Search NASA⌕ Search

SEARCH · Search NASA

Results for “Positioning System”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

A navigation algorithm for single channel low-cost GPS receiver

A sequential navigation algorithm for a navigator using the Global Positioning System satellites is developed and tested for both noise-free and noisy system models. Data from a six-hour flight from California to Hawaii (C5A aircraft) simulates a true user to test the accuracy of the user's position for a sequential navigation system. For error reduction in the user's position in the sequential navigation system (considering 100 m as a maximum average error tolerated by any low-cost GPS user) an analysis of error sources in the sequential system has led to the use of range-ephemeris rate to translate ranges to a common point in time and to use velocity aiding at the time of a satellite disappearance. To reduce the user's position and velocity errors in a noisy navigation system an 'alpha-beta' two-pole filter is implemented whose optimum alpha is obtained experimentally. A user's position error of 73 m at noise range error of 30.48 (1sigma) is achieved.

Parsiani, H.↗
NASA NTRS2016

Use and Protection of GPS Sidelobe Signals for Enhanced Navigation Performance in High Earth Orbit

The application of the Global Positioning System (GPS) for navigation of spacecraft in High and Geosynchronous Earth Orbit (HEO/GEO) has crossed a threshold and is now being employed in operational missions. Utilizing advanced GPS receivers optimized for these missions, space users have made extensive use of the sidelobe transmissions from the GPS satellites to realize navigation performance that far exceeds that predicted by pre-launch simulations. Unfortunately, the official specification for the GPS Space Service Volume (SSV), developed in 2006, assumes that only signals emanating from the main beam of the GPS transmit antenna are useful for navigation, which greatly under-estimates the number of signals available for navigation purposes. As a result, future high-altitude space users may be vulnerable to any GPS design changes that suppress the sidelobe transmissions, beginning with Block III space vehicles (SVs) 11-32. This paper presents proposed changes to the GPS system SSV requirements, as informed by data from recent experiments in the SSV and new mission applications that are enabled by GPS navigation in HEO/GEO regimes. The NASA/NOAA GOES-R series satellites are highlighted as an example of a mission that relies on this currently-unspecified GPS system performance to meet mission requirements.

Navigation↗
NASA NTRS1991

Terrestrial reference systems related to the TOPEX/Poseidon project

In the TOPEX/POSEIDON project, several satellite positioning systems, such as Laser, Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS), and Global Positioning Satellite (GPS) (on an experimental basis), will be used to track the satellite and to provide accurate orbits. Unfortunately, these systems will provide their dedicated tracking-station coordinates and the satellite orbits in different reference frames. Each technique will use, de facto, a different reference frame. In fact, even for the same technique, each group, depending on the hypothesis used in its computation, will use a different reference frame. This problem is not new for geodesists and can be overcome, in large part, but could create trouble for other scientists when they compare or combine different coordinate data sets. The main purpose of this investigation is to determine a consistent terrestrial system for TOPEX/POSEIDON in which all the tracking-station coordinates, all the orbit ephemerides, and all the other station coordinates of specific interest (such as tide gauges) could be expressed. Another issue of this investigation is the provision of reliable information concerning the relationships between all the possible reference frames of interest for th TOPEX/POSEIDON project. To be more explicit, we plan to provide the possible transformation formula between the TOPEX/POSEIDON terrestrial reference frame and the Laser, DORIS, GPS, and other internationally recognized frames such as the International Terrestrial Reference Frame (ITRF).

Boucher, Claude↗
NASA NTRS1995

Rapid, Precise, and Economical Analysis of Data from the Southern California Integrated GPS Network

The number of permanently operating precision Global Positioning System (GPS) receivers in the Southern California Integrated GPS Network has increased dramatically in the past year to several dozen. This number is expected to increase to hundreds within a few years. A prototype system to process all of these data, accurately, rapidly, and economically, has been in operation since May 1995.

Geophysics Global Positioning System GPS SCIGN↗
NASA NTRS1999

GPS and Ionosphere

The Global Positioning System (GPS) constellation of satellites is revolutionizing the science and technology of the Earth's ionosphere.

Global Positioning System (GPS) ionosphere total e↗
NASA NTRS1987

Space Station communications and tracking system

A comprehensive description of the existing Space Station communications and tracking system requirements, architecture, and design concepts is provided. Areas which will require innovative solutions to provide cost-effective flight systems are emphasized. Among these are the space-to-space links, the differential global positioning system for determining relative position with free-flying vehicles, multitarget radar, packet/isochronous signal processing, and laser docking systems. In addition, the importance of advanced development, tests, and analyses is summarized.

Dietz, Reinhold H.↗
NASA NTRS2016

Use and Protection of GPS Sidelobe Signals for Enhanced Navigation Performance in High Earth Orbit

GPS (Global Positioning System) Space Service Volume (SSV) signal environment is from 3,000-36,000 kilometers altitude. Current SSV specifications only capture performance provided by signals transmitted within 23.5(L1) or 26(L2-L5) off-nadir angle. Recent on-orbit data lessons learned show significant PNT (Positioning, Navigation and Timing) performance improvements when the full aggregate signal is used. Numerous military civil operational missions in High Geosynchronous Earth Orbit (HEOGEO) utilize the full signal to enhance vehicle PNT performance

Navigation Satellites↗
NASA NTRS2008

Position, Navigation, and Timing: GPS Scientific Applications

This slide presentation reviews the development and deployment of the Global Positioning System (GPS). This presentation also includes measuring space and time, GPS as a tool for science, development of high precision JPL GPS receivers, and technology and applications developments.

geodesy↗
DOE OSTI2025

Precision Time Protocol Performance Testing Over Optical Transport Network

The US Department of Energy Office of Electricity has partnered with Oak Ridge National Laboratory (ORNL) to find alternative precision timing solutions for the nation’s power grid. This effort is in response to the vulnerabilities identified in the Global Navigation Satellite System (GNSS), of which the US Global Positioning System (GPS) platform is a part. Additionally, Executive Order 139055 has highlighted the need for alternative or backup timing solutions. ORNL has established a Timing Lab and has been testing various technologies and timing devices as part of this effort. Precision Time Protocol (PTP), and the off-the-shelf timing devices and network connections that support it, are among the alternatives being tested. This work reports the accuracy of PTP over an Optical Transport Network (OTN) and is part of a series published by the Center for Alternative Synchronization and Timing (CAST).

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS1980

Onboard navigation - The near-earth options

This paper summarizes anticipated onboard navigation accuracies and user system characteristics for near-earth spacecraft. Alternate onboard systems configurations using inputs from the Tracking and Data Relay Satellite System (TDRSS) and the DOD NAVSTAR Global Positioning System (GPS) are described. Initial simulation results indicate that TDRSS will provide accuracies of 100 meters or less, and GPS can permit user spacecraft orbit determination to within 10 meters. Specific GPS user equipment developments for Landsat-D and Shuttle are outlined, along with future low-cost versions of these systems.

Kurzhals, P. S.↗
NASA NTRS1982

Spacecraft induced error sources

The attitude control and measurement systems aboard the LANDSAT 2 and D satellites are described and associated errors are discussed. Also, the ephemeris errors from various tracking systems are examined. Use of the Global Positioning System and improved attitude control instruments is expected to greatly reduce the errors in LANDSAT D in comparison with previous LANDSATS.

Heuberger, H. S.↗
NASA NTRS1989

Applying kinematic GPS to airborne laser remote sensing

Results from the application of differential carrier phase tracking of the Global Positioning System (GPS) constellation of satellites to precise positioning (sub-10 cm) of an aircraft are presented. These aircraft positions are utilized in the process of providing geodetic quality position information for airborne laser 'footprint' locations on the surface of the earth. The combination of these techniques provides a rapid, cost effective means for collecting geodetic and topographic data, including sea surface topography. Operational techniques and constraints, along with results from recently collected data, are presented.

Krabill, William B.↗
NASA NTRS1993

GPS system simulation methodology

The following topics are presented: background; Global Positioning System (GPS) methodology overview; the graphical user interface (GUI); current models; application to space nuclear power/propulsion; and interfacing requirements. The discussion is presented in vugraph form.

Ewing, Thomas F.↗