Assessing Three New GPS Combined L1/L2C Acquisition Methods

Abstract

This paper presents three new global positioning system acquisition methods that make use of both L1 C/A and L2C signals in a combined way. The methods perform joint estimation of the Doppler frequencies and code delays on L1 and L2 without increasing the coherent integration time. Each method is assessed in terms of theoretical probabilities of false alarm and detection as well as through testing with real intermediate frequency data. The first method is a noncoherent summation of L1 and L2 correlator outputs. The second method implements an independent differential summation of L1/L2 correlator outputs, and the third method uses a noncoherent plus dependent differential summation. While each method provides increased detection performance compared with the standard noncoherent acquisition applied on L1 C/A, the noncoherent plus dependent differential summation method outperforms all of the others in the scenarios investigated.