| The introduction of the pilot channel in addition to the navigation data is one of the major developments in the modernized GPS and the new Global Navigation Satellite Systems (GNSS). Although both data and pilot channels pass through the same communication channel before reaching the receiver antenna, joint data/pilot processing is often overlooked as it risks compromising the advantages of utilizing the pilot alone. This dissertation identifies and provides a detailed analysis of issues related to joint data/pilot carrier frequency and phase tracking. Two different methods are proposed to overcome these issues: (i) an adaptive bandwidth joint data/pilot phase tracking loop, and (ii) a Kalman filter based joint data/pilot tracking. Both the adaptive bandwidth algorithm and the Kalman filter utilize carrier-to-noise density ratio (C/N0) estimates as a measure of thermal noise. Hence, it was necessary to have a reliable technique for estimating C/N0 and a comprehensive analysis of the C/N0 estimation process with emphasis on the use of both the data and pilot channels as input is provided. This analysis is utilized for the design of a novel iterative joint data/pilot C/N0 estimator, which is shown to be reliable (in terms of bias and noise variance) under weak signal environments. The C/N0 estimator has been integrated with the proposed tracking strategies that have been analyzed with respect to pilot-only tracking. The results indicate no significant performance loss in terms of tracking sensitivity when using joint data/pilot tracking. On the contrary, joint data/pilot tracking is more effective under weak signal and dynamic conditions. |
