Gain decomposition methods for radio telescope arrays

In radio telescope arrays, the complex receiver gains and sensor noise powers are initially unknown and have to be calibrated. Gain calibration enhances the quality of astronomical sky images and moreover, improves the effectiveness of certain radio telescope phased-array data processing techniques, such as radio interference (RFI) mitigation and beamforming. We present several closed form and iterative complex gain estimation methods. These methods are analyzed and compared to the Cramer-Rao lower bound for the variance of the estimated gain. The models are tested both on simulated data and on observed telescope data.