... 577 CALIBRATING GPS WITH TWSTFT FOR ACCURATE TIME TRANSFER ... 83% of UTC time links are obtained via GPS observations. ...
DTIC Science & Technology
The Accurate Time-Linked data Acquisition System (ATLAS II) is a small, lightweight, time-synchronized, robust data acquisition system that is capable of acquiring simultaneous long-term time-series data from both a wind turbine rotor and ground-based instrumentation. This document is a user's manual for the ATLAS II hardware and software. It ...
Energy Citations Database
The network of time links for the computation of TAI has always be chosen such as to allow a unique solution, i.e. not using any redundancy. In the present situation, many links can be computed with two or more techniques 'mostly TW and GPS' and the TW ne...
National Technical Information Service (NTIS)
International Association of Geodesy (IAG) to provide GPS data and highly accurate ... The GPS data flows from a global network of permanent GPS tracking ...
NASA Website
... In Section 3, we estimate the short-term stability of these techniques from direct measurements and, in Section 4, we infer the longer-term stability ...
This resource, published by a commercial producer of GPS equipment, introduces students to the concept of Global Positioning Systems (GPS). Topics include how GPS works and how accurate it is. There is also a brief description of the satellite network that makes the system work, and some sources of error in the ...
NSDL National Science Digital Library
... The use of GPS broadcast signals to determine azimuth was part of these studies. These studies showed that azimuths could be accurately ...
The conclusion from this is that Simone's base station as used to process the GPS data are accurate to +/- 0.3 metres. The field work by the Rover GPS unit ...
Feb 14, 2011 ... A GPS navigation system built for high Earth orbits. Until now, Global Positioning System (GPS) receivers, while providing an accurate and ...
... Satellite navigation using GPS has become a hot new area of GPS ... is well suited to providing accurate coverage for low earth orbiting satellites ...
... To compare the TWSTT result UTC(CRL)-UTC(CSA0) [by Dr. Hirotaka Yukawa, CRL] with the GPS result UTC(CRL)-UTC(CSA0) [by CSAO], we ...
The versatile GPS Pathfinder� Pro XRS receiver is the thoroughbred of GPS receivers. Offering a full range of accurate real-time correction sources, great performance in all GPS conditions backpack system Choice of field computer and field software DATASHEET HIGH-PERFORMANCE GPS WITH A WORLD
E-print Network
May 1, 2000 ... GPS is a dual-use, satellite-based system that provides accurate location and timing data to users worldwide. My March 1996 Presidential ...
National Geospatial-Intelligence Agency National Geospatial-Intelligence Agency THE NGA GPS MISSION Our Mission: To provide Timely, Accurate, and Leading Edge GPS-Based Products,...
Science.gov Websites
Global Positioning System (GPS) as well as highly accurate ephemerides. In the future these products are considered fundamental for the proper use of GPS in ...
Description: Global Positioning System (GPS) telemetry enables biologists to obtain accurate and systematic locations of animals. Vegetation can block signals ...
Treesearch
Northeast Brazil is one of its components. It is well known that knowing accurately the GPS position,. one may calculate the delay in the signal from the ...
on a seasonal model and do not accurately re ect daily to weekly variation. ... in the vicinity of the GPS antenna [4], is known to a ect all GPS sites at ...
Page 1. A GPS DISCIPLINED RUBIDIUM CLOCK ... ill' f h. Rubidium oscillator while maintaining an accurate fretl~ic~nr-y. Thc first algorithm. ...
In support of the DOE Low Wind Speed Turbine (LWST) program two of the three Micon 65/13M wind turbines at the USDA Agricultural Research Service (ARS) center in Bushland, Texas will be used to test two sets of experimental blades, the CX-100 and TX-100. The blade aerodynamic and structural characterization, meteorological inflow and wind turbine structural response will be monitored with an array ...
In support of a Work-For-Other (WFO) agreement between the Wind Energy Technology Department at Sandia National Laboratories and 3TEX, one of the three Micon 65/13M wind turbines at the USDA Agriculture Research Service (ARS) center in Bushland, Texas, has been used to test a set of 9 meter wind turbine blades, manufactured by TPI composites using the 3TEX carbon material for the spar cap. Data ...
DOE Information Bridge
We quantify and analyze the time differences between simultaneous results for several pairs of TAI laboratories using the Two-Way satellite Time Transfer (TWTT) and different techniques using geodetic GPS methods. These include the combined clock products...
This study assesses the capability of the planned NAVSTAR Global Positioning System (GPS) to meet civil navigation requirements. When it becomes operational in about 1983, NAVSTAR GPS will provide accurate two-dimensional and three-dimensional service to ...
The study assesses the capability of the planned NAVSTAR Global Positioning System (GPS) to meet civil navigation requirements. When it becomes operational in about 1988, NAVSTAR GPS will provide accurate two-dimensional and three-dimensional service to a...
Tutorial on how the Global Positioning System (GPS) works. Topics include: triangulation from satellites, measuring distance from a satellite, accurate timing, satellite positions, correction of errors in signal transmission, and differential GPS.
With the initiation of the navigation accuracy prediction algorithm used to estimate the amount of GPS solution (location and time) error for receivers, the capability to accurately predict solution errors due to the major GPS error sources is growing. Al...
A GPS orbit determination software system called Multi-Satellite Orbit Processor (MSOP) has been developed, and uses pseudorange data to determine accurate orbits for the GPS satellite constellation. Methods and strategies specific to the precise orbit de...
A Global Positioning System (GPS) orbit determination software system called the Multi-Satellite Orbit Processor (MSOP) has been developed, and uses pseudo range data to determine accurate orbits for the GPS satellite constellation. Methods and strategies...
... AND CORRECTED ANTENNA COORDINATES IN A LONG-DISTANCE GPS TIME TRANSFER ... 1-1 ACCURATE ANTENNA COORDINATES ...
... The Navstar Global Positioning System (GPS) is an all ... to accurately determine their position, velocity, and ... reference system, anywhere on or near ...
... of GPS receivers and the structure and volatility of the ionosphere. However , it is still significantly more accurate than climatological models. ...
Modern battlefields depend on GPS for precision navigation and timing. Unfortunately, GPS signals are very-low level and GPS interference, both intentional and unintentional, can severely degrade GPS performance. Unmanned Aerial Vehicles (UAV), which have proven their value on the battlefield, rely heavily on ...
NASA Astrophysics Data System (ADS)
Formations of Autonomous Vehicles Using Global Positioning Systems (GPS) Kourosh Rahnamai; Kevin, using a fleet of autonomous R/C (Remote Control) vehicles equipped with Global Positioning Systems (GPS controller. The feedback control system will include only GPS receivers, which will attempt to accurately
Comparison of GPS slant wet delay measurements with model simulations during the passage of a squall line So-Young Ha,1,2 Ying-Hwa Kuo,1 and Yong-Run Guo1 Chris Rocken and Teresa Van Hove GPS a ground- based GPS observation network provide accurate, high- resolution moisture information
Since the successful demonstration of GPS-based Precise Orbit Determination (POD) on TOPEX/Poseidon in 1992, GPS-based POD for Low-Earth Orbiters (LEO) such as the CHAMP and GRACE satellites has become a popular method. The orbit accuracy of GPS-based POD has been improved from 3 cm to 1 cm in the radial direction. In order to achieve ...
An emerging use of GPS is to provide accurate navigation information for satellites in orbit. The GPS satellites are designed to provide service to terrestrial users, so the antenna array points directly towards the Earth and uses a narrow primary beamwid...
The NAVSTAR Global Positioning System (GPS) allows extremely accurate and global determination of time, as well as position and velocity. An STI Time Transfer Unit (TTU) developed for the U.S. Naval Observatory (USNO) has consistently demonstrated the tra...
Accurate absolute position, velocity, attitude and precise relative navigation ... The configured integrated GPS/MEMS IMU system presents a high degree of ...
The Navstar Global Positioning System (GPS) is a highly accurate space based navigation system providing all weather, 24 hour a day service to both military and civilian users. The system provides a Gaussian position solution with four satellites, each pr...
For Global Positioning System (GPS) satellite orbit determination, the most accurate observable available is carrier phase, differenced between observing stations and between satellites to cancel both transmitter and receiver related errors. For maximum a...
The Air Force has equipped its aircraft with avionic systems such as Global Positioning System (GPS) and Inertial Guidance Systems (INS) capable of providing accurate navigation solutions. The aircrews flying these aircraft require a system that can eithe...
For several years, discussions have been ongoing about how to analyze GPS time information in order to get the most accurate and precise time comparison between two locations. Many similar studies were done several years ago before the constellation was d...
Nov 25, 2001 ... Nowadays position on Earth can be found pretty accurately using the global positioning system (GPS) of 24 satellites in precise orbits, ...
... 5e. TASK NUMBER 5f. WORK UNIT NUMBER ... The primary means of accurate time dissemination is the Global Positioning System (GPS). ...
7.2.2 GPS Analysis, IVP Determination, Alignment and SINEX. ... accurate connections and their associated variance covariance matrix, and provided an un- ...
May 9, 2000 ... This targeting operation requires real-time control and accurate real-time knowledge of the spacecraft or aircraft state. ...
Oct 18, 1994 ... Bulldozer operations could become more efficient and accurate using the global positioning system (GPS) and software developed by The Ohio ...
... applied; a few points mapped more accurately with Trimble GPS units with differential correction. Only gates on ... ...
NBII National Biological Information Infrastructure
... N ~ ~ I C mROL OF CESIUM STANDARE ... Cesium-based atomic standards are typically accurate to about seven parts in ten to the twelfth. ...
DGPS equipment is more accurate than the conventional GPS equipment used as navigational aids in automobiles and boats because each antenna sits on top of ...
The Global Positioning System (GPS) uses accurate, stable atomic clocks in satellites and on the ground to provide world-wide position and time ...
... gyro, a Microstrain 3DM electromagnetic compass, and ... to be a comprehensive guide to Kalman Filtering. ... unfamiliar with the Kalman Filter and it's ...
... station clock estimates generally meet or exceed specifications for high- performance cesiums, providing accurate, stable, and reliable clocks in ...
Sep 18, 2009... and highly accurate positioning, attitude, and inertial measurements ... and GPS unit will be directly applicable to Crew Exploration Vehicle, ...
This report contains the results of a Sandia National Laboratories Directed Research and Development (LDRD) program to investigate the integration of Global Positioning System (GPS) and inertial navigation system (INS) technologies toward the goal of optimizing the navigational accuracy of the combined GPSANS system. The approach undertaken is to integrate the data from an ...
The stability of GPS time and frequency transfer is limited by the fact that GPS signals travel through the ionosphere. In high precision geodetic time transfer (i.e. based on precise modeling of code and carrier phase GPS data), the so-called ionosphere-free combination of the code and carrier phase measurements made on the two ...
Global Positioning System (GPS) is an emerging tool for measuring and monitoring both static and dynamic displacement responses of long span cable-supported bridges under gust winds. Since vertical vibration of a long span cable-supported bridge is more significant than its lateral vibration, this paper focuses on the assessment of dynamic displacement measurement accuracy of ...
The major goals and organizational structure of the International GPS Geodynamics Service (IGS), a new Navstar satellite tracking service, are described. IGS activities are aimed at providing the scientific community with data on GPS orbits accurate enough for performing regional and local GPS analysis and daily ...
It is shown that a GPS/INS system integrated by functional partitioning can satisfy all of the RTCA navigation requirements and goals. This is accomplished by accurately calibrating the INS using GPS after the inertial instruments are thermally stabilized and by exploiting the very slow subsequent error growth in the INS information. ...
-antenna GPS receiver to improve the previous work. One estimates vehicle heading (yaw) to eliminate errors and absolute longitudinal velocity using the Global Positioning System (GPS) and Inertial Navigation System vehicle model with single antenna GPS setup. However, out-of-plane vehicle motions due to roll and pitch
GPS observations are sensitive to a wide range of atmospheric, oceanic, hydrologic and solid-Earth processes. Estimating the accuracy of GPS coordinate time series is therefore problematic because it is virtually impossible to know what the �true� answer is since none of these components of the Earth system are fully understood. Traditionally, ...
In order to establish the position of the center of mass of the Earth in the International Celestial Reference Frame, observations of the Global Positioning Satellite (GPS) constellation using the IVS network are important. With a good frame-tie between the coordinates of the IVS telescopes and nearby GPS receivers, plus a common local oscillator reference ...
Global Positioning System (GPS) is an important new technology for spatio-temporal behaviour studies of animals. Differential correction improves location accuracy. Previously, it mostly removed partially the influence of Selective Availability (SA). SA was deactivated in May 2000. The aim of this study was to quantify the influence of SA cancellation on location accuracy of ...
PubMed
This was a project to develop a high-speed rail train navigation system to accurately determine train location, including determining on which of two or more parallel tracks a locomotive is located. The system includes a three-receiver, three-antenna GPS ...
The evaluation to determine whether a Loran system can satisfy the current non-precision approach (NPA), harbor entrance approach (HEA), and timing and frequency requirements was successful. The evaluation was completed under Federal Aviation Administration sponsorship; however, the team�s structure and purpose was multi-modal and multi-organizational. The Loran evaluation team�s purpose was ...
Homogeneously reprocessed GPS data offer the possibility of an accurate, stable, and increasingly long-term record of integrated precipitable water vapor (PW) of particular value in data sparse regions. We present such a global reanalysis of GPS data, focusing on 12 Antarctic sites. We show stepwise improvements of ...
The classical time transfer method used to realize International Atomic Time (TAI) is based on the common view technique, with GPS observations collected by C/A code receivers. The resulting clock offsets between the laboratory clock and GPS time are obtained from a fixed procedure defined by the Consultative Committee for Time and Frequency (CCTF). A ...
This paper presents a new method for improving the accuracy of GPS/IMU/DMI integrated high-precision positioning system mounted on land vehicles. The system comprises a Position and Orientation System (POS) Computer System, an Inertial Measurement Unit (IMU), a Distance Measuring Indicator (DMI) and two Global Positioning System (GPS) antenna. The system ...
Accurate 3D description of the water vapour field is of interest for process studies such as convection initiation. None of the current techniques (LIDAR, satellite, radio soundings, GPS) can provide an all weather continuous 3D field of moisture. The combination of GPS tomography with radio-soundings (and/or LIDAR) has been used for ...
This report describs the results of a PSA contract awarded to SRI International to analyze applications of advanced Global Positioning System (GPS) measurement techniques to provide data for lateral and longitudinal control of AHS vehicles. The report includes: (1) a review of control sensor requirements suggested by other PSA contractors and AHS researchers; (2) an indepth ...
Accurate measurement of physical activity is a pre-requisite to monitor population physical activity levels and design effective interventions. Global Positioning System (GPS) technology offers potential to improve the measurement of physical activity. This paper 1) reviews the extant literature on the application of GPS to monitor ...
PubMed Central
"Today in History - December 8, 1993 - First functional GPS (Global Positioning System) was developed. The technology initially developed for military use eventually made its way into our daily lives- most notably in cars and cell phones. Using information from a number of satellites orbiting the Earth (originally with 24, now a total of 30), a GPS ...
The Global Positioning System (GPS) is a network of satellites, whose original purpose was to provide accurate navigation, guidance, and time transfer to military users. The past decade has also seen rapid concurrent growth in civilian GPS applications, including farming, mining, surveying, marine, and outdoor recreation. One of the ...
. We compare TEC measurements from the NASA Radar Altimeter and DORIS instrument on board TOPEX/POSEIDON with GPS TEC estimates, and evaluate different GPS data analysis strategies. We verify that global tomographic GPS analysis using a voxel grid is well suited for ionospheric calibration of altimeters. We show that a 1-day fit of ...
Continuous GPS networks, typically with a station spacing of about 30km, are still not dense enough to accurately characteristise the dynamics of active faults. Interpolation of these GPS results can improve our understanding of active faults and hence promote related studies. Moreover, even when the networks are densified in order to ...
This paper presents a GPS receiver satellite/antenna selection algorithm for the Stanford Gravity Probe B Relativity Mission. A Trimble Advanced Navigation Sensor Vector receiver onboard the space vehicle, a fourantenna six-channel GPS receiver, will provide real-time navigation solutions for orbit trim and raw measurements for ground post-processing, both ...
It has been pointed out that GPS observation in mountain areas is usually less accurate than that in flat areas, especially in the vertical component, when the height difference among observation sites is large. It is thought that the decrease of accuracy is caused by insufficient corrections for tropospheric delay of the GPS ...
We have developed a sensor system for surface movement aircraft passage. The system is laid underground and can be used though out the whole airport area. It includes a GPS receiver, an accelerometer, an object detection part, and a kind distinction part. The object detection part monitors the decay of GPS signals, and detects passage of an object. Because ...
Undergraduate science majors need practice in critical thinking, quantitative analysis, and judging whether their calculated answers are physically reasonable. Develops exercises using handheld Global Positioning System (GPS) receivers. Reinforces students' abilities to think quantitatively, make realistic "back of the envelope" assumptions, and determine whether their final ...
ERIC Educational Resources Information Center
Soil erosion modeling requires substantial and accurate data to obtain meaningful results for decision-making in soil and water conservation practices. Today's precision farming equipment based on Global Positioning Systems (GPS), enables landowners to gather spatially distributed topographic data i...
Technology Transfer Automated Retrieval System (TEKTRAN)
This project developed and tested a GPS/Inertial Navigation Sensor (INS) that would detect the three-dimensional altitude of a vehicle accurately enough to support advance vehicle control systems. The work involved development of a theory of construction ...
This research develops and attempts to implement a Kalman filter integration of a Phase III Global Positioning System (GPS) five-channel receiver and an LN-94 Inertial Navigation System (INS). The GPS provides highly accurate position and velocity informa...
International diagnostic criteria for depression have been elaborated in order to standardize and to facilitate diagnostic assessment. The findings of the present survey suggest that general practitioners (GPs) do accurately assess the individual depressive symptoms required to fulfill international diagnostic criteria for depressive syndromes. Training ...
The Navstar Global Positioning System (GPS), although primarily designed for three dimensional position and velocity determination, is uniquely capable of providing highly accurate and stable timing information to users. This capability is derived from th...
As part of the targeting process for CAFO (Concentrated Animal Feeding Operation) inspections it is necessary to perform aerial overflights to document potential violators. To accurately document these flight patterns and facility locations, a system was developed and used incor...
EPA Science Inventory
Accurate scoring (miss or impact measurement) of missile intercept tests is required to adequately assess lethality. Instrumentation approaches based on a suite of sensors (e.g., Doppler radar Miss Distance Indicator, optical fiber Photonic Hit Indicator,...
... guidance kit, which converts existing free-fall bombs into accurately guided �smart� weapons. ... The GPS-aided INS mode provides a 13-meter ...
The highly stable, accurate navigation signals provided by the GPS satellite navigation system are utilized in a new time and frequency source presently in the final stages of development. Integration of the latest technology in component quartz oscillato...
A variety of instruments and techniques are used to study and measure the gases in volcanic plumes. Regardless of the approach an accurate measure of plume velocity must be made. Wind measurements made near the elevation of the plume are considerably more...
... accurately copied from the handheld to a desktop computer through the process of synchronization, thus avoiding time and risk of ... in the handheld have priority during the synchronization process, such ...
The integration of vision sensors and inertial navigation system (INS) can enable precision navigation capabilities in the absence of GPS. Inspired from biological systems, a multi-aperture vision processing system allows for accurate self-motion (egomoti...
Minnesat is the micro-satellite that was designed by the University of Minnesota as part of UNP-4. The mission of Minnesat was to validate the use carrier phase GPS technology to mechanize a compact and accurate attitude determination system. In a broader...
This paper offers arguments to support the contention that a differential GPS measurement system is required for missile intercept flight testing. Simply stated there is no other system capable of sufficiently accurate relative 3-dimensional position meas...
2001 Han, S.-C., J. Kwon, and C. Jekeli, Accurate absolute GPS positioning through satellite clock error estimation, Journal of Geodesy, 75, 33-43, 2001. ...
Global Positioning Systems (GPS) are a location determination technology that offers significance opportunities for obtaining highly accurate locational data at low costs. n order for the technology to perform up to its capabilities in Agency applications, Environmental Protectio...
Barbara and David Tewksbury, Hamilton College Summary In this exercise, students process LiDAR data for the Hamilton College campus area to determine accurate elevations of wellheads of sampling wells on campus. ...
, laser and ultrasonic rangefinders, optical mouse sensors, and accelerometers. Methods will also be discussed for calculating position from accelerometer data with a discussion of current results and future plans for combining GPS and accelerometer data. Index Terms- Position, Tracking, Localization
The major problem addressed by this research is the large and/or expensive equipment required by a conventional navigation system to accurately determine the position of an Autonomous Underwater Vehicle (AUV) during all phases of an underwater search or m...
Han, S.-C., J. Kwon, and C. Jekeli, Accurate absolute GPS positioning through satellite clock error estimation, Journal of Geodesy, 75, 33-43, 2001. ...
Autonomous underwater vehicle navigation is a complex problem of state estimation. Accurate navigation is made difficult due to a lack of reference navigation aids or use of the Global Positioning System (GPS) that could establish the vehicles position. A...
User equipment for LEO spacecraft positioning using Navsat and GPS is defined, and a development approach is outlined. It is concluded that both systems are cost effective. When the high performance P-Code receiver is required, the implementation of exist...
...sponsor. (2) Description of project and site in terms of: (i) Project location, including global positioning system (gps) coordinates accurate to within 10 meters. (ii) Project purpose. (iii) Proposed quantity of water to be...
Code of Federal Regulations, 2011
The Global Positioning System (GPS) enables precise and accurate determination of position anywhere on anywhere on the Earth, a boon to the field of geodesy. Although great advances in geodetic GPS positioning precision and accuracy have been made over the last decade, improvements can still be made. This dissertation addresses ...
The goal of the NASA Space Launch Initiative (SLI) program is to advance the technologies for the next generation reusable launch vehicle (RLV). The SLI program has identified automated rendezvous and docking as an area requiring further research and development. Currently, the Space Shuttle uses a partially manual system for rendezvous, but a fully automated system could be safer and more ...
The capabilities of the Global Positioning System (GPS) for accurately determining geodetic quantities are well established. Nevertheless, no comparison between deflections of the vertical as determined through GPS with leveling and values conventionally computer by astrogeodetic methods has yet been published. This investigation ...
