Re: [Discuss-gnuradio] Update: BPSK problem: intermittent inter-symbol interference and phase change

[Cinaed Simson]

On 08/29/2017 04:14 PM, Edwin Li wrote:
> I changed the sample per symbol from 4 to 2, the number of filters in
> rrc filter from 128 to 32, and the intermittent ISI(there is still ISI
> but it is uniform across the packets) and phase change is gone(in
> simulation).
> 
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> I run the program on 2 USRPs, one as Tx one as Rx. The intermittent ISI
> is back. But I suppose it is caused by imperfect timing and frequency
> synchronization.  
> 
>  
> 
> Anyone can comment on this please?

I believe you're were the one reading in a file and writing out a file
and calling it a receiver.

First, I'd disable the correlator, the throttle and the block - which I
don't have - and I can't remember the name - for removing tags.

Add a Channel model before the Polyphase Clock and a CMA equalizer
between Polyphase and the Costa Loop.

Work through tutorial 7.

Then add the correlator at the end the end and see if you can get it to
work.

Before you add back the block for removing tags, you should add a Stream
to Tagged Stream block.

-- Cinaed

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