Seamless Handover of Satellite Tracking Using Geographic Aiding

In high-speed terrestrial vehicles, such as passenger or freight trains, moving through a cluttered environment means intermittent availability of navigation satellite signals. This paper presents a method for seamlessly handing over signal tracking from one satellite receiver to another, when both are mounted on the same train. For this purpose the paper looks at the tracking loop in a typical satellite navigation receiver and proposes ways of computing estimates of code phase and carrier frequency to initialize tracking. We test a proof-of concept implementation of the method in simulation. The tests demonstrate the technical feasibility of seamless handover of satellite tracking between navigation satellite receivers.