USRPs can do Tx and Rx at the same time. I did an experiment where I modified the FPGA image of Node 2 to send the Rx samples directly to Tx on a different freq., and measured the phase difference of the echo from Node 2 at Node 1. I didn't measure the phase difference of the carrier, rather the phase difference of a FM sine signal. Didn't play around with it too much, but I got an accuracy of a few meters, although for some reason I always had to calibrate the system to measure the processing delay. I'd also be interested to see anyone else's results.
-Mike On Wed, Aug 30, 2017 at 8:53 PM, Qasim Chaudhari via USRP-users < usrp-users@lists.ettus.com> wrote: > Hi, > I want to find the distance between two USRPs by sending and receiving > packets (or a continuous wave) in a bidirectional manner. > > Step 1: Node 1 Tx ---------> Node 2 Rx - measures phase, then switches > over to become Tx > Step 2: Node 2 Tx ----------> Node 1 Rx - measures phase and computes > distance. > > I have two questions. > > Q1. If someone else has done/know about this kind of experiment with the > USRP, can you please point me towards some good reference/source/s? > > Q2. When USRP switches from Rx to Tx mode at node 2 (and more importantly, > from Tx to Rx mode at node 1), does it maintain phase continuity of its > local oscillator? (Because otherwise the phase measurements become > meaningless.) > > Currently, I am using NI USRP N2921 with the latest version of GNU Radio > but I can have access to B210s if required. > > Cheers, > Qasim > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > >
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