Title of Presentation: Development of an Agile Digital Detector for RFI Detection and Mitigation on Spaceborne Radiometers

Primary (Corresponding) Author: Christopher S. Ruf

Organization of Primary Author: Space Physics Research Laboratory, University of Michigan

Co-Authors: Roger De Roo, Steve Gross, Steve Rogacki, Sidharth Misra and April Warnock

Abstract:  Passive microwave observations for Earth science are becoming increasingly contaminated by Radio Frequency Interference (RFI) from man made sources of emission such as telecommunication transmissions and civilian and military radars.  If the RFI has a very high power level, it can usually be identified and flagged.  If the RFI has a relatively low power level, it will often be mistaken for the variability in the observations that is expected of natural geophysical signals.  This can have a very significant detrimental effect on the value of archival data records, such as are used for climate studies, and on operational uses of the measurements, e.g. for use as observational constraints on numerical weather forecast. 

A new type of detector has been developed that can reliably identify and remove RFI from radiometer observations even when it has an extremely low power level.  The Agile Digital Detector (ADD) can discriminate between RFI and natural thermal emission signals by directly measuring higher order moments of the signal than the variance that is traditionally measured.  After detection, the ADD then uses high-resolution temporal and spectral filtering methods to selectively remove the RFI.  Several prototype versions of the ADD have been developed and integrated with various field deployable microwave radiometers.  A series of field campaigns has been conducted to evaluate their performance and to assess the costs and benefits associated with their design parameters.  Details of the ADD design and results of the field campaigns will be presented.  Issues related to the extension of the design to a spaceflight qualified version will also be examined.