I recently purchased two new USRP2 boards each with a XCVR2450 transceiver board. In testing the two boards, I began by conducting a simple tx/rx test in which both boards share a COMMON 10MHz reference clock, as opposed to two independent references. This test was conducted to determine if the measured channel would remain relatively unchanged (time invariant) in a static channel environemnt.
A single 2MHz tone was used as my baseband test signal (no BPSK or QAM). In comparing the baseband tx signal to the baseband rx signal, I noticed that although both signals were 2MHz in frequency, they were out of phase as expected. However, the phase difference was not constant over time. Rather the phase difference was changing over time quite a bit. This occurrence may limit the MIMO capabilities of these boards since the residual carrier offsets must be corrected for individually for each transceiver. Take a 2x2 MIMO system fore example. Four different carrier offsets may need to be corrected rather than one as in the case of a fully coherent system. I'm curious as to whether other users have encountered similar problems with their systems as well, and if so, would be able to explain this occurrence. -- View this message in context: http://old.nabble.com/Transceiver-Residual-Carrier-Offset-tp27424897p27424897.html Sent from the GnuRadio mailing list archive at Nabble.com. _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
