Precise Orbit Determination of Global Navigation Satellite System of ...

Chapter 9 Software and Simulation Results
Comparing Figure 9-21 and Figure 9-25 with Figure 9-30 and Figure 9-31, it can be found that the float
ambiguity solution in Figure 9-30 (considering the satellite visibility) is not as good as that in Figure 9-27. When
the tracking station looses the signal from the satellite, in the software GEOKAL, the initial ambiguity will be set
to zero; when the signal is re-locked, the ambiguities are solved again. The same true ambiguities will be set
before and after observation interruption. This is the reason why Figure 9-30 looks like a bar graph.
Figure 9-32 shows the accuracy of dynamic orbit determination of IGSO satellite at λ=-10° using carrier phase
observation considering the satellite visibility.
Difference (meter)
10
8
6
4
2
0
-2
-4
-6
-8
-10
0 24 48 72 96 120 144 168 192 216 240
Tim e (hour)
Figure 9-32 Accuracy of dynamic Orbit Determination of a IGSO Satellite at λ=-10° with Float Ambiguity Solution
The accuracies of x, y, z coordinates of dynamic orbit determination with float ambiguity solution are ±0.32 m,
±0.34 m and ±0.17 m respectively.
The results of other satellites are as follows.
Ambiguity
21
20.8
20.6
20.4
20.2
20
19.8
19.6
19.4
19.2
19
0 24 48 72 96 120 144 168 192 216 240
Tim e (hour)
Figure 9-33 Float Ambiguity Solution of a IGSO Satellite at λ =20° at Tracking Station 1
128
dx
dy
dz