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Re: [Discuss-gnuradio] benchmark_* not working correctly

From: Tim Meehan
Subject: Re: [Discuss-gnuradio] benchmark_* not working correctly
Date: Sun, 30 Sep 2007 15:05:45 -0700

Dev, Johnathan and All,

After re-reading Dev's emails about 64 vs 32 bit and realizing that gr_mpsk_receiver_cc.cc has not changed in some time, I took another look at this.

On my build gr_fir_ccf->filter() was not functioning properly.  This is called be the gri_mmse_fir_interpolator from gr_mpsk_receiver_cc. Note that my build was using the _simd code. 

The symptom was the interpolator was returning the real part of one sample with the imaginary part of another sample.  This explains why my earlier "patch" appeared to "fix" the problem.

My final solution was to do a make clean and configure with
./configure --with-md-cpu=generic
this forced the use of the *_generic instead of the *_simd

With this change ./benchmark_loopback.py seems to  work with
-m dqpsk
-m dbpsk

I have not spent any time looking into why the *_simd code did not seem to work. 


On 9/28/07, Tim Meehan <address@hidden> wrote:

Dev,  Johnathan, and all

After spending some time looking through gr_mpsk_receiver_cc.cc I am not sure how this
ever worked.  Below is a patch that works for me.  There are two minor changes

1) I did not understand how the delay line for the interpolator could work as coded so I changed it to what made sense to me.

2) I changed the sign of the return value on the phase_error_detector.

Let me know if this patch works for you. 


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