[time-nuts] Positional accuracy of the M12+T
bg at lysator.liu.se
bg at lysator.liu.se
Wed Jan 3 08:01:55 EST 2007
On Wed, January 3, 2007 13:40, Stephan Sandenbergh said:
> The datasheets mention <25m SEP (haven't got a clue what 'SEP' stands for)
> positional accuracy. However, I am sure this is relative to the actual
> datum. Does anyone know where I could find information on relative
> positional accuracy within multi channel common view configurations?
GPS have strange error metrics, Spherical Error Probability, iirc is 50%
of the 3d positions within a sphere with a radius (diameter?) of 25m.
Maybe the metrics come from the military "background" of GPS. SEP says
nothing about gaussian error distribution and 50% is even less than 1
sigma, whatever that says.
Hmmm... with 25m position accuracy (and 100ns is about 30m), how do they
really get time down to a few ns. Clever engineering! :-)
--
Björn
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