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Re: [Discuss-gnuradio] benchmark_xx.py not consistent output

From: Tom Rondeau
Subject: Re: [Discuss-gnuradio] benchmark_xx.py not consistent output
Date: Fri, 7 Sep 2012 10:24:30 -0400

On Fri, Sep 7, 2012 at 12:28 AM, Qing Yang <address@hidden> wrote:
> Hi,
> I don't think it is the problem of channel since your channel is symmetric.
> Perhaps you could check your parameters first and list the commands you used
> to the mailing list. Usually I use benchmark in /gr-digital/examples/ofdm
> and it works well.
> BTW, your gmail account is some kind of cool ...
> --
> Yang, Qing
> Information Engineering, CUHK
> 2012/9/7 usrp n210 <address@hidden>
>> I am using 3 USRPs (USRP N210 ).
>> I run example program "benchmark_rx.py " and "benchmark_tx.py " in
>> /gr-digital/examples/narrowband/.
>> I performed experiment on 2 USRP's(A,B) at a time.
>> so A-B and B-A 2 channels for 2 USRP.
>> when I send packets from A-B "psk" modulation scheme gives best(171/171)*
>> performance while same is not true for B-A(171/0)*.
>> while "gfsk" scheme gives good performance from B-A(171/171)*.
>> Can anybody knows why different modulation scheme gives different result
>> on different channel ?
>> Is it related to USRP synchronization ?
>> Can we perform packet level debugging in USRP ?
>> How can we find the cause of this problem ?
>> Or is it implementation related bug in GNU-radio?
>> * : (n_rcvd/n_right) n_rcvd => received packet,n_right => correct received
>> packet

Try adjusting the frequency to make sure both USRPs are as close as
you can get them by eye. What you are seeing is probably something to
do with the signal being outside the channel and you aren't able to
bring it back in on one side while the other side is. I'm not entirely
sure why that might happen, but I've seen it before.


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