High sensitivity GPS receiver

摘要

A high sensitivity GPS receiver includes an acquisition engine and a tracking engine. The acquisition engine processes GPS satellite data at data rate that is substantially equal to twice the coarse acquisition (CA) code chip rate. This data rate advantageously enables the acquisition engine to process GPS satellite data with relatively less hardware area than traditional GPS acquisition approaches. In one embodiment, the high efficiency acquisition engine may be over-clocked, thereby allowing different phases of a CA code to be correlated quickly. The tracking engine can advantageously process GPS satellite data at a data rate that does not have an integer relationship to the CA code chip rate.

主权项

1. A method of tracking a Global Positioning Satellite (GPS) signal, the method comprising:
executing a pull-in stage by setting a center frequency of a phase-locked loop (PLL) having an initial bandwidth to a Doppler frequency of the GPS signal; determining whether the PLL has converged in a first occurrence over an initial integration time; determining whether the PLL has false convergence by comparing a power of an in-phase component to a power of a quadrature component of the GPS signal if the PLL has converged in the first occurrence; executing a transition stage by decreasing the initial bandwidth and increasing the initial integration time if the PLL does not have false convergence; determining whether the PLL has converged in a second occurrence after execution of the transition stage; and executing a tracking stage by fixing a decreased bandwidth for the PLL and an increased integration time if the PLL has converged in the second occurrence.