Hi Harry, You never stop the receiver on node B and C, right? You should not observe anything like that if you do not have dropped packets. Are you using USRP2's?
Miklos On Sat, Nov 2, 2013 at 3:05 AM, Harry Zhang <zhang...@gmail.com> wrote: > Tom, > Thanks for your reply. > I got a weird problem when using rx_time tags. I have three nodes, node > A sends 10 packets within 0.2 sec ,stops for 1sec sends 10 packets , > stops..., sends....,stops.... . Node B and C receive it and record the > receive time using (rx_time+ sample_count*sample_rate). Considerating the > clock offset between B and C, the difference of B and C's receive time must > remain stable. But every time after A stops for 1sec, the receive time's > difference varies several hundreds of microsecond. I'm stumped by this > problem. > Could you give me some advice. Thank you in advance. > > Harry > > 2013/11/1 22:26, Tom Rondeau wrote: >> >> On Thu, Oct 31, 2013 at 3:46 AM, Harry Zhang <zhang...@gmail.com> wrote: >>> >>> Hi, >>> As far as I know rx_time tag is associated with the first sample of a >>> receive stream. If I wanna get multiple rx_time tags while receiving >>> continuous data, should I stop and issue a new stream again and again >>> for getting more rx_time tags. >>> Thank you. >> >> Harry, >> >> We want to minimize tags through the flowgraph since it adds overhead. >> The UHD driver only sends an rx_time tag whenever one is necessary. >> That means that if there is a chance that the host has become >> unsynchronized, it sends an updated tag. So there's one at the >> beginning of the stream to set the initial time. Then, if a dropped >> packet or overflow are detected, it sends a new rx_time tag. >> >> Between time tags, you can count samples and you know the sample rate, >> so you know the time of every sample based on that initial rx_time tag >> (to within the tolerance of the sample clock on the USRP). >> >> Tom >> > > > _______________________________________________ > 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
