Hello Peter, I would think it's related to 1ns per foot, but depends highly on Sat geometry at any given time. I remember talking about this some years ago on time nuts, and someone mentioned it wasn't exactly 1ns/foot, but slightly less (if I remember correctly). Yes, the cable delay is completely independent of the "wobble", since all sat's signals will be delayed equally long. The cable delay just causes a static phase-offset in the UTC 1PPS pulse. This can be compensated for in 1ns steps on our Fury GPSDO. There are some secondary effects such as multipath signals that can also have a detrimental effect on precision, so the antenna quality and it's placement can also help reduce the wobble. The Motorola M12+ manual has some nice explanations and drawings to this effect. I think timing receivers have a much easier time detecting multipath, and rejecting it than 3D fix receivers since timing receivers can over-determine their position/time resolution. bye, Said In a message dated 1/7/2009 08:02:59 Pacific Standard Time, pvi...@theiet.org writes:
Thanks Said. A supplementary question, if I may: can you confirm that the phase "wobble" caused would be a maximum of the usual 1ns per foot? And am I right in thinking that incorrectly specifying the antenna cable delay will only affect the accuracy of the timing of the 1pps output wrt UTC, and not cause any extra wobble? Thanks, Peter _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
