MITIGATION OF CONTINUOUS INTERFERENCE IN RADIO ASTRONOMY USING SPATIAL FILTERING

The contamination of radio astronomical measurements by man-made Radio Frequency Interference (RFI) is becoming an increasingly serious problem and therefore the application of interference mitigation techniques is essential. Most current techniques address impulsive or intermittent interference and are based on time-frequency detection and blanking. Continually present interferers cannot be cut out in the time-frequency plane and have to be removed using spatial filtering. One technique is based on the estimation of the spatial signature vector of the interferer from short-term spatial covariance matrices followed by a subspace projection to remove that dimension from the covariance matrix, and by further averaging. The projections will also modify the astronomical data, and hence a correction has to be applied to the long-term average to compensate for this. In this paper we analyse the performance of this spatial filtering algorithm.