ashtech DG16 Reference Manual page 101

The generic formula used to translate and rotate from coordinate system 1 to
coordinate system 2 is as follows:
where =
e e
rx x
Example: Define local datum as the WGS-72 datum
Send the following commands to the receiver:
$PASHS,UDD, 0,6378135.0, 298.26,0,0,4.5,0,0,-0.554,0.23
$PASHS,DTM,UDD
This implements the transformations listed in Table 5.2 and below.
Table 5.2. Ellipsoid Parameters for WGS-72 and WGS-84
Datum
WGS-72
WGS-84
Dx=Dy=0
Dz= 4.5 meters
-6
m= 0.23 x 10
e =e =0
x y
e
= –2.686 x 10
z
in the following equation:
x 0
=
y 0
z WGS84 4.5
After issuing the $PASHS,DTM,UDD command, the receiver internally transforms
positions from the reference datum (WGS-84) to the user-defined datum. In
standard text books, however, the datum transformations are given from local
datums to WGS-84. To simplify entering the transformation parameters, the
translation, rotation, and scale parameters are defined from the local datum to
WGS-84.
Coordinate Transformation
Dx
x
6 –
( ´10
= + 1 + m
Dy
y
Dz
z 2
expressed in radians, similarly for
Reference
Ellipsoid
WGS-72
WGS-84
-6
radians = –0. " 554
– 6
( ´10 )
+ 1 + 0.23
2.686
e e
1 –
rz ry
x
)
e e
– 1
y
rz rx
z 1
e e
– 1
ry rx
and .
e e
ry rz
a[m] 1/f
6378135.0 298.26
6378137.0 298.257223563
6
–
´10
1 – 2.686 0
– 6
´10 1 0
0 0 1
x
y
z 1WGS72
81