Re: [Discuss-gnuradio] problem with ofdm link

[Martin Braun]

Alphonso,

looks like you've found a bug! Here's how I debugged this (it's a good
and easy learning example):

- Build GNU Radio w/ debug symbols
- On my system, I need to allow core dumps: Run `ulimit -c unlimited`
- Then run the app, it'll produce a file called `core`
- Open that with gdb: gdb /usr/bin/python core
- In the gdb command line, run `bt`

It'll show you it crashed on line 186. As you can see, the code makes
the assumption that d_pilot_carriers is populated, which it isn't --
there's your bug!

Do you want to submit a fix?

M

On 19.06.2015 07:04, address@hidden wrote:
> hi martin,
> i have read the manual page for the ofdm_carrier_allocator from [0] and
> the ofdm introduction from [1]. i have also downloaded your examples
> from [2].
>  
> i am testing now with this flow graph (my_graph.png). input is a vector
> source with this repeating vector:
> (1+1j, -1+1j, -1-1j, 1-1j, -1+1j, -1-1j). as mentioned in the previous
> posts the first part (until stream_to_tagged_stream and the sinks) works.
>  
> the structure of my occupied carriers (my_carriers.png) are the same as
> yours (martin_carriers.png) apart from the length and the pilots. i have
> even tried it with the range command (my_range.png).
>  
> nothing works. the error "floating point exception" still remains.
>  
> now i am more confused as before. i am sure it is some stupid
> mistake/error and very simple but i can't figure it out.
>  
> every help is appreciated!
> thanks!
>  
>  
> alphonso
>  
>  
> [0]
> http://gnuradio.org/doc/doxygen/classgr_1_1digital_1_1ofdm__carrier__allocator__cvc.html#details
> [1] https://gnuradio.org/doc/doxygen/page_ofdm.html
> [2]
> http://gnuradio.org/redmine/projects/gnuradio/repository/revisions/master/show/gr-digital/examples/ofdm