[time-nuts] Lost GPS lock or 1PPS recently?

Dr. David Kirkby drkirkby at kirkbymicrowave.co.uk
Thu Sep 6 11:30:38 EDT 2018

On Tue, 4 Sep 2018, 18:35 John Sloan, <jsloan at diag.com> wrote:

> Folks:
> Yesterday (2018-09-03) afternoon (about 22:00UTC, 16:00MDT) I noticed one
> of my three home-made GPS-disciplined NTP servers had lost its GPS lock.
> After some forensics on my part, this (2018-09-04) morning (about 16:00UTC,
> 10:00MDT) I replaced the amplified antenna, and the device reacquired its
> lock. I figured it was just an antenna failures; this is an amplified
> filtered antenna so it has active electronics.
> Then just an hour or so later, I noticed one of my commercial
> GPS-disciplined NTP servers (TimeMachines) had lost the GPS 1PPS timing
> signal, but indicated it still had GPS lock. (I
> No clue what's going on in my suburb near Golden Colorado. But I’m a
> little freaked out. Trying to figure out which rule, [1] It’s something
> stupid I’ve done, or [2] I am not unique, to apply.
> :John

I know someone else who had a similar problem. It turned out to be a fault
in one of the active antennas which went into self-oscillation,  which
jammed the other GPS receivers.


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