Jakob Jakobsen – Niels Bohr Institute - University of Copenhagen

Jakob Jakobsen

Title: Kinematic GNSS: Ionospheric variations and characteristics of multipath

A thesis submitted September 15, 2010 for the degree of Doctor of Philosophy and defended October 13, 2010.

The Niels Bohr Institute, The Graduate School of Science, Faculty of Science University of Copenhagen Denmark.

Academic advisor:
Carl Christian Tscherning

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Kinematic GNSS: Ionospheric variations and characteristics of multipath

This thesis is focusing on two of the largest factors, which a ect the GNSS signals on their way from the satellite transmitter to the receiver on the ground. This is the variation of the ionosphere and a characterisation of indoor multipath.

It is shown, how singular value decomposition can be used to separate the yearly and daily signal on a computed TEC time series, which locally cover the area of Denmark. Furthermore is it shown, how the analysis can be used to partly generate a local model of the variation of the ionosphere, and partly how the deviations from this model can be correlated with local geomagnetic observations. Thereby make a better foundation for detecting abnormalities in the ionosphere.

Private network RTK services are modelling the ionospheric contribution to GNSS signal over a large geographic area. A new method for evaluation of the service ionospheric modelling performance independent of a rover is presented. Furthermore are a number of dependencies shown for the ionospheric modelling error at an operating network RTK service provider. The dependencies are related to the satellite elevation angle, the distance to nearest reference station, the geographic location in the extrapolation area, and the general daily ionospheric activity.

An increasing number of new GNSS related applications demand positioning and navigation under more and more challenging GNSS conditions, especially indoor. Under these conditions the GNSS signals are heavily a ected and the signal to noise ratio of each satellite link varies, especially under kinematic conditions. The design of a slot car track, which purpose is to control the kinematic behaviour of an object and provide the absolute coordinate to any given instance of time with a great accuracy, is presented in details.

Kinematic tests with this 27m test platform has been performed with two simultaneously cars, attached with a High Sensitivity GNSS receiver. The tests are performed indoor with speeds controlled in the interval of 0.6 to 1.8 m/s. Static tests are performed for comparison reasons. A characteristic of the multipath interference, in form of an analysis of the carrier to noise ratio as well as the in uence in the positioning domain, is given both for the static and the kinematic case.

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