Re: [Discuss-gnuradio] Problem feeding garbage to GNU Radio

[Eric Blossom]

On Sat, Oct 11, 2008 at 01:04:55PM -0400, Philip Balister wrote:
> On Sat, Oct 11, 2008 at 12:06 PM, Eric Blossom <address@hidden> wrote:
> > On Fri, Oct 10, 2008 at 02:59:33PM -0400, Philip Balister wrote:
> >> I'm working on a flow graph that reads samples from a file and feeds
> >> them to the wfm demod block. I managed to get this working, but along
> >> the way I ran across a problem ....
> >>
> >> My data file is 16bit complex shorts in big-endian format. It looks
> >> like the file source block reads data from the file and sends it to
> >> the fm demod which is expecting a complex float data. I attempted a
> >> quick test by using the original data file (wrong format) which caused
> >> the flow graph to crash with a seg fault. After converting the data to
> >> a complex float representation the flowgraph works.
> >>
> >> Do people view this as a problem? It seems like the file source block
> >> should attempt  some form of sanity checking on incoming data. If you
> >> aren't expecting a problem, I could see this being hard for people new
> >> to GNU Radio to debug.
> >>
> >> Philip
> >
> > It shouldn't segfault regardless of the input.
> >
> > Can you send or post a link to the flow graph and the test data that
> > reproduces the problem?
> >
> > A gdb stack trace would let us know where it's blowing up.
> > From there the bug should be easy to find and fix.
> 
> I've attached the flow graph.
> 
> The data file is here:
> 
> http://ossie.wireless.vt.edu/~balister/capture/npr_iq_sample.dat
> 
> Right now I'm working through figuring out how many python modules are
> needed to run the flow graph, if I have a chance I'll try and get a
> stack trace. I'm assuming you gsb python and run the flow graph? Arg,

You only need to make a two line change in your code to hookup gdb to
the running python image.  See:
http://www.gnu.org/software/gnuradio/doc/howto-write-a-block.html#debugging

> how do I get the python interpreter to load and run top_block.py .....

See above.

> Philip

Eric