Characterization and Mitigation of RFI Signals in Radar Depth Sounder Data of Greenland Ice Sheet

Abstract

Accurate measurements of fast flowing outlet glaciers in Greenland and Antarctica are of vital importance to improve ice-sheet models that predict the ice-sheets' contribution to sea-level rise over the next century. Radars with high sensitivity and advanced processing capabilities are required to sound ice in fast-flowing glaciers. We developed the multichannel coherent radar depth sounder/imager (MCoRDS/I) for ice thickness measurements and 3-D imaging of bedrock over important areas of Greenland and Antarctica. Radio frequency interference (RFI) degrades the sensitivity of the MCoRDS/I system, thus affecting the quality of the data collected. Data from the 2010 Greenland field season exhibited a degraded signal-to-noise ratio (SNR), requiring extensive RFI analysis, investigation, and mitigation for the MCoRDS/I system. Measurements were taken in an electromagnetic interference (EMI) chamber on individual sections of the MCoRDS/I system to isolate the sources of RFI. Then, RFI mitigation techniques were implemented for the offending sections and EMI chamber measurements verified the integrity of the solution prior to the 2011 Greenland deployment. Recorded data from the 2011 Greenland field season also verified that the RFI mitigation resulted in more than 20 dB improvement in the SNR compared to the 2010 Greenland data. The reduction of EMI emissions has also been beneficial to data collection in subsequent deployments.