Re: [Discuss-gnuradio] USRP1 can't correctly receive packet from USRP2 using benchmark_tx/rx or benchmark_ofdm_tx/rx

[Josh Blum]

You could be running into the issue of frequency offset between the LO's 
of the two usrp devices. Try increasing the rate so the symbols are 
wider spectrally to make up for the offset. I believe that its the -r 
option.

Hope that helps,
-Josh

On 05/18/2010 06:54 PM, Fisheep wrote:
> Hi,
>
> I have currently set up a transmission between USRP1 and USRP2 with FLEX900.
> And got the following results.
>
> In gnuradio/gnuradio-example/python/digital/
> Successful transmission (ok = True) when
>    Tx (USRP1) : ./benchmark_tx2.py -f 900M --tx-amplitude=0.4 -m dbpsk2
>    Rx (USRP2) : ./benchmark_rx2.py -f 900M -m dbpsk2 -e eth0
> Fail (ok = False and lost lots of packets) when
>    Tx (USRP2) : ./benchmark_tx2.py -f 900M --tx-amplitude=0.4 -m dbpsk2 -e
> eth0
>    Rx (USRP1) : ./benchmark_rx2.py -f 900M -m dbpsk2
>
> In addition, if using the original modulation like dbpsk not dbpsk2, the
> transmission also not work as expected.
>
> also ref to the two discussions:
> http://www.ruby-forum.com/topic/203035
> http://www.ruby-forum.com/topic/202105
>
> I successfully transmit packet from USRP1 to USRP2 with the following
> parameter setting.
>    Tx (USRP1) : benchmark_ofdm_new_tx.py -f 900M --tx-amplitude=0.4 -i 128
>    Rx (USRP2) : benchmakr_ofdm_new_rx.py -f 900M -d 100
> But the same problem as above, USRP1 can't receive correct packet from
> USRP2.
>
> Does anyone has any suggection about this problem, please let me known,
> Thanks.
>
> Sincerely,
> Fisheep