Dual polarization gain estimation for radio telescope arrays

The complex receiver gains and sensor noise powers of radio telescope arrays are initially unknown and need to be calibrated. This can be accomplished by observing a relatively strong astronomical point source. Here we consider calibration algorithms for the case of dual polarized arrays and formulate new least squares algorithms based on factor analysis, parallel factor analysis, and eigenvalue decompositions. We show that at least three sources with different polarization states are needed to obtain a unique solution for the gains. We also propose a closed form solution which has a performance comparable to the iterative parallel factor method.