The majority of 3G mobile phones have an integrated GPS chip enabling them to calculate a navigation solution. But to deliver continuous and accurate location information, the satellite tracking process has to be stable and reliable. This is still challenging, for example, in heavy multipath and non-line of sight (NLOS) environments. New families of Galileo and GPS navigation signals, such as Alternate Binary Offset Carrier (AltBOC), Composite Binary Offset Carrier (CBOC), and Time-Multiplex Binary Offset Carrier (TMBOC), will bring potential improvements in the pseudorange calculation, including more signal power, better multipath mitigation capabilities, and overall more robust navigation. However, GNSS signal tracking strategies have to be more advanced in order to profit from the enhanced properties of the new signals.In this paper, a tracking algorithm designed for Galileo E1 CBOC signal that consists of two steps, coarse and fine, with different tracking parameters in each step, is presented and analyzed with respect to tracking accuracy, sensitivity and robustness. The aim of this paper is therefore to provide a full theoretical analysis of the proposed two-step tracking algorithm for Galileo E1 CBOC signals, as well as to confirm the results through simulations as well as using real Galileo satellite data. 1. Introduction New GPS and Galileo signals use new modulations, such as AltBOC, CBOC, and TMBOC that have the potential to improve navigation through advanced signal properties, such as more signal power, better multipath mitigation capabilities, and overall improved signal cross-correlation properties. Certainly, a major innovation brought by the new modulation schemes consists of the presence of two distinct components, namely, the data and pilot channels that carry two different pieces of information. The data channel contains the navigation message, whereas the pilot channel is dataless, allowing long coherent signal integration that, in turn, allows more precise determination of the ranging information. For carrier tracking, the presence of a pilot channel enables the combined use of pure PLL (Phase Lock Loop) discriminators and longer coherent integration time. Code tracking can be organized as data/pilot collaborative tracking [1, 2], where two channels (data and pilot) are used in the estimation of the code error, decreasing the thermal noise error and improving overall tracking. Several tracking algorithms proposed for Galileo E1 CBOC signals were derived from tracking schemes developed for BPSK (Binary Shift Keying) and B O C ( 1 ,
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