Hi Eric, 2010/2/12 Eric Blossom <e...@comsec.com>: > On Fri, Feb 12, 2010 at 12:52:00PM -0800, Veljko Pejovic wrote: >> Hi, >> >> I'm using two USRP2 with XCVR2450s, gnuradio 3.2.2 and Ubuntu 9.10. >> >> I ran the benchmark_tx/rx example from gnuradio-examples/ofdm and >> measured packet inter-arrival times at the receiver. I also modified >> the sender to wait for some time (like 200ms) between individual >> packets. I also set the msg queue size to one. In python code I'm >> printing a bunch of time.time() values to keep the timeline of the >> events. >> >> What I observe is the following: >> - inter-departure times are constant, the packet size and the bit rate >> would of course influence the time spent sending, but that would still >> be a relatively small value. >> - at the receiver, most packets are received with the inter-arrival >> time comparable to the inter-departure time at the sender, however, >> occasionally I would see a huge lag between two consecutive packets >> (almost a second). >> >> I read the NSDI'09 paper >> (http://portal.acm.org/citation.cfm?id=1558984) that talks about USRP1 >> performance, however, what I observe is way higher delay and it's >> USRP2. Thus, I'm sure that there's something I can do to fix this >> delay. Any hints? > > Are packets getting dropped?
I don't get any overruns/underruns reported, but, yes, there's some packet loss. However, I'm only considering the interarrival time of those packets with consecutive packet numbers. > Is the USRP2 on a dedicated ethernet port? yes, it is. > Is there a switch between the host and the USRP2? no > > Eric > cheers Veljko _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
