[time-nuts] Cesium C Field Set?

Poul-Henning Kamp phk at phk.freebsd.dk
Fri Feb 11 08:58:27 EST 2005

In message <420CB2C8.3010909 at erols.com>, Chuck Harris writes:

>As I understand it, the wander is in the GPS satellites, and
>comes from two sources.  The first is doppler shift.  The GPS
>satellites are in motion.  The second is from the DOD's downgrading
>of the GPS system for civilian users.  The way they downgrade
>the system is by adding a random error to the output that varies
>in such a way as to be on a very long term average, correct.

This was the socalled "Selective Availability" and it has been
turned off for several years now.

The main sources of wander these days is ionosphere changes,
tempearture changes at receive location and clock bias in
the satellite (in no particular order).

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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