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Appendices
Test Bed Receiver Subsystem Addendum – Rev 1 35
PZ90TOWGS84
This command allows the user to input the Helmert transformation relating the GLONASS PZ90 reference frame to the
GPS WGS-84 reference frame. In this case, (x,y,z) is the desired WGS-84 coordinate set and (u,v,w) is the given
coordinate set in PZ90. The transformation is defined by an origin offset (
∆x,∆y,∆z), a linear scale factor (δs) and a series
of small angle rotations (
ε,φ,ω), given in radians, around the u,v and w axes respectively. By default, the values are set to
those published by Misra et al. (ION GPS 96, pg 307).
There are a number of different transformations that have been published but the majority of them are optimized for the
particular region of the planet that the data was collected in. One of the objectives of the current International Glonass
Experiment (IGE) is to accurately determine a PZ90 to WGS-84 transformation that is consistent on a global scale.
The PZ90TOWGS84 command can be used in conjunction with the DATUM PZ90 command (see Datum on Page 26) to
allow for position output in a user-defined PZ90 frame.
The relevant parameters for the PZ90 ellipsoid are from the GLONASS Interface Control Document (ICD) version 4.0,
1998 Coordination Scientific Information Center (CSIC). Please see the following table for the reference ellipsoid
constants.
ELLIPSOID a (metres) 1/f f
Parameters of Earth 1990
6378136.0 298.257839303 0.00335280374302
Syntax:
PZ90TOWGS84 option [∆x] [∆y] [∆z] [δs] [ε] [φ] [ω]
Options:
ARGUMENT DESCRIPTION
DEFAULT
Set to default Helmert transformation parameters
SET Set to user specified values (all must be specified, see the following section of this table)
PARAMETER DESCRIPTION
∆x
Origin offset in x direction [m]
∆y Origin offset in y direction [m]
∆z Origin offset in z direction [m]
δs Scale factor given in parts per million (ppm), final linear scale factor given as (1 + δs*10-6)
ε
Small angle rotation around u axis [arcsec]. A posi
tive sign for counter clockwise direction and a negative sign for
clockwise direction taking into consideration that the trasformation is going from PZ90 to WGS84.
φ
Small angle rotation around v axis [arcsec]. A positive sign for counter clockwise direction and a negative sign for
clockwise direction taking into consideration that the trasformation is going from PZ90 to WGS84.
ω
Small angle rotation around w
axis [arcsec]. A positive sign for counter clockwise direction and a negative sign
for clockwise direction taking into consideration that the trasformation is going from PZ90 to WGS84.
Example:
PZ90TOWGS84 DEFAULT
PZ90TOWGS84 SET 0.1,0.4,-0.3,6,0,0,4
NOTE: The format and sign conventions in this command are set up to conform to the given reference and differ from
the NovAtel USERDATUM command.