Efficient AOA Estimation Techniques for GPS Signal

Abstract

Global Positioning System (GPS) interference signals are suppressed using angle-of-arrival (AOA) techniques, while at the same time the power of the GPS signal is enhanced. After estimating all AOAs from the received signal, we must determine which AOA corresponds to the GPS signal of interest, and in the presence of high-power interference signals. In this paper, we describe an algorithm for selecting the GPS AOA by first comparing all AOAs derived from the received signals before despreading. Although this approach has excellent performance, it has a high computational complexity. In order to overcome this drawback, we introduce a modification that yields an efficient GPS AOA estimation algorithm, which is based on a modified despreader and the constant modulus (CM) array cost function. The CM array is capable of selecting signals that have a constant modulus while rejecting non-CM interference signals. The modified despreader is the mechanism that allows this to be achieved, where unlike the interference signals, the GPS signal of interest maintains a constant modulus.