/wiki.png/wiki/SignalScopePage