[time-nuts] Aircraft ping timing
phk at phk.freebsd.dk
Thu Mar 20 12:01:51 EDT 2014
In message <532AE780.4020200 at earthlink.net>, Jim Lux writes:
>On 3/20/14 12:07 AM, Poul-Henning Kamp wrote:
>Is there a document that describes the system somewhere? I've seen
>various descriptions of what's going on. Do they use timing or amplitude
It is a timing measurement and it's not really designed to be precise.
I belive the basic timing accuracy just below +/- 1msec.
As the signal flies, that is +/- 300km.
Projecting that onto the spherical planet, with an antenna angle around
40 degrees smears it out by a factor of roughly 1.5 and that's where
the 740 km comes from.
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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