Title of Presentation: Analog Radio-Frequency Interference (RFI) Suppression System for Microwave Radiometers

Primary (Corresponding) Author: Priscilla N. Mohammed

Organization of Primary Author: NASA Goddard Space Flight Center

Co-Authors: Joseph K. Knuble, Jeffrey R. Piepmeier


Abstract:  Microwave radiometers use radio spectrum dedicated to sensing the environment. As wireless communications and other active services proliferate, this allocated spectrum is nearly being crowded out. The potential result is corrupted satellite measurements of the weather, the climate, and the environment. The Analog Radio-Frequency Interference Suppression System (ARFISS) is a combination of detection hardware and algorithms designed to address this problem. By observing the statistics of an incoming signal to a microwave radiometer, it can be determined if the signal is contaminated by radio frequency interference (RFI) which can cause unwanted anomalies in the data.  The analog multiplier system is part of ARFISS which can potentially be used to detect and mitigate radio frequency interference (RFI) in conventional radiometers.  In addition to measuring statistics of an incoming signal, changes in the video spectrum of the square-law detector can be monitored to detect RFI.  This paper will present experimental results to show proof of concept as well as results of the post-detector spectral analysis.  This design, which uses purely analog components at radio and/or intermediate frequencies, allows the system to easily augment conventional radiometer architectures used in both airborne and space borne instruments. An equivalent high- speed digital design would add an impractical level of cost and complexity to radiometer designs using today's technology. Thus, the Analog Radio-Frequency Interference Suppression System (ARFISS) is being developed to reduce risk and to enable NASA and the Nation to maintain the impressive legacy of precision Earth observations made using microwave radiometers into the future whilst the radio spectrum becomes evermore utilized.