Statement of the Problem

Background:

Radio Frequency Interference (RFI) has become an increasing problem for microwave remote sensing in Earth Science applications. Data from the AMSR-E instrument shows widespread interference throughout much of the United States, particularly in heavily populated areas. [1] The ESTAR instrument shows significant spurious RFI from air traffic control radar in the L-band spectral window set aside for passive use. [2] These studies show that RFI is a major concern for microwave remote sensing of the earth. Two L-band radiometer instruments, Aquarius and Hydros, are currently being developed at the NASA/Goddard Space Flight Center. For both of these instruments, RFI is expected to be a potential source of error or data-loss, particularly in the soil-moisture data collected by Hydros.

The Design:

This design project is funded by the Global Precipitation Measurement (GPM) Mission at the NASA/Goddard Space Flight Center. The project design and implementation will be done at the University of Massachusetts Amherst in collaboration with GPM. The project has been allocated $12,000 by GPM.

With the growing speed of digital electronics, we can replace some analog components with digital signal processing to remove RFI before it is permanently married to the signal.

• The prototype will be delivered by May 2006
• Cost will not exceed $12,500
• The prototype will detect and remove narrow-band RFI with the input signal
• The prototype will do on-board averaging of the input power after the interference has been removed
• An analog front end will simulate a microwave radiometer and provide test signals to the prototype

Deliverables of the Design Project:

• One RFI-mitigating radiometer receiver prototype
• One analog test signal generator

Works Cited

1. Li, L., E.G. Njoku, E. Im, P.S. Chang, K. St. Germain, “A Preliminary Survey of Radio-Frequency Interference Over the U.S. in Aqua AMSR-E Data,” IEEE Trans. on Geoscience and Remote Sensing, vol.42(2), pp. 380-390, 2004.
2. Piepmeier, J.R., M. Midon, A. Caroglanian, O.C. Ugweje, “Radio frequency survey of the 21-cm wavelength (1.4 GHz) allocation for passive microwave observing,” Geoscience and Remote Sensing Symposium, vol. 3, pp. 1739-1741, July 2003.