[Discuss-gnuradio] Update 3: BPSK problem: intermittent inter-symbol interference

[Edwin Li]

Dear mailing list subscribers,

This is an update to my progress on the BPSK ISI problem. Please see the link below for reference.

https://lists.gnu.org/archive/html/discuss-gnuradio/2017-08/msg00305.html

I attached my grc file. I removed the burst shaper block as suggested by Marcus. And the ISI is gone, in simulation, as you can see in the second attachment. I don't know why and I would like to know more about it. Does anyone can share his opinion please?

I tested the program on my USRP X310. Single USRP, tx and rx ports connected by a cable and a 30dB attenuator. The intermittent ISI is there, mocking me, as shown by the third attachment. Because I don't know in the first place what is the cause for this problem, I don't know how to solve it. My USRP is not tuned. Maybe tuning can make a difference? 

Regards,

Edwin

BPSK_packet_simulation.grc
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DownSampledData_simulation.jpg
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DownSampledData_Experiment.jpg
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