Share Email Print

Proceedings Paper

Analysis of reflected Global Positioning System (GPS) signals from land for soil moisture determination and topography mapping
Author(s): Omar Torres; Stephen J. Katzberg
Format Member Price Non-Member Price
PDF $17.00 $21.00

Paper Abstract

GPS signals reflected from the ocean surface have been used in remote sensing applications to determine sea-state and wind speed. Studies show that, with rougher surfaces, GPS signal pulses scatter more, which creates weaker and wider pulses at the receiver. Based on this model, the correlation between soil moisture, topography, and GPS signals was studied using reflections off the ground. The data used for the study were gathered during two flights in 1998 and 2001 around Austin, Texas and Albuquerque, New Mexico and later processed at Langley Research Center. The power of the signals were analyzed and plotted over Digital Elevation Models (DEMs) and Landsat7 images (near- and mid-infrared bands) to interpret the correlation of signal behavior with topography. In addition, the received signal's conduct was correlated with soil moisture data obtained from the Department of Agriculture's Soil Climate Analysis Network (SCAN) sites at Prairie View (Texas) and Adams Ranch (New Mexico). The strengths of the reflected signals were observed larger near known bodies of water and farmlands where soil moisture levels are known to be high. In general, for flat lands, the power of the signals and soil moisture contents appeared to have a close-to-linear relationship. In addition, the received pulses widened when reflected over rapid-changing topography in Texas, but any relationship among these was not perceived in New Mexico. Further studies are needed to obtain a definite relationship among soil moisture and reflected signal strength and to introduce satellite position in the signal-topography study.

Paper Details

Date Published: 24 September 2002
PDF: 7 pages
Proc. SPIE 4814, Earth Observing Systems VII, (24 September 2002); doi: 10.1117/12.451371
Show Author Affiliations
Omar Torres, Univ. of Texas/El Paso and NASA Langley Research Ctr. (United States)
Stephen J. Katzberg, NASA Langley Research Ctr. (United States)

Published in SPIE Proceedings Vol. 4814:
Earth Observing Systems VII
William L. Barnes, Editor(s)

© SPIE. Terms of Use
Back to Top