Remote sensing stream flow and soil moisture by using reflected GPS Signals L1 & L2 observation and Doppler shifts with an Integrated GPS Receiver
ABSTRACT In this paper, a new application and development of a highly integrated GPS receiver with reflected GPS signals for stream flow and soil moisture will be described. First, both right hand circular polarization (RHCP) and left hand circular polarization (LHCP) antennas are employed so that direct and reflected signals can be acquired simultaneously. The direction of arrival of the signals may be along the reflected signal path or even along the line-of-sight of a particular satellite. An integer ambiguity algorithm has also been implemented. The precise point positions for RHCP and LHCP antennas are enhanced and processed by repeating instantaneous ionosphere delay correct model with deriving from LI and L2 carrier phase and troposphere estimated parameter model. During the development and test stage, the digital terrain elevation data (DTED) and visual elements of the satellite's images has been used and mapped with the integrated software. For remote sensing of river, ocean, and landscape, the accuracies of each reflected altitude are among 10 cm and 30 cm. The accuracies of each reflected area are converged among 2 cm and 10 cm. Unlike most existing GPS reflection experiment, The goal of the study is to exploit the carrier phase, Doppler shift, reflectivity of L1/L2 S/N0 signal-to-noise density ratio components of the reflected signals and direct signals for stream flow, disturbed water, dry soil, and wet soil object detection. The soil moisture should be classified by volumetric content of saturated water for soil and L1/L2 reflectivity on the GPS reflected footprint. The three dimensional stream flow modeling is predicted by using Doppler shifts due to surface reflection as a moving surface on the river. Each instantaneous moving surface should be exploited by each reflected GPS carrier phase and reflected point.