Multichannel detection and spatial signature estimation with uncalibrated receivers

A problem occuring in radio astronomy is the detection and cancellation of spatially correlated interfering signals entering via the sidelobes of the telescopes in an array. A complicating factor is that the noise powers can be different at each telescope. For the case that the sensors are uncalibrated, we formulate the detection problem as a test on the covariance structure, state the GLRT for this problem, and relate it to a simpler ad-hoc detector. We derive algorithms to estimate the noise powers and the subspace of interferer signature vectors. Once the subspace is estimated, the interference can be projected out. We compare this method to the conventional multichannel subspace detector and show its robustness to non-identical channels on data collected with the Westerbork radio telescope.