GNU Radio does not run flow graph

Question

I am sorry but yet again a question about GNU Radio. (I just started following some tutorials a couple of months ago and am learning about it. I am unfortunately not that proficient in it yet, but I am getting there).

Background: So here at the end of the post is my (infamous) FM Receiver flow graph (my hello world in GNU Radio). Nothing has changed. Everything's still as it was (in my first two posts). In fact the problem appears independent of which flow graph I run (as long as it does not contain any bugs), no matter whether I use Qt GUI or WX GUI.

• I upgraded to Windows 10 and also updated to the latest binary (v3.7.13.5/v1.6) for GNU Radio from here.

Problem Observed: The problem is the flow graph appears to start, and stops immediately. No errors. The flow graph window appears, but all I see is the titlebar, and the close, minimize and maximize icons. The rest of the window never appears. The only output I see in the terminal window down in the bottom left corner is the following:

Terminal Log

<<< Welcome to GNU Radio Companion 3.7.13.5 >>>

Block paths:
    C:\Program Files\GNURadio-3.7\share\gnuradio\grc\blocks
    C:\Program Files\GNURadio-3.7\share\gnuradio\grc\blocks

Loading: "D:\projects\gnuradio\projects\FM_RX_1a.grc"
>>> Done

Loading: "D:\projects\gnuradio\projects\AM_RX_1.grc"
>>> Done

Loading: "D:\projects\gnuradio\projects\fm_receiver_qt.grc"
>>> Done

Generating: 'D:\\projects\\gnuradio\\projects\\fm_receiver.py'

Executing: C:\Program Files\GNURadio-3.7\gr-python27\python.exe -u D:\projects\gnuradio\projects\fm_receiver.py

gr-osmosdr 4d83c606 (0.1.5git) gnuradio 3.7.13.5
built-in source types: file osmosdr fcd rtl rtl_tcp uhd hackrf bladerf airspy redpitaya 
[INFO] [UHD] Win32; Microsoft Visual C++ version 14.0; Boost_106000; UHD_3.14.1.HEAD-0-g5491b80e

>>> Done

I also get a ton of warnings when launching the GNU Radio as shown below (I had to remove some lines here as I was hitting the post size limit):

Startup log

setting gnuradio environment
Warning: Block with key "acars2_decode" already exists.
        Ignoring: C:\Program Files\GNURadio-3.7\share\gnuradio\grc\blocks\acars2_decode.xml
.... 
*(a lot of similar lines -> I guess nearly all the blocks/modules in GNU Radio)*
....
Warning: Block with key "zeromq_sub_source" already exists.
        Ignoring: C:\Program Files\GNURadio-3.7\share\gnuradio\grc\blocks\zeromq_sub_source.xml
<<< Welcome to GNU Radio Companion 3.7.13.5 >>>

1. I thought maybe it is some permissions problem. I tried launching GNU Radio as administrator (just to test).

   • GNU Radio just failed to start.

2. Anyways, as always, the Dongle works. I compared it, by running CubicSDR.

3. After I had posted this question on HAM.SE, I downgraded to version 3.7.11.1 from here and it was able to launch the Flow graph.

   • Even though, only Qt GUI worked. When a flow graph made with WX GUI is run, it would start a little and then the window would freeze. Which is strange. As with this GNU Radio version, this flowgraph used to work on Windows 8.1.

4. Then after @MarcusMüller hinted that I may possibly have two GNU Radio installations [possibly conflicting with each other],

   • I removed the GNU Radio version 3.7.11.1,
   • restarted the computer
   • and thoroughly checked that there are no GNU Radio installations anywhere.
   • I reinstalled the latest version of GNU Radio 3.7.13.5 and the same problematic behavior was observed as explained above.

What one can see though is that due to some reason (some setting or bug), this version 3.7.13.5 of GNU Radio includes the blockpath twice, as shown below.

<<< Welcome to GNU Radio Companion 3.7.13.5 >>>

Block paths:
    C:\Program Files\GNURadio-3.7\share\gnuradio\grc\blocks
    C:\Program Files\GNURadio-3.7\share\gnuradio\grc\blocks

Loading: "D:\projects\gnuradio\projects\FM_RX_1a.grc"
>>> Done

Loading: "D:\projects\gnuradio\projects\AM_RX_1.grc"
>>> Done

Loading: "D:\projects\gnuradio\projects\fm_receiver_qt.grc"
>>> Done

And from there come all the warnings, I guess. (I have NOT made any such changes. The installation was done with default settings, just like for the other version of GNU Radio v3.7.11.1.

One of the (otherwise working) flowgraphs:

My tentative Conclusion: As far as I can see, the Windows build for GNU Radio v3.7.13.5/v1.6) is buggy here.

Answer 1

I had a similar problem for GRC v3.7.13.5/v1.6 and got it to work finally. The flow graph problem may be because that the RTL-SDR Source can't find the SDR device. I'm using HackRF hardware, and my WX GUI shows up after specifying the index number of the device by adding "hackrf=0" to the "Device Arguments" line in RTL-SDR Source properties. For HackRF, the index can be shown by executing "GNURadio-3.7\bin\hackrf_info.exe" and GRC provides tools for other hardware in the same directory.

If we don't specify the device index number, GRC may not work. The earlier release of v3.7.13.4 outputs error messages for that case but v3.7.13.5 doesn't. The windows build v3.7.13.5 may not be buggy but does not provide adequate messages.

Answer 2

In 3.7.13.5, thanks to Duck Dodgers (I think) who mentioned block paths coming up twice, such as:

Block paths:

C:\Program Files\GNURadio-3.7\share\gnuradio\grc\blocks

C:\Program Files\GNURadio-3.7\share\gnuradio\grc\blocks

I too (after fresh install of 3.7.13.5) got the very long and slow-building text list of 'already exist' warnings, before finally starting up the GNU radio companion window.

So I went into the directory C:\Program Files\GNURadio-3.7\bin to edit the "run_gr.bat" file. I simply commented out the line that has 'set' in it (eg. see below where I added a rem to comment out the 'set' line).

REM --- Set GRC environment ---

rem set GRC_BLOCKS_PATH=%~dp0..\share\gnuradio\grc\blocks

That then allowed the gnu radio companion of 3.7.13.5 to start up without a hiccup at all. Getting no more of those 'already exist' warnings upon startup. All good now. I'm running Windows 8.1 64-bit.

Earlier today, I installed (GR 3.8.1.0 py2.7), which was a total fail. The radio companion window was able to start. But the DOS window indicated some components couldn't be found - and also python 2.7 crash message came up after hitting the 'play' (simulate) button.