ashtech GG Surveyor, Reference Manual

Page: 129 / 256

Command/Response Formats 111
Com
m
and
s
For these parameters to be used, the DTM parameter must be set to ‘USR’.
Example: Define local datum as the WGS-72 datum
$PASHS,UDD, 0,6378135.0, 298.26,0,0,4.5,0,0,-0.554,0.23
$PASHS,DTM,USR
This implements the transformations listed in Table 6.32 and below.
∆
x=
∆
y=0
∆
z= 4.5 meters m= 0.23 x 10
-6
ε
x
=
ε
y
=0
ε
z
= –2.686 x 10
-6
radians = –0. 554
in the following equation:
f5 Rotation in x axis
+ rotation is counter clockwise,
and rotation is clockwise rotation. radians 0.0
f6 Rotation in y axis radians 0.0
f7 Rotation in Z axis radians 0.0
f8 Scale factor. Range -10.00 to
+10.00 ±10 n/a 0.0
Table 6.32: Ellipsoid Parameters for WGS-72 and WGS-84
Datum Reference Ellipsoid a[m] 1/f
WGS-72 WGS-72 6378135.0 298.26
WGS-84 WGS-84 6378137.0 298.257223563
Table 6.31: UDD Structure (continued)
Field Description Range Units Default
x
y
z
WGS 84 –
0
0
4.5
1 0.23
6 –
×
10 +
( )
1 2.686 – 10
6 –
×
0
2.686 10
6 –
×
1 0
0 0 1
x
y
z
WGS 72 –
+ =