[time-nuts] Aircraft ping timing

Poul-Henning Kamp 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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