Hi Josh, Thanks for your kind reply. The figure is shown in http://dl.dropbox.com/u/39710586/rfx2400_sample.png .
I guess it is not caused by Tx transient, because: 1) The TX N210 is just dedicated to TX path in my application, and thus does not have Tx/Rx switch capability; 2) I have used XCVR2450 to receive sampled data (uhd_rx_cfile.py) with the same tx setup (Tx uses RFX2400), but there is no such high noise. Maybe I should switch to the usrp-user mail-list? Regards, Lizhao 2012/9/19 Josh Blum <j...@ettus.com> > > > On 09/18/2012 09:27 AM, You Lizhao wrote: > > Hi All, > > > > I have used RFX2400+N210 to sample real-time OFDM signal, and found that > > there are two suspicious noises, which are shown in attachment or > > http://uploadpie.com/vcX3j . > > > > One suspicious noise appears at the start-up stage of N210, and the other > > suspicious noise appears at the end of a packet. The unwanted noise may > > ruin my ofdm_sync algorithm. So I am wondering that is it possible to get > > rid of these noises? How do they come? > > > > BTW, I use GNURadio v3.6.3 and UHD driver cloned at Sep. 11. Any comments > > are appreciated. Thanks! > > I couldnt see the upload pie link. Perhaps you are seeing transients > when TX stops. I guess I have 2 suggestions: > > 1) make sure you are ending the transmit burst with the EOB tag > > http://gnuradio.org/cgit/gnuradio.git/tree/gr-uhd/include/gr_uhd_usrp_sink.h#n59 > http://gnuradio.org/cgit/gnuradio.git/tree/gr-uhd/examples/c++ > > 2) Also its good to pad out the burst/ofdm frame to push the frame > through the TX DSP filters, and also to mitigate transients. > > -josh > > > > > > > Regards, > > Lizhao > > > > > > > > _______________________________________________ > > Discuss-gnuradio mailing list > > Discuss-gnuradio@gnu.org > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >
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