A Maximum-likelihood based mutual coupling calibration algorithm in the presence of multipath for GPS antenna array

Abstract

In GPS area, several GPS antenna array calibration techniques have been proposed to calibrate errors like gain/phase error in each channel, mutual coupling effect between antennas and array orientation error in array. However, none of these techniques consider possible multipath effect of calibrating sources, which can cause inaccurate estimations of array errors. In this paper, an algorithm based GPS antenna array technique is proposed to calibrate array orientation error and modeled mutual coupling effect in the presence of multipath signals. The calibration algorithm uses the fact that if the errors in the array are correctly calibrated, the array manifold and the signal should span the same subspace at the signal bearings to estimate the modeled errors. The array errors and DOAs of multipath signals are estimated by maximum-likelihood based approaches in an iterative sequence. This paper first describes the models of the received signals and the errors. The four steps iterative calibration algorithm is described later. At last, the performance of the algorithm is analyzed by the simulations and the experiment.