Читать книгу Global Navigation Satellite Systems, Inertial Navigation, and Integration - Mohinder S. Grewal - Страница 63
2.3.4 Example Calculation of DOPs 2.3.4.1 Four Satellites
ОглавлениеFor simplicity, consider four satellite measurements. The best accuracy is found with three satellites equally spaced on the horizon, at minimum elevation angle, with the fourth satellite directly overhead, as listed in Table 2.1.
The diagonal of the unscaled covariance matrix (H[1]T H[1])−1 then has the terms
where
Table 2.1 Example with four satellites.
| Satellite location | ||||
| 1 | 2 | 3 | 4 | |
| Elevation (°) | 5 | 5 | 5 | 90 |
| Azimuth (°) | 0 | 120 | 240 | 0 |
Typical example values of H[1] for this geometry are
The GDOP calculations for this example are
Gdop.m calculates the GDOP for the chosen constellation for GPS_perf.m by calculating H[1] matrix calcH. See Appendix A on www.wiley.com/go/grewal/gnss.
