Reliable Carrier Phase Positioning

Preface Currently, the Global Navigation Satellite Systems (GNSS) GPS and GLONASS are modernized and new GNSS such as Galileo and Compass are developed. The modernization of GPS includes an additional signal on L5 which lies in an aeronautical band. This will enable a dual frequency positioning on board an aircraft and an elimination of the dispersive ionospheric delay, which is one of the largest error sources for current single frequency receivers. Dataless pilot signals will be introduced on all GPS frequencies which will enable a longer integration time and faster signal acquisition. Moreover, the Multi-plexed Binary Offset Carrier (MBOC) modulation will be used on L1. Galileo uses larger signal bandwidths than GPS, which will substantially reduce the code tracking error and improve the positioning accuracy. For example, the Alternate BOC modulated E5 signal has a bandwidth of 92.07 MHz, which enables a five times lower code tracking error than the BPSK(10) modulated GPS L5 signal. The additional frequencies and new signals will improve the estimation and elimination of ionospheric delays, which is one of the major error sources for positioning. The GPS and Galileo satellites transmit spread spectrum signals that enable a positioning accuracy of 1 m. A significantly higher positioning accuracy can be achieved with the carrier phase which can be tracked with millimeter accuracy. However, the carrier phase is period and requires the resolution of an integer ambiguity for each satellite. The reliability of this integer ambiguity resolution was so far limited by the small carrier wavelength of 19.0 cm, receiver and satellite biases, multipath and a large number of unknown atmospheric delays, which result in an ill-conditioned equation system and a probability of wrong fixing of a few percent. This thesis provides new algorithms and methods to reduce the failure rate by more than seven orders of magnitude. The key to reliable integer ambiguity resolution are multi-frequency linear combinations that eliminate the ionospheric delay, increase the wavelength to more than 3 m and keep the noise at a centimeter level. There exist two further challenges for carrier phase positioning that are addressed in this thesis: one is a continuous tracking of the carrier phases in environments with strong multipath and/ or during ionospheric scintillations, and the second one is a precise estimation of both receiver and satellite phase biases. The first chapter gives an intuitive introduction to the suggested methods for reliable integer ambiguity resolution. Moreover, the …