Spatial filtering using a multi-beam receiver

Spatial filtering has traditionally been the province of antenna arrays, where both the Radio Frequency Interference (RFI) and celestial signals appear at all receivers. In the implementation described here, spatial filtering techniques are applied to data taken with the 20 cm multibeam receiver on the Parkes 64 m dish. Here, each of the feeds has independent celestial signal and system noise, but common RFI. The signal processing requirements of the technique are outside the capacity of the standard spectrometer for the multibeam receiver at the observatory. As a result, a customised baseband recoding system was used to record the raw voltage data to disk, which were then processed offline in software. The results demonstrate that spatial filtering methods provide powerful tools for interference mitigation with an array feed receiver.