Performance Analysis of DBF Algorithm in GPS Software Receiver

摘要

In the paper,the performance analysis of DBF algorithms associated with different prior information is performed to evaluate how the measurements are influenced by different DBF algorithms.Firstly,we introduce the multi- antennas GPS signal source and GPS software receiver with adaptive array processing.Then,the measurement bias and its prediction are analyzed in detail.And we come to a conclusion that the FIR filtering with a linear phase response does not exhibit any carrier phase error, but produces a constant code phase error determined by the group delay,which can be used as the measurement correction.Furthermore,an approach is developed to eliminate the distortion effect induced from space time adaptive processing(STAP)through specific constraints on STAP and accurate predictions of measurement biases. Compared with the traditional method with L constraints on STAP and L denoting the number of delay tap lines, the approach needs only half symmetry constraints to ensure the linear phase response in the direction of the desired GPS signal,which can eliminate the measurement biases.In addition,the developed approach consumes less degrees of freedom to constrain weight coefficients and thus may improve carrier to noise density ratio(CN_0), especially in the occasion with many jammers.Besides, the traditional STAP approach with multiple constraints of one on STAP is modified by exposing a set of well pre- designed coefficients of low-pass FIR filtering with linear phase and appropriate passband bandwidth to avoid the attenuation of GPS signal when L is large.Finally, simulation results validate the theoretical analysis of the code phase and carrier phase measurements,and demonstrate the performance of approaches with different constraints,including CN_0,the code phase and carrier phase.