Digital Signal Processing in Global Navigation Satellite and Pseudolite Systems

Abstract

Global Positioning System (GPS) is the main provider of the satellite-based positioning service. While GPS performs very well in outdoor conditions, many people still cannot be located when they are in indoor environment. The main problem this thesis was concerned with is the complex issue of indoor propagation channel characterization in multipath and low CNR (Carrier to Noise Ratio) environment. The objective is to validate a Matlab Simulink model of the acquisition and tracking blocks for a baseband GPS receiver, using the measured signal obtained both via cable and via wireless propagation. The data that is used as input for the modeled receiver was acquired through indoor GPS pseudolite measurement campaigns carried out at Tampere University of Technology in cooperation with some industrial partners. The contributions of the author are the followings: literature studies of current and future Global Navigation Satellite Systems (GNSS) and of GNSS baseband receiver architectures, focusing on acquisition and tracking stage: validation of a Simulink model for the tracking of measured GPS pseudolite signals; estimation of various probability distribution functions regarding the channel parameters and CNR estimation of signal level based on baseband samples. /Kir10