Troposphere Modeling and Filtering for Precise GPS Leveling

Troposphere Modeling and Filtering for Precise GPS Leveling

Kleijer, F.

Teunissen, P.J.G. (promotor)

Aerospace Engineering

2004-04-13

Precise height differences (5--10 mm standard deviation) are of interest for applications such as maintenance of the Amsterdam Ordnance Datum and deformation analysis. For these applications the Global Positioning System (GPS) is a cost-effective alternative for classic leveling techniques. However, the constituents in the troposphere, of which water vapor is both spatially and temporally the most variable component, cause the GPS signals to be delayed. Several types of troposphere modeling are investigated for GPS leveling because the geometry causes the height component to be strongly affected by the signal delays. The dissertation describes physical, functional, and stochastic aspects of this modeling and gives recursive filtering techniques that can be used in the data processing. Static networks or baselines with geodetic receivers collecting two-frequency phase observables were assumed. The most important models and filters are implemented in simulation software with which the sensitivities of the height difference are analysed. By frequent estimation of zenith delays using mapping functions, biases in the filtered height differences can be largely avoided, but the use of spatiotemporal constraints with that turns out to have hardly a positive contribution and can even have a precision-deteriorating effect. A stochastic model for slant delays based on Kolmogorov turbulence shows to be potentially precision improving (10--30% of the standard deviation), but this model is to be validated. Furthermore, the simulations show that, even for observation times longer than three hours, correctly resolving the GPS phase ambiguities has a precision improving effect of 15--20%.

gps
heights
troposphere
filtering

http://resolver.tudelft.nl/uuid:ea1f0cf0-4e48-421b-b7ae-4ae3e36d1880

90-804147-3-5

Institutional Repository

doctoral thesis

(c) 2004 F. Kleijer