Global Positioning System Reference
In-Depth Information
9
GPS OCS monitor station --KaenaPoint, Hawaii
19 July 2004, 0000Z -2359Z
8
7
6
5
4
3
RMS 3D 4 -SV position
error using ORDs :
4.1 meters
RMS 3D 4 -SV position
Error using ERDs :
4.0 meters
2
1
0
0 2 4 6 8 0 2 4 6 8 0 2 4
Time of day (UTC)
Best 4-SV 3D position error -- OCS Hawaii
MS, based on PPS observed range
deviations (ORDs)
Best 4-SV 3D position error -- OCS Hawaii
MS, based on PPS estimated range
deviations (ERDs)
ANALYSIS NOTES
- Best four satellite position solution with 5-degree
mask angle
- Samples taken every minute over 24 hours, with
interpolation for ERDs and ORDs
- Noise injected to emulate specific user receiver
Figure 7.32
Comparison of position errors derived from CS ERDs and ORDs.
Physical environment characteristics: no terrain above the mask angle and no
multipath;
Sampling requirements: once per minute over a 24-hour interval, across a 1º
×
1º equidistantly spaced global grid.
We chose an all-satellite-in-view solution because most receivers built today
employ some form of overdetermined solution that uses more than four satellites if
they are available. A nonaugmented GPS position solution requires a minimum of
four satellites. Since the GPS constellation (as of 2006) provides an average of eight
or more satellites in view at any time, most of the time an AIV receiver will have
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