Polar excision for radio frequency interference mitigation in radio astronomy

As radio interference becomes pervasive, new methods might help to preserve reception of weak radio astronomical sources. When there is powerful interference that overlaps the desired weak signal in the frequency and time domains, spatial mitigation offers a potential solution. However, when the powerful interference and desired weak signal also exhibit similar — possibly identical — spatial signatures, existing interference mitigation methods deliver poor recovered signal-to-noise ratio. This paper explains a nonlinear technique that can outperform the orthogonal and oblique projection processors when the angle between the interference and desired signal spatial signatures is less than 45 degrees. Analytical and Monte Carlo simulation results demonstrate the performance benefits and limitations.