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Copernicus GPS Receiver 145
TRIMBLE STANDARD INTERFACE PROTOCOL (TSIP) A
Report Packet 0x4A - Single Precision LLA Position Fix
This packet provides current GPS position fix in LLA (latitude, longitude, and
altitude) coordinates. If the I/O Position option is set to LLA and the I/O Precision-of-
Position Output is set to single-precision (all controlled by Packet 35), then the
receiver sends this packet each time a fix is computed. Command Packet 35 controls
position output (XYZ or LLA) and (single or double) output precision. The data
format is shown in below.
The default datum is WGS-84. Altitude is referred to the datum ellipsoid or the MSL
Geoid, depending on which I/O “LLA altitude” option is selected. The time-of-fix is
in GPS time or UTC, depending on which I/O “timing” option is selected. This packet
is also sent at start-up with a negative time-of-fix to report the current known
position. Packet
0x84 provides a double-precision version of this information
C
WARNING – When converting from radians to degrees, significant and readily visible
errors will be introduced by use of an insufficiently precise approximation for the
constant PI). The value of the constant PI as specified in ICD-GPS-200 is 3.1415926535898.
Single precision LLA has a quantization of approximately 2 meters.
Table A.32 Report Packet 0x4A Data Formats
Byte Item Type Units
0-3 Latitude Single radians; + for north, - for south
4-7 Longitude Single radians; + for east, - for west
8-11 Altitude Single meters (HAE or MSL)
2-15 Clock Bias Single meters
6-19 Time-of-Fix Single seconds (GPS or UTC)