I have two questions.

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

  I have two questions.

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 > >

  I have two questions.

Hello All, Just want to note that NI 2921s use XCVR2450, which is half-duplex (cannot rx and tx concurrently). B210s will work better, as they are full-duplex 2x2 MIMO. Regards, Kyeong Su Shin On Wed, Aug 30, 2017 at 8:44 PM, Michael Don via USRP-users < usrp-users@lists.ettus.com> wrote: > > 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 >> >> > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > >