Rtk

1 cmb

2 cmb

Network-based RTK

5 mmb

10 mmb

a According to the WAAS specifications; however, much better accuracies (<2 m, even up to 30-70 cm) were reported, as explained in Section 9.7.2.1. b Increases with the baseline length.

a According to the WAAS specifications; however, much better accuracies (<2 m, even up to 30-70 cm) were reported, as explained in Section 9.7.2.1. b Increases with the baseline length.

• Horizontal service availability:

• Requirement—95 percent threshold of 13 m, 99 percent of the time or better

• Vertical service availability:

• Requirement—95 percent threshold of 22 m, 99 percent of the time or better

• Requirement—6 m or less, constellation average

Other factors affecting the GPS positioning accuracy depend on (1) whether the user is stationary or moving (static versus kinematic mode), (2) whether the positioning is performed in real time or in postprocessing, (3) the data reduction algorithm, (4) the degree of redundancy in the solution, and (5) the measurement noise level. The currently achievable GPS accuracies, provided as two-sigma, corresponding to 95 percent confidence level, are summarized in Table 9.6. The lower bound of the relative positioning accuracy listed in Table 9.6 cannot be stated with precision, as it depends on several hardware and environmental factors, as well as the survey geometry, among others (the symbol ^ indicates the increase of the values listed). Thus, the accuracy levels listed in Table 9.6 should be understood as the best achievable accuracy.

0 0

Post a comment