On Tue, 19 Nov 2013 08:51:32 -0500, [email protected] wrote: (time-nuts Digest, Vol 112, Issue 59) > Message: 1 > Date: Tue, 19 Nov 2013 13:17:26 +0200 > From: Stephan Sandenbergh <[email protected]> > To: Discussion of precise time and frequency measurement > <[email protected]> > Subject: [time-nuts] Strange 100ns jumps on Motorola M12+T > Message-ID: > <cadbj3vzgfbnbzl-vkhjmfzn4mkopgni9fgxahlfxbqodbo3...@mail.gmail.com> > Content-Type: text/plain; charset=UTF-8 > > Hi, > > I've recently measured the 1PPS outputs of three Motorola M12+T GPS > receivers using two HP53131A TICs. Antennas are located next to one another. > > Now I notice the one M12+T has changed its time offset by 100ns three times > over the period of 48hrs. The jitter remains the same, only the offset that > changes. > > I'm currently having a re-run of the measurement. But, in meanwhile, has > anyone seen this kind of behaviour? A firmware issue perhaps?
I've seen this in old Symmetricom GPS receivers. The 100ns jumps occur when lock is lost or gained, which is typically caused by the presence or absence of at least one good-enough satellite in view. A bad connection in the antenna path is one cause. Interference can also provoke the effect. Joe Gwinn _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
