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NRAO/Socorro Colloquium Series

Brian Jeffs

BYU

Progress in Adaptive Spatial Filtering for RFI Mitigation in Radio Astronomy


Spatially adaptive filtering (beamforming) involves linearly combining signals from an array of sensors to achieve a desired directionally selective response pattern. This can be used to reject interfering signals if they have an identifiable spatial signature. The filter solution must be adaptive, with regular estimation updates over time to account for unknown and/or changing spatial statistics of the undesirable sources. Many radio astronomical instruments, including conventional synthesis imaging arrays of dish antennas, low frequency aperture arrays, and new phased array feeds for single dish and synthesis array radio astronomy, are all suitable platforms for spatial filtering algorithms. For years the literature has discussed the promise of such techniques to open up spectral bands which have previously been off limits due to strong man-made interference. Unfortunately, very little of this work has yet migrated into regular use on real-world instruments.

We will discuss reasons for this slow adoption, ranging from high computational burden, to poor cancelation performance in the typical radio astronomical signal scenario, to lack of a critical science case that cannot be addressed by simply avoiding the interference. Differences between the classical wireless communications and radar adaptive filtering applications, and radio astronomy will be addressed. Recent advances in beamforming algorithms which could make spatial adaptive filtering more attractive to the astronomical community will be presented, and some possible next steps to encourage adoption will be considered. We will also show that our recent work in phased array feeds provides and excellent platform for spatial RFI mitigation.



March 8, 2013
11:00 am

Array Operations Center Auditorium

All NRAO employees are invited to attend via video, available in Charlottesville Auditorium, Green Bank Room 137 and Tucson N525.

Local Host: Urvashi  Rao

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