A special-purpose software Global Positioning System (GPS) receiver designed for remote sensing with reflected GPS signals is described in "Delay/Doppler-Mapping GPS-Reflection Remote-Sensing System" (NPO-30385), which appears on the previous page. The input accepted by this program comprises raw (open-loop) digitized GPS signals sampled at a rate of about 20 MHz. The program processes the data samples to perform the following functions: detection of signals; tracking of phases and delays; mapping of delay, Doppler, and delay/Doppler waveforms; dual-frequency processing; coherent integrations as short as 125 μs; decoding of navigation messages; and precise time tagging of observable quantities. The software can perform these functions on all detectable satellite signals without dead time. Open-loop data collected over water, land, or ice and processed by this software can be further processed to extract geophysical information. Possible examples include mean sea height, wind speed and direction, and significant wave height (for observations over the ocean); bistatic-radar terrain images and measures of soil moisture and biomass (for observations over land); and estimates of ice age, thickness, and surface density (for observations over ice).
This program was written by Stephen Lowe of Caltech for NASA's Jet Propulsion Laboratory.
This software is available for commercial licensing. Please contact Don Hart of the California Institute of Technology at (818) 393- 3425. Refer to NPO-30386.
This Brief includes a Technical Support Package (TSP).
Software for a GPS-Reflection Remote-Sensing System
(reference NPO-30386) is currently available for download from the TSP library.
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Overview
The document is a NASA Technical Support Package detailing advancements in sensor systems and software for remote sensing applications. It primarily focuses on two innovative technologies: real-time microbial detection in water and a GPS-reflection remote-sensing system.
The first section discusses the development of sensor systems capable of real-time detection and quantification of microbes in water without the need for sampling. These systems utilize arrays of optical sensors, miniature electronic data-acquisition circuits, and optoelectronic interfaces. They are designed for long-term, in-line monitoring of waterborne microorganisms, particularly in water-reclamation systems aboard future spacecraft. The sensors can distinguish among classes of microbes, although they do not identify individual species. This technology is crucial for ensuring water quality in space missions, where maintaining a safe and clean water supply is essential for crew health and mission success.
The second section introduces a software program developed for a GPS-reflection remote-sensing system. This software processes open-loop, 20 MHz data to perform various functions, including GPS signal detection, phase and delay tracking, and dual-frequency processing. It can extract precise observable time tagging and decode navigation messages. The system is capable of processing signals from all detectable satellites without dead time, allowing for real-time data collection. The software can be used to derive important environmental metrics, such as mean sea height, wind speed, soil moisture, and ice thickness, by analyzing the time difference between direct and reflected GPS signals.
The document emphasizes the novelty of these technologies, highlighting their potential to improve environmental monitoring and resource management both in space and on Earth. The GPS-reflection system, in particular, offers a versatile tool for mapping and analyzing various terrestrial and oceanic features, contributing to our understanding of environmental changes.
Overall, this NASA Technical Support Package showcases significant advancements in sensor technology and remote sensing software, reflecting ongoing efforts to enhance monitoring capabilities in challenging environments, such as space and remote areas on Earth. These innovations not only support space exploration but also have practical applications for environmental science and resource management.
