[LEAPSECS] LOD reaches 0 s/d

Joe Gwinn gwinn at raytheon.com
Mon Jan 4 15:58:39 EST 2021


I have, a full-scale test on a large radar system probably fifteen years ago.  

The usual positive leaps (a second inserted) caused some disturbances, but not large.  Negative leaps (a second deleted) caused some gyration, but no crash.  

Insertion and deletion was accomplished by manually commanding time to jump while running a standard heavy-load scenario in simulation on the actual radar.  The simulation part is that a synthetic sky is generated to exercise the radar hardware and software.

The primary issue is that the radar tracker is physics based, and really objects to step discontinuities in time, where timestamp differences do not yield the true elapsed time intervals.

Joe Gwinn


-----Original Message-----
From: LEAPSECS <leapsecs-bounces at leapsecond.com> On Behalf Of Poul-Henning Kamp
Sent: Thursday, November 12, 2020 6:46 PM
To: Leap Second Discussion List <leapsecs at leapsecond.com>
Subject: [External] Re: [LEAPSECS] LOD reaches 0 s/d

--------

>     predicts that d(UT2)/d(TAI) = 1 after 2021-11-13, ie
>     the rates of UTT2 and TAI are expected to agree for the
>     next year. This has never happened since 1961. We may
>     not need to abolish leap seconds for quite a while.

Unless of course we get close enough to a negative one, that people are *really* going to freak out.

Hands in the air:  Who here besides Warner and me has ever tried to test handling of negative leap-seconds ?

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.
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