Spectra Precision Survey Pro v3.80 Recon GPS User Manual - Manual (Page 13)

GPS Coordinates
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ECEF XYZ
Geodetic coordinates are some times given in the Earth Centered
Earth Fixed (ECEF) Cartesian coordinate system. This coordinate
system has its origin at the Earth’s center of mass, the primary (Z)
axis is the earth’s spin axis; the secondary (X) axis is the intersection
of the equatorial plane and the mean meridian of Greenwich; the
tertiary (Y) axis is orthogonal in a right handed system. An ECEF
XYZ coordinate can be converted into the corresponding lat, lng, ht
using standard formulas.
For many surveying applications, the horizontal and vertical
coordinate systems are separate. Below are descriptions of common
horizontal and vertical coordinate systems used in surveying and
mapping.
Fig. 2: Earth Centered Earth
Fixed Geodetic Coordinates
G
re
en
w
ic
h
M
er
id
ia
n
Equator
φ
λ
X
Z
Y
h
z
y
x