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Digitally Steered Phased Antenna Array for GPS Applications

This array improves GPS navigation at high altitude and in the presence of interference. Goddard Space Flight Center, Greenbelt, Maryland GPS signals are sparse and weak at high altitudes above the GPS constellation; this includes GEO and HEO orbit regimes. Spacecraft operating here need a high-sensitivity receiver capable of acquiring and tracking these weak signals throughout their orbits. Most space GPS receivers are designed to operate in the LEO regime below the GPS constellation and will perform poorly at high altitude. The Goddard Space Flight Center (GSFC) Navigator GPS receiver is designed for above-the-constellation applications and can provide adequate performance for many missions. The innovation described here provides large sensitivity increase through improvement of the receiver’s antenna gain. The technology can be applied to a standard LEO GPS receiver to enable adequate high-altitude performance, or to a specialized high-altitude receiver, like the GSFC Navigator, to further improve its high-altitude performance. The innovation can also be used to mitigate interference, including multipath and RF jamming signals for operation in any regime.

Posted in: Briefs, TSP

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Broadband Circularly Polarized Antenna Array for Mars Rover Direct-to-Earth Communications

Printed circuit board technology is used, which requires almost no hand assembly. NASA’s Jet Propulsion Laboratory, Pasadena, California Mars rovers and other landers typically use UHF relay to return their science and engineering data to Earth. Direct-To-Earth (DTE) communications are typically used for commanding. If future UHF relay capability becomes diminished, Mars landers may be forced to use DTE communications to meet their data return requirements. An augmented DTE capability with a high-gain antenna and a higher-power transmitter are required to support the relatively high data volume returned in a typical mission. The research for this innovation has developed an antenna architecture that can support such an augmented DTE capability. This antenna architecture comprises an array of microstrip patch subarrays fed by a waveguide corporate feed network, producing a net gain of 30 dBic at the array input.

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Robust, Low-Density Parity- Check Decoder Design to Mitigate Pulsed Radio Frequency Interference

Lyndon B. Johnson Space Center, Houston, Texas Low-Density Parity-Check (LDPC) codes are a class of forward error correction (FEC) linear block codes that provide near-capacity performance for power-efficient communications. Optimum decoding requires accurate combining ratio estimation to scale the input signal in an additive white Gaussian noise channel (AWGN). Test data and analysis show that the performance of the optimal LDPC decoding algorithm is severely degraded when encountering pulsed radio frequency interference (RFI) from sources such as ground-based radars.

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Ensemble

Ensemble tools for different missions share a common look and feel, easing the transition of personnel between projects. NASA’s Jet Propulsion Laboratory, Pasadena, California Success in mission operations relies on achieving consensus amongst a wide variety of personnel with diverse backgrounds and education. Previously, NASA missions relied on disparate tools with a variety of inconsistent interfaces. These tools greatly influence how members of the mission communicate with each other, increasing confusion and reducing consensus. Ensemble provides a shared interface that helps scientists and engineers of differing disciplines to collaborate effectively. Within a single tool, Ensemble allows scientists and engineers to efficiently discuss objectives and understand the tradeoffs between exploration and discovery.

Posted in: Briefs, TSP, Electronics & Computers

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Mars Science Laboratory Frame Manager

NASA’s Jet Propulsion Laboratory, Pasadena, California One of the highly desired enhancements to the Mars Exploration Rover (MER) and Phoenix flight missions was the centralized coordinate transform database maintained onboard. Without the database, there are quite a few operations that require cumbersome, error-prone manual calculations on the ground such as pointing a mast camera to an arm tool and driving the rover to the goal defined in a previous site. The Mars Science Laboratory (MSL) Frame Manager flight software implements a centralized frame tree database, which eliminates these cumbersome, error-prone calculations of coordinate entries for commands.

Posted in: Briefs, Electronics & Computers

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SIVO-PyD: A Python Distribution for Scientific Computing Visualization

Goddard Space Flight Center, Greenbelt, Maryland SIVO-PyD gathers and automatically installs (in various computing platforms) a collection of Python-related packages for scientific computing and visualization. All of the packages in distribution are accessible within the Python framework. The distribution is self-contained and can be extended with minimal work.

Posted in: Briefs, TSP, Electronics & Computers

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iPhone App to Facilitate Airborne Radar Operations

NASA’s Jet Propulsion Laboratory, Pasadena, California The Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) is an Earth imaging radar that flies on a Gulf-Stream Jet. Its mission is to collect data for NASA scientists who are using Synthetic Aperture Radar to develop methods for monitoring changes in the Earth’s surface. As with many other technologies, there is always the possibility of technological or human errors. Since smartphones are mobile, common, and powerful devices, they can be used to reduce the possibility of operator error when the radar is being configured for flight.

Posted in: Briefs, Electronics & Computers

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