# Re: problem with ofdm link

**URL:** <https://www.ruby-forum.com/t/re-problem-with-ofdm-link/242380>\
**Category:** GNU Radio\
**Created:** [June 19, 2015, 4:06pm UTC](https://www.ruby-forum.com/t/re-problem-with-ofdm-link/242380 "2015-06-19T16:06:07Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![musicdenotation](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ea666f/32.png) [@musicdenotation](https://www.ruby-forum.com/u/musicdenotation)\
**Post date:** [June 19, 2015, 4:06pm UTC](https://www.ruby-forum.com/t/re-problem-with-ofdm-link/242380/1 "2015-06-19T16:06:07Z")

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**Author:** ![unknown](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/u/4bbf92/32.png) [@unknown](https://www.ruby-forum.com/u/unknown)\
**Post date:** [June 19, 2015, 6:33pm UTC](https://www.ruby-forum.com/t/re-problem-with-ofdm-link/242380/2 "2015-06-19T18:33:22Z")

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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