Re: [Discuss-gnuradio] Simulation inconsistent (Time interleaving block)

[Martin Braun]

On Fri, Jul 08, 2011 at 05:57:17AM +0000, Höin Michael (hoim) wrote:
> Hi all
> 
> I have a simulation problem with my time interleaving block. If I simulate my 
> block the most time all tests get passed, but in average every 7th simulation 
> the tests don't pass and I get the message:
> 
> Traceback (most recent call last):
>   File "./qa_howto.py", line 239, in test_007_time_interleaving_vff
>     self.assertFloatTuplesAlmostEqual (expected_result_0, result_data0, 6)
>   File "/usr/local/lib/python2.6/dist-packages/gnuradio/gr_unittest.py", line 
> 85, in assertFloatTuplesAlmostEqual
>     self.assertEqual (len(a), len(b))
> AssertionError: 86016 != 80640
> 
> Had somebody in the past the same problem? I have no idea what the fault 
> could be.
> Any idea? Any help will be appreciated.

Hi Michael,

are you using free-running simulations, e.g. by reading from a file and
without any kind of throttling? If so, try adding a throttle and see
what happens.
Note that if this helps, then there's probably a bug in GNU Radio
(assuming you've tested the hell out of your own code). I've seen flow
graphs randomly produce signal processing errors when run without any
kind of throttle (in particular, when running unit tests from large
pre-recorded IQ-files), but so far I haven't been able to cook up a test
scenario with which this could be properly tested.
However, whenever I've taken my code to the antenna where the USRP
limits the incoming data rate, these errors have vanished.

MB

-- 
Karlsruhe Institute of Technology (KIT)
Communications Engineering Lab (CEL)

Dipl.-Ing. Martin Braun
Research Associate

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KIT -- University of the State of Baden-Württemberg and
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