[time-nuts] HP 58503A

[Doug Reed]

OK, that's what I get for working from memory. :-)
I got the idea more or less right but it has nothing to do with the 
abbreviation under discussion....
Thanks for the correction.
73, Doug.

bg at lysator.liu.se wrote:
> Doug,
>
>> I ran into a wiki description of GPS using WGS84 a couple days ago. It
>> included a mention of ESEC and it was something like: Earth Static,
>> Earth Centric. I think I was following a link about the Z3801A.
>>
>> It referred to the fact that lat-lon is referenced to a static grid on
>> the Earth and doesn't change as the Earth rotates on its axis or around
>> the sun. Earth static and Earth centric.
>
> That reference frame is called Earth Centered Earth Fixed  (ECEF). And
> that is what GPS is using "internally". However it is not lat/lon/h, but
> cartesian with origo in the earth center, xy in the equatorial plane and z
> pointing towards the north pole.
>
>      http://en.wikipedia.org/wiki/ECEF
>
> --
>
>     Björn
>
>