Hi Rafael, what you're trying to build is not a causal system -- you tell the sink to start transmitting the first sample right at the same moment that your source receives the first sample -- but between that, the samples have to flow through your PC!
Add a bit of delay between rx and tx. Also, what daughterboard are you using? Unless you use one of the daughterboards that support static phase after tuning, and tune as a timed command, the LO phase between the RX and TX will be random [1] Best regards, Marcus [1] http://files.ettus.com/manual/page_sync.html#sync_phase_lo On 06/18/2015 06:47 PM, Rafael Acurcio wrote: > Hello all, > > I'm trying to do ranging using two USRPs N210. > The idea is that the first USRP sends a signal and then the second > USRP recognize it and send the signal back. Looking to the turnaround > time I would be able to know the ranging. > Despite some problems that I already had, right now I'm stuck with the > second USRP. > > To measure the time I'm synchronizing the rx ant tx from the first > USRP using the following code: > > now = self.uhd_usrp_sink_0.get_time_now() > self.uhd_usrp_source_0.set_start_time(uhd.time_spec_t(0.1) + now) > self.uhd_usrp_sink_0.set_start_time(uhd.time_spec_t(0.1) + now) > > Using the fisrt USRP I can do ranging, connecting both (rx and tx) > together, with a good precision. However I couldn't make the second > USRP work yet. When I try to synchronize the tx and rx like I did in > the first USRP I get a bunch of Ls (late packages) in the terminal. > The code drop all the packages. > > My gnuRadioCompanion blocks for the second USRP looks roughly like > > USRP Source -> threshold -> USRP Sink > > There's a better way to solve that problem? > Why do I get the late packages? > > Thanks in advance, > > Rafael. > > > PS: To analyze the data that I'm sending I'm using File Sink block and > analyzing the data after the transmission. > > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
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