Hi, I test ftsp alone and find some abnormal skews. One instance is skew of *23% * and the corresponding regression table is: localtime offset 5327769 1120379 5982298 1271252 5888794 1249698 5795290 1228145 5722274 1211314 5608281 1185039 5514777 1163486 5421273 1141932 The regression figure is here<http://www.cs.wayne.edu/xliu/imgs/ftsp_regression.jpg>. Almost every of the 130 nodes is returning skew of 23% !
Another is *183%*, regression table: 1474355 450851 1376050 277030 1327295 -9142 1229783 43734 Any hint on where the issue may arise from, packet-level synchronization or packet timestamping? Thanks for your attention. On Tue, Jul 10, 2012 at 4:29 PM, Eric Decker <[email protected]> wrote: > It is very difficult to tell what is going on from the outside. > > what I've done with complicated situations like this is add > instrumentation (logging) of various state in nodes. > > that is what I would recommend. I don't see anyway around it. > > > On Tue, Jul 10, 2012 at 1:16 PM, Xiaohui Liu <[email protected]> wrote: > >> Hi everyone, >> >> I'm using FTSP of T32khz accuracy (i.e., TimeSync32kC) to synchronize a >> network consisting of 130 telosB motes. Multiple runs are tested and skews >> after synchronization are recorded. In some runs, the skew is incredibly >> large, up to 56%. In others, it is below 0.0045%, which can be regarded >> as normal. Does anyone know what might be causing this issue? One >> observation is that regardless of the skew in a run, all nodes report >> almost identical skews. >> >> Your reply will be greatly appreciated. >> >> -- >> -Xiaohui Liu >> >> _______________________________________________ >> Tinyos-help mailing list >> [email protected] >> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help >> > > > > -- > Eric B. Decker > Senior (over 50 :-) Researcher > > > -- -Xiaohui Liu
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