Testing GPS L5 Acquisition and Tracking Algorithms Using a Hardware Simulator

The ever increasing demand for navigation and location services has fostered the need for higher performance Global Navigation Satellite Systems (GNSSs). The GPS L5 signal, part of the US effort to modernize GPS, was designed to respond to the above demand in terms of measurement accuracy, tracking robustness and tracking sensitivity. These improvements were achieved through the design of a more efficient signal structure. However, in order to fully exploit these improvements, new architectures have to be designed for the acquisition, tracking and data demodulation processes. This paper focuses on acquisition and tracking. First, a cascaded acquisition algorithm is proposed. The first step, referred to as coarse acquisition, is used to estimate the Doppler frequency and PRN code delay of all the visible satellites. The second step, referred to as fine acquisition, is then used to estimate the NH code delay and refine the Doppler frequency estimate. In order to do so, an intermediate tracking step, meant to remove the residual Doppler frequency prior to NH code alignment, is introduced. An innovative data/pilot combined tracking algorithm is then introduced. This algorithm coherently recombines the data and pilot correlators’ output prior to the implementation of a common discriminator and loop filter. This implementation enables optimal noise mitigation (as the noise samples are independent and combined prior to any non-linear operation) and alleviates the problem of half-cycle slips occurrence on the data channel.