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G GLONASS Commands
G
GLONASS COMMANDS
G GLONASS COMMANDS
G.1 GLONASS-SPECIFIC COMMANDS
This chapter describes MiLLennium-GLONASS GPSCard commands important to GLONASS.
GLONASS-specific commands are generated by using information obtained from the GLONASS satellite system.
Please see the following sections for definitions of these commands.
G.1.1 DGLOTIMEOUT
The differential GLONASS time out (DGLOTIMEOUT) command's function is to set the maximum age of
differential data that will be accepted when operating as a remote station. Differential data received that is older
than the specified time will be ignored.
The ephemeris delay of the reference station is the same as for GPS and can be set using the DGPSTIMEOUT
command (refer to the MiLLennium Command Descriptions Manual for information on this command).
Since there is no Selective Availability (SA) on the GLONASS correction the degradation over time is
considerably less. It could be useful to allow a longer timeout for GLONASS than GPS.
Syntax:
DGLOTIMEOUT delay
Options:
delay: 2 - 1000 (seconds) (default 60)
G.1.2 PZ90TOWGS84
This command allows the user to input the Helmert transformation relating the GLONASS PZ90 reference frame
to the GPS WGS-84 reference frame. The Helmert transformation is defined as:
x
y
z
WGS
Here, (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) given by:
x
y
z
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 "1.6 Datum",
Page 13) 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
82
∆
x
(
δ
=
∆
+
+
∗
y
1
s
10
∆
z
84
0
1
−
=
+
2
5 .
1
9 .
*
10
0
0
WGS
84
ω
−
φ
1
u
)
−
ω
ε
−
6
1
v
φ
ε
−
1
w
−
−
6
1
9 .
*
10
0
u
6
1
0
v
0
1
w
GPS/GLONASS Receiver User Manual Rev 1
PZ
90
PZ
90
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