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.
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ABSTRACT: The remote sensing techniques have put great pressure on real-time waveform post-processing design. Due to the intensive computation and multi-channel waveform integration, the overhead between the processing time and the storage of amount of data prior to downlink issues has lead us to get the solution of task-level parallelism. With the development of IC design and innovation of architecture, embedded system can range from a single microprocessor to a complex multi-processor and even including the embedded operating system (OS) on a chip. Therefore symmetric multiprocessing (SMP) with embedded OS offers an attractive way to expose coarse-grained parallelism application. In this paper we demonstrate a new modeling approach. In order to simplify the system; a workload model is derived from a remote sensing application, which represents the workload characteristic and time degrading factors. The intention is to leverage the task-level parallelism load is evenly to each processor in SMP, with the OS level testing to speculate the bottleneck in hardware level. This parallel workload model which maps to a 6-LEON3 SMP architecture, attains a 2.7x mean speedup over a single-LEON3 baseline; with 3-LEON3 attains a 2.23x mean speedup; with 2- LEON3 attains a 1.78x mean speedup over a single-LEON3 baseline. Due to the involved sharing resources and scheduling of multiple CPUs, the system will have a degrading in processing speed. With this lag we could infer the hardware pipeline efficiency. And afford on the processor-set subsystem and memory subsystem analysis reveal the affects on the system throughput.Proceedings of SPIE - The International Society for Optical Engineering 05/2009; DOI:10.1117/12.821549 · 0.20 Impact Factor
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ABSTRACT: A new application using reflected Global Positioning System (GPS) signals collected by a tightly integrated GPS receiver for ground object detection and soil moisture estimation is developed. Several operational considerations are discussed to successfully acquire and track the weakly reflected GPS signals from the ground surface. Both right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) antennas are employed so that the direct and reflected signals can be received simultaneously. The arrival direction of the signal may be along the reflected signal path or the line-of-sight of a particular satellite. Unlike most existing GPS reflection experiments, the goal of this paper is to exploit the carrier phase observables for soil moisture estimation and ground object detection. During the development and test stages, ground truth measurements are also performed for different soil water content over different surface roughness. The ground truth measurements are expected to be useful for the moisture content in a small sample to check with the moisture variations in the lots instead of using bulk samples. The roughness effect parameter is calibrated by accounting for the standard deviation of height on soil surface and reflective footprint from GPS RHCP/LHCP accurate positioning data.IEEE Transactions on Instrumentation and Measurement 04/2009; DOI:10.1109/TIM.2008.2005821 · 1.71 Impact Factor
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ABSTRACT: This paper describes the development and application of a highly integrated Global Positioning System (GPS) receiver that employs reflected GPS signals to measure the floodwater levels, sea levels, and soil moisture of riverbeds. Both right- and left-hand circular polarization antennas are employed to simultaneously obtain direct and reflected signals. The objective of this paper is to use the carrier-phase Doppler shifts reflectivity of L1 and L2 band reflected signals and direct signals to determine the floodwater and sea levels in riverbeds, as well as to distinguish wet soil from bare soil. In monitoring coastal tidal currents, water levels, and floodwater levels, the reflection heights of this system are accurate to within 29 ~ 31 cm. Furthermore, the currents at reflection points are estimated using differential carrier Doppler shifts and a coordinate rotation correction model, which provide velocity vectors for flows speed of approximately 5 ~ 265 cm/s.IEEE Transactions on Instrumentation and Measurement 02/2010; 59(1-59):153 - 163. DOI:10.1109/TIM.2009.2022113 · 1.71 Impact Factor