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This article is from Nucleic Acids Research , volume 42 . Abstract Development of tools to jointly visualize the genome and the epigenome remains a challenge. chroGPS is a computational approach that addresses this question. chroGPS uses multidimensional scaling techniques to represent similarity between epigenetic factors, or between genetic elements on the basis of their epigenetic state, in 2D/3D reference maps. We emphasize biological interpretability, statistical robustness, integration of genetic and epigenetic data from heterogeneous sources, and computational feasibility. Although chroGPS is a general methodology to create reference maps and study the epigenetic state of any class of genetic element or genomic region, we focus on two specific kinds of maps: chroGPSfactors, which visualizes functional similarities between epigenetic factors, and chroGPSgenes, which describes the epigenetic state of genes and integrates gene expression and other functional data. We use data from the modENCODE project on the genomic distribution of a large collection of epigenetic factors in Drosophila, a model system extensively used to study genome organization and function. Our results show that the maps allow straightforward visualization of relationships between factors and elements, capturing relevant information about their functional properties that helps to interpret epigenetic information in a functional context and derive testable hypotheses.

'GLOBAL POSITIONING SYSTEM AT STATIONS . (27-Jul-2006)' from the Parliament Digital Library

'Functioning of Global Positioning System (20-Dec-1991)' from the Parliament Digital Library

The International GPS (Global Positioning System) Service for Geodynamics (IGS) began formal operation on January 1, 1994. This first annual report is divided into sections, which mirror different aspects of the service. Section (1) contains general information, including the history of the IGS, its organization, and the global network of GPS tracking sites; (2) contains information on the Central Bureau Information System; (3) describes the International Earth Rotation Service (IERS); (4) details collecting and distributing IGS data in Data Center reports; (6) describes how the IGS Analysis Centers generate their products; (7) contains miscellaneous contributions from other organizations that share common interests with the IGS.

The LinCom effort in supporting the JSC study of the use of the Global Positioning System (GPS) on the space shuttle and in Ku-band problem investigation is documented. LinCom was tasked to evaluate system implementation, performance, and integration aspects of the shuttle GPS and to provide independent technical assessment of reports submitted to JSC regarding integration studies, system studies and navigation analyses.

The results of flight tests to determine the feasibility of using the Global Positioning System (GPS) in the differential mode (DGPS) to provide high accuracy, precision navigation, and guidance for helicopter approaches to landing are presented. The airborne DGPS receiver and associated equipment is installed in a NASA UH-60 Black Hawk helicopter. The ground-based DGPS reference receiver is located at a surveyed test site and is equipped with a real-time VHF data link to transmit correction information to the airborne DGPS receiver. The corrected airborne DGPS information, together with the preset approach geometry, is used to calculate guidance commands which are sent to the aircraft's approach guidance instruments. The use of DGPS derived guidance for helicopter approaches to landing is evaluated by comparing the DGPS data with the laser tracker truth data. Both standard (3 deg) and steep (6 deg and 9 deg) glideslope straight-in approaches were flown. DGPS positioning accuracy based on a time history analysis of the entire approach was 0.2 m (mean) +/- 1.8 m (2 sigma) laterally and -2.0 m (mean) +/- 3.5 m (2 sigma) vertically for 3 deg glideslope approaches, -0.1 m (mean) +/- 1.5 m (2 sigma) laterally and -1.1 m (mean) +/- 3.5 m (2 sigma) vertically for 6 deg glideslope approaches and 0.2 m (mean) +/- 1.3 m (2 sigma) laterally and -1.0 m (mean) +/- 2.8 m (2 sigma) vertically for 9 deg glideslope approaches. DGPS positioning accuracy at the 200 ft decision height (DH) on a standard 3 deg slideslope approach was 0.3 m (mean) +/- 1.5 m (2 sigma) laterally and -2.3 m (mean) +/- 1.6 m (2 sigma) vertically. These errors indicate that the helicopter position based on DGPS guidance satisfies the International Civil Aviation Organization (ICAO) Category 1 (CAT 1) lateral and vertical navigational accuracy requirements.

The Deep Space Network (DSN) has a requirement to maintain knowledge of the frequency offset between DSN stations within 3 x 10 to the -13th power and time offset within 10 microseconds. It is further anticipated that in the 1987-1990 era the requirement for knowledge of time offset between DSN stations will be less than 10 nanoseconds. The Jet Propulsion Laboratory (JPL) is using the Global Positioning System (GPS) Space Vehicles, as a development project, to transfer time and frequency over intercontinental distances between stations of the DSN and between the DSN and other agencies. JPL has installed GPS timing receivers at its tracking station near Barstow, California and at its tracking station near Madrid, Spain. The details of the experiment and the data are reported. There is a discussion of the ultimate capabilities of these techniques for meeting the functional requirements of the DSN.

The application of GPS to spacecraft attitude determination is a new and growing field. Although the theoretical literature is extensive, space flight testing is currently sparse and inadequate. As an operations organization, the Flight Dynamics Division (FDD) has the responsibility to investigate this new technology, and determine how best to implement the innovation to provide adequate support for future missions. This paper presents some of the current efforts within FDD with regard to GPS attitude determination. This effort specifically addresses institutional capabilities to accommodate a new type of sensor, critically evaluating the literature for recent advancements, and in examining some available -albeit crude- flight data.

A real-time global positioning system (GPS) Kalman filter has been developed to support automated rendezvous with the International Space Station (ISS). The filter is integrated with existing Shuttle rendezvous software running on a 486 laptop computer under Windows. In this work, we present real-time and postflight results achieved with the filter on STS-69. The experiment used GPS data from an Osborne/Jet propulsion Laboratory TurboRouge receiver carried on the Wake Shield Facility (WSF) free flyer and a Rockwell Collins 3M receiver carried on the Orbiter. Real time filter results, processed onboard the Shuttle and replayed in near-time on the ground, are based on single vehicle mode operation and on 5 to 20 minute snapshots of telemetry provided by WSF for dual-vehicle mode operation. The Orbiter and WSF state vectors calculated using our filter compare favorably with precise reference orbits determined by the University of Texas Center for Space Research. The lessons learned from this experiment will be used in conjunction with future experiments to mitigate the technology risk posed by automated rendezvous and docking to the ISS.

The Coast Guard has begun an initiative to deploy a nationwide Differential Global Positioning System (DGPS) to support Coast Guard missions and to enhance maritime safety in harbor navigation. DGPS service is expected to provide accuracy to within ten meters (95% of the time) to suitably equipped vessels. It would do this by broadcasting corrections to GPS navigation satellite signals, thereby improving accuracy by a factor of ten over standard GPS. The primary emphasis of this thesis is to show how decision making and planning for the DGPS project may be aided by comparing technological alternatives using Cost Effectiveness Analysis (CEA). This method is essentially a means of quantifying effectiveness per dollar of cost. The author consolidates the discussion of key issues within one document, identifies the technical decision criteria, estimates alternative system life-cycle costs, and makes a preliminary finding as to the merits of radiobeacon transmission over a dedicated satellite channel. In order to quantify effectiveness, many performance criteria are consolidated under five figures of merit : accuracy, availability, coverage, integrity, and adaptability. The inclusion of user equipment prices in life-cycle costs proves to be critical to the preliminary finding in favor of the radiobeacon-based alternative. This CEA model is especially suited to decision making in an environment of technological and policy change, since it can be easily refined and updated over the predicted four-year implementation period. (Author)

The Coast Guard has begun an initiative to deploy a nationwide Differential Global Positioning System (DGPS) to support Coast Guard missions and to enhance maritime safety in harbor navigation. DGPS service is expected to provide accuracy to within ten meters (95% of the time) to suitably equipped vessels. It would do this by broadcasting corrections to GPS navigation satellite signals, thereby improving accuracy by a factor of ten over standard GPS. The primary emphasis of this thesis is to show how decision making and planning for the DGPS project may be aided by comparing technological alternatives using Cost Effectiveness Analysis (CEA). This method is essentially a means of quantifying effectiveness per dollar of cost. The author consolidates the discussion of key issues within one document, identifies the technical decision criteria, estimates alternative system life-cycle costs, and makes a preliminary finding as to the merits of radiobeacon transmission over a dedicated satellite channel. In order to quantify effectiveness, many performance criteria are consolidated under five figures of merit : accuracy, availability, coverage, integrity, and adaptability. The inclusion of user equipment prices in life-cycle costs proves to be critical to the preliminary finding in favor of the radiobeacon-based alternative. This CEA model is especially suited to decision making in an environment of technological and policy change, since it can be easily refined and updated over the predicted four-year implementation period. (Author)

This item represents a case in PACER, the U.S. Government's website for federal case data. If you wish to see the entire case, please consult PACER directly.

A GPSPAC/LANDSAT-D Interface (GLI) Ground Support System was built to validate the performance and to calibrate the accuracy of the experimental navigation package, GPSPAC, flown on the LANDSAT-4 and 5 spacecraft. Although the GLI system operated successfully to give the orbit information needed to validate the GPSPAC, it also detected two anomalies: one is characteristic of the GLI system and the other is characteristic of the pre-operational phase of GPS. Several methods were applied to resolve or reduce the anomalies. This paper presents a description of the problems, the methods applied to resolve or reduce them, and the results.

This is the final report on the Texas Instruments Incorporated (TI) simulations study of Spacecraft Application of Advanced Global Positioning System (GPS) Technology. This work was conducted for the NASA Johnson Space Center (JSC) under contract NAS9-17781. GPS, in addition to its baselined capability as a highly accurate spacecraft navigation system, can provide traffic control, attitude control, structural control, and uniform time base. In Phase 1 of this program, another contractor investigated the potential of GPS in these four areas and compared GPS to other techniques. This contract was for the Phase 2 effort, to study the performance of GPS for these spacecraft applications through computer simulations. TI had previously developed simulation programs for GPS differential navigation and attitude measurement. These programs were adapted for these specific spacecraft applications. In addition, TI has extensive expertise in the design and production of advanced GPS receivers, including space-qualified GPS receivers. We have drawn on this background to augment the simulation results in the system level overview, which is Section 2 of this report.

As the development of the NAVSTAR Global Positioning System (GPS) continues, there will increasingly be the need for a software centered signal model. This model must accurately generate the observed pseudorange which would typically be encountered. The observed pseudorange varies from the true geometric (slant) range due to range measurement errors. Errors in range measurement stem from a variety of hardware and environment factors. These errors are classified as either deterministic or random and, where appropriate, their models are summarized. Of particular interest is the model for Selective Availability which is derived from actual GPS data. The procedure for the determination of this model, known as the System Identification Theory, is briefly outlined. The synthesis of these error sources into the final signal model is given along with simulation results.

The Global Positioning System (GPS) provides users autonomous, real-time navigation capability. A vehicle equipped with GPS user equipment can receive and process signals transmitted by a constellation of GPS satellites and derive from the resulting measurements the vehicle's position and velocity. Specified accuracies range from 16 to 76 meters and 0.1 to 1.0 meters/second for position and velocity, respectively. In a rendezvous and docking scenario, the use of a technique called relative GPS can provide range and range rate accuracies on the order of 1 meter and 0.01 meters/second, respectively. Relative GPS requires both vehicles to be equipped with GPS user equipment and a data communication link for transmission of GPS data and GPS satellite selection coordination information. Through coordinated satellite selection, GPS measurement errors common to both users are cancelled and improved relative position and velocity accuracies are achieved. The background, the design approach, the expected performance and capabilities, the development plan, and the project status are described. In addition, a description of relative GPS, the possible GPS hardware and software configurations, and its application to automated rendezvous and capture are presented.

A geostationary reference satellite (REFSAT) that broadcasts every four seconds updated GPS satellite coordinates was developed. This procedure reduces the complexity of the GPS receiver. The economic and performance payoffs associated with replacing maritime stripborne navigation systems with NAVSTAR was quantified and the use of NAVSTAR for measurements of ocean currents in the broad ocean areas of the world was evaluated.

The International Space Station global positioning system (GPS) receiver was activated in April 2002. Since that time, numerous software anomalies surfaced that had to be worked around. Some of the software problems required waivers, such as the time function, while others required extensive operator intervention, such as numerous power cycles. Eventually enough anomalies surfaced that the three pieces of code included in the GPS unit have been re-written and the GPS units upgraded. The technical aspects of the problems are discussed, as well as the underlying causes that led to the delivery of a product that has had so many problems. The technical aspects of the problems included physical phenomena that were not well understood, such as the affect that the ionosphere would have on the GPS measurements. The underlying causes were traced to inappropriate use of legacy software, changing requirements, inadequate software processes, unrealistic schedules, incorrect contract type, and unclear ownership responsibilities..

The International Space Station global positioning system (GPS) receiver was activated in April 2002. Since that time, numerous software anomalies surfaced that had to be worked around. Some of the software problems required waivers, such as the time function, while others required extensive operator intervention, such as numerous power cycles. Eventually enough anomalies surfaced that the three pieces of code included in the GPS unit have been re-written and the GPS units upgraded. The technical aspects of the problems are discussed, as well as the underlying causes that led to the delivery of a product that has had so many problems. The technical aspects of the problems included physical phenomena that were not well understood, such as the affect that the ionosphere would have on the GPS measurements. The underlying causes were traced to inappropriate use of legacy software, changing requirements, inadequate software processes, unrealistic schedules, incorrect contract type, and unclear ownership responsibilities..

Understanding The GPS An Introduction to the Global Positioning System Gregory French

'Global Positioning System (2-Dec-2004)' from the RS Debates Digital Library

The NASA/USAF program on the Environmental Charging of Spacecraft Surfaces consists, in part, of experimental efforts directed toward evaluating the response of materials to the environmental charged particle flux. Samples of thermal blankets of the type to be used on the Global Positioning System Flight Space Vehicles were tested to determine their response to electron flux. The primary result observed was that no discharges were obtained with the quartz-fiber-fabric-covered multilayer insulation specimen. The taped aluminized polyester grounding system used on all specimens did not appear to grossly deteriorate with time; however, the specimens require specific external pressure to maintain constant grounding system resistance.

Modern spacecraft tracking and navigation require highly accurate Earth-orientation parameters. For near-real-time applications, errors in these quantities and their extrapolated values are a significant error source. A globally distributed network of high-precision receivers observing the full Global Positioning System (GPS) configuration of 18 or more satellites may be an efficient and economical method for the rapid determination of short-term variations in Earth orientation. A covariance analysis using the JPL Orbit Analysis and Simulation Software (OASIS) was performed to evaluate the errors associated with GPS measurements of Earth orientation. These GPS measurements appear to be highly competitive with those from other techniques and can potentially yield frequent and reliable centimeter-level Earth-orientation information while simultaneously allowing the oversubscribed Deep Space Network (DSN) antennas to be used more for direct project support.

This report treats the application of the NAVSTAR/Global Positioning System as the Position/Location System in Real Time Casualty Assessment experiments. The desirable characteristics of a position/location system are listed. A current position/location system, the Range Measuring System, is used as a comparison reference for the Global Positioning System. Operation and parameters of the Global Positioning System are presented. A description and the results of a five day demonstration conducted on an instrumented range using a Global Positioning System prototype receiver are given. It is concluded that the Global Positioning System has some important advantages and that more study and further tests are needed to determine the full extent of its potential. (Author)

This case uses the development of the Global Positioning System (GPS) to help students develop skills related to decision-making using cost-benefit analysis (CBA). It is the purpose of cost-benefit analysis to weigh the benefits (or justification) of an investment or policy against the potential costs of the investment (or other alternatives). This case is intended for courses in public policy evaluation and those that consider the economic analysis of risk and uncertainty.

The Goddard Space Flight Center Flight Dynamics and Mission Operations Divisions have jointly investigated the feasibility of engineering modular Global Positioning SYSTEM (GPS) navigation software to support both real time flight and ground postprocessing configurations. The goals of this effort are to define standard GPS data interfaces and to engineer standard, reusable navigation software components that can be used to build a broad range of GPS navigation support applications. The paper discusses the GPS modular software (GMOD) system and operations concepts, major requirements, candidate software architecture, feasibility assessment and recommended software interface standards. In additon, ongoing efforts to broaden the scope of the initial study and to develop modular software to support autonomous navigation using GPS are addressed,

An improved Global Positioning em antenna adaptor allows fixed antenna height measurements by removably attaching an adaptor plate to a conventional surveyor's tripod. Antenna height is controlled by an antenna boom which is a fixed length rod. The antenna is attached to one end of the boom. The opposite end of the boom tapers to a point sized to fit into a depression at the center of survey markers. The boom passes through the hollow center of a universal ball joint which is mounted at the center of the adaptor plate so that the point of the rod can be fixed in the marker's central depression. The mountains of the ball joint allow the joint to be moved horizontally in any direction relative to the tripod. When the ball joint is moved horizontally, the angle between the boom and the vertical changes because the boom's position is fixed at its lower end. A spirit level attached to the rod allows an operator to determine when the boom is plumb. The position of the ball joint is adjusted horizontally until the boom is plumb. At that time the antenna is positioned exactly over the center of the monument and the elevation of the antenna is precisely set by the length of the boom.

The Global Positioning System (GPS) has become a useful tool in providing relative survey control. The relative positioning accuracies of the GPS are commonly on the order of 1-10 parts per million (ppm). The drawback with relative positioning is the user must have one or more known control stations. In areas like the Continental United States (CONUS), survey control is abundant. However, in the near future, the Corps of Engineers may be asked to provide engineering and mapping support to countries which have limited or nonexistent geodetic control networks. In these areas, the engineer and surveyor will not have known control to initiate a survey. In this case, the surveyor will be required to establish one or more absolute control points. To achieve absolute positional accuracies of 1-3 meters, the user must occupy the unknown station for 4-6 hours. The data reduction would take place at the Defense Mapping Agency (DMA), Washington, DC, and the user could wait for several weeks to receive the adjusted coordinates. Recently, USAETL adapted the absolute positioning program created by DMA to run on a standard IBM XT or compatible personal computer. After a few hours of data collection, the absolute positioning program CORPSABS allows the user to estimate the three dimensional position within a matter of minutes. The positioning results can be refined when the DMA precise ephemerides become available. This paper quantifies the accuracy of absolute GPS positioning and evaluates its application to the civilian sectors of the Corps of Engineers.

The Global Positioning System (GPS) has become a useful tool in providing relative survey control. The relative positioning accuracies of the GPS are commonly on the order of 1-10 parts per million (ppm). The drawback with relative positioning is the user must have one or more known control stations. In areas like the Continental United States (CONUS), survey control is abundant. However, in the near future, the Corps of Engineers may be asked to provide engineering and mapping support to countries which have limited or nonexistent geodetic control networks. In these areas, the engineer and surveyor will not have known control to initiate a survey. In this case, the surveyor will be required to establish one or more absolute control points. To achieve absolute positional accuracies of 1-3 meters, the user must occupy the unknown station for 4-6 hours. The data reduction would take place at the Defense Mapping Agency (DMA), Washington, DC, and the user could wait for several weeks to receive the adjusted coordinates. Recently, USAETL adapted the absolute positioning program created by DMA to run on a standard IBM XT or compatible personal computer. After a few hours of data collection, the absolute positioning program CORPSABS allows the user to estimate the three dimensional position within a matter of minutes. The positioning results can be refined when the DMA precise ephemerides become available. This paper quantifies the accuracy of absolute GPS positioning and evaluates its application to the civilian sectors of the Corps of Engineers.

Lockheed Martin was awarded a contract at the end of 1995 by the US Air Force to upgrade the space lift range infrastructure at Cape Canaveral Air Force Station in Florida and Vandenberg Air Force Base in California. The goal of the RSA Program is to reduce the total cost per launch while meeting the Range safe@ requirements. This will be accomplished on both coasts by adopting industry standards and replacing antiquated instruments with Commercial-of-the-Shelf (COTS) equipment. Furthermore, common operation and maintenance procedures will be developed for both ranges in order to reduce the total life cycle cost and subsequent operation and maintenance expenses at both ranges. The purpose of this paper is to present the overall system requirements and system architecture for the three timing product subsystems.

As the number of civilian users of the United States Air Force's Navstar Global Positioning System (GPS) continues to increase at such a staggering rate, the government's exposure to potential liability also increases. The purpose of this thesis is to establish a legal framework to apply to GPS-related claims against the United States, primarily against the Air Force as operator of the system. Part I consists of three chapters. Following an introductory chapter, Chapter II describes the system and the general characteristics of GPS. Chapter III outlines the military uses of the system and the increasing and evolving civilian uses. Part II discusses the liability ramifications of providing GPS services for civilian use. Chapter IV provides the statutory bases for the U.S. government's traditional role in regulating civil aviation and maritime navigation. Chapter V analyzes the applicable domestic law under the existing statutes waiving the sovereign immunity of the United States, and Chapter VI looks at liability under international law. Chapter VII then draws some general conclusions as to how the existing law may apply to the government in regulating GPS use and operating the system itself.

In April of 1973, a memorandum issued by the Deputy Secretary of Defense consolidated two experimental satellite navigation programs into one effort: The NAVSTAR Global Positioning System was born. After 22 years and $8 billion dollars, the system was finally declared fully operational in 1995. In 1983, a Reagan Administration directive authorized civilian use of the system. Evidence, however, shows that civil access to GPS was intended all along. Since the Reagan decision, the civil market has grown exponentially, and is predicted to exceed $8 billion in the year 2000. By 1995 alone, civil users outnumbered military users by ten to one. while civil access is permitted, its users are subject to an intentionally degraded signal called selective availability that restricts accuracy to 100 meters. Civil users resent the degradation policy and have resorted to differential GPS techniques to evade the accuracy restrictions. Some commercial providers claim their subscription services allow accuracies close to 45 centimeters. The Department of Transportation is also in the differential GPS business, providing maritime and aviation augmentations. By Presidential decision, selective availability will be removed within ten years. Examining the Department of Defense's initial vision, the forces behind the granting of commercial access, and the current state of GPS implementation, the study attempts to determine the effects of commercialization on military use of the system. Has GPS provided all the benefits its designers envisioned? Has civil access degraded its military utility, or has it actually enhanced its military role? Considering these issues, it becomes apparent that the growth of GPS has seen tremendous cost reductions and innovation in applications of the technology. Although the growth of civil users has created some difficulties for DoD, civil access has actually enhanced DoD's ability to field the system and procure user equipment.

At the 2000 World Radio Conference (WRC), a European initiative resulted in the approval of resolutions 605 and 606 (agenda item 1.15), which the United States opposed. These resolutions established provisional power flux density (PFD) limits on the L2 and L5 frequencies of the Global Positioning System. These limits will negatively affect the $1.2B GPS modernization. The United States will have to present its positions and rationale regarding the PFD limits to international meetings, including the 2003 World Radio Conference, to persuade the international community to adopt that U.S. view. Developing the U.S. view and conducting the supporting technical work for the World Radio Conference is accomplished through a domestic interagency U.S. process called the International Telecommunications Advisory Committee (ITAC) process. In this process, the interests and efforts of numerous agencies must be coordinated to produce a focused and cohesive argument. Accomplishing this is not easy. In fact, several players in the ITAC process working issues surrounding WRC resolutions 605 and 606 have encountered considerable difficulty reaching agreement and submitting technical contributions internationally. An analysis of the ITAC process using coordination theory reveals that the problem stems from coequal participants attempting to coordinate directly conflicting interests in a consensus-based process. The problem is further complicated by the geographic separation of the parties. Several remedial actions are available, including using a third-party to arbitrate directly conflicting issues and co-locating the parties.

The U.S. Army Aviation Technical Test Center (ATTC) conducted the methodology investigation of the global positioning system (GPS) vehicle tracking system at White Sands Missile Range from June 1995-April 1996. The objectives were to quantify the accuracy of the GPS tracking system throughout the dynamics of normal helicopter flight and ensure that the rotor effect on the GPS signal reception is considered. It was concluded that the system as tested is capable of tracking helicopters through their flight envelope to an accuracy of less than 2 feet spherical error probable in real time, and the rotor system appeared to have little effect on the GPS signals.

'GLOBAL POSITIONING SYSTEM (11-Aug-2006)' from the Parliament Digital Library

'GLOBAL POSITIONING SYSTEM (11-Aug-2006)' from the Parliament Digital Library

This paper summarizes a study on the uses of the NAVSTAR Global Positioning System (GPS) at the National Ranges operated by the United States Army, Navy, and Air Force for weapon system development, test, and training. The primary objectives were to evaluate GPS application areas, identify and analyze technical issues, and recommend cost- and mission effective applications. The study found that GPS technology will have a wide variety of use at the ranges with significant cost advantages and that the technical issues, some of which are quite challenging, do not pose serious obstacles to widespread employment. It will be necessary to design and develop a new family of GPS receiver hardware for range uses since the current generation of receivers does not satisfy the accuracy, data rate and continuity, and size demands of the typical range environment. The study provided the family definitions for GPS range equipment and the basis for a joint-service development program under Air Force direction at Eglin AFB, FL.

U.S. Coast Guard mission is to daily conduct law enforcement in the dynamic and challenging maritime environment. Rapid advances in technology have the potential to dramatically improve the organization's capacity to conduct this mission. The ability to track and monitor suspect vessels, as well as the law enforcement personnel that board them, is a critical next step in the evolution of Maritime Interdiction. With the development of the Global Positioning System (GPS) and downward trend of GPS receiver costs and their form size, it is now possible to integrate positioning technology with software collaborative tools and wireless networking. The power of collaboration tools and real time positioning data offers the potential to deliver an entirely new and unique level of situational awareness to the law enforcement teams on the water as well as the command and control structure shore side. No longer does VHF radio need to be the sole form of communication between operational personnel and their commands. This thesis discusses the specific methods available for tagging and tracking individuals and vessels and explore the challenger and feasibility of deploying these technologies in the maritime environment.

Satellites are the only major Air Force systems with no maintenance, routine repair, or upgrade capability. The result is expensive satellites and a heavy reliance on access to space. At the same time, satellite design is maturing and reducing the cost to produce satellites with longer design lives. This works against the ability to keep the technology on satellites current without frequent replacement of those satellites. The Global Positioning System Joint Program Office realizes that it must change its mode of operations to quickly meet new requirements while minimizing cost. The possibility of using robotic servicing architectures to solve these problems is considered in this thesis. The authors accomplished this through a systems engineering and decision analysis approach in which a number of different alternatives for on-orbit satellite repair and upgrade were analyzed. This approach involved defining the problem framework and desired user benefits, then developing different system architectures and determining their performance with regard to the specified benefits. Finally, the authors used decision analysis to evaluate the alternative architectures in the context of the user's goals. The results indicate favorable benefit-to-cost relationships for on-orbit servicing architectures as compared to the current mode of operation.

Programs to examine and develop means to utilize the global positioning system (GPS) for civil aviation functions are described. User requirements in this regard are discussed, the development of technologies in the areas of antennas, receivers, and signal processors for the GPS are examined, and modifications to the GPS to fit operational and design criteria are evaluated.

On April 9, 2004, the acting USD (AT&L) and the ASD (NII) jointly requested that the Defense Science Board undertake a Task Force on the future of the Global Positioning System (GPS). The request focused on the implications for GPS from a civil-commercial Galileo, the European Union's proposed Global Navigation Satellite System (GNSS). The Terms of Reference also requested assessment of several other aspects of GPS military and commercial competitiveness and of upgrade strategies and technical alternatives. The DSB empanelled a Task Force comprised of GPS experts with extensive public and private sector experience. Deliberations on relevant GPS topics were conducted primarily among the Task Force members with outside briefings limited to current activities affecting the program itself and other directly relevant topics. During the course of the year several outside events significantly modified the issues of uncertainty that had existed when the Task Force was formed. Those events included the signing of a cooperative agreement on GPS and Galileo between the United States and the European Union in June 2004, a major study on GPS commercial viability as approved by the Deputy Secretary of Defense in October 2004 and signature by the President of an updated national policy on GPS and related systems in December 2004. While each of these events moderated specific areas of uncertainty that had been complicating GPS planning, each is still a work in progress that will require monitoring as leadership moves to address the still substantive issues facing GPS operation and evolution.

This report examines the technical feasibility of alternate waveforms to perform the GPS functions and to result in less complex receivers than is possible with the GPS C/A waveform. The approach taken to accomplish this objective is (a) to identify, after a quick broad overview, a few promising waveforms, (b) to complete the architectural synthesis of a GPS system based on the new waveforms, (c) to analyze the performance of these systems in providing ranging and communication capability and (d) to assess the impact on receiver hardware and software. One conclusion is that the class of pulsed waveform, when combined with emerging matched filter technology, permits the use of a greatly simplified receiver design. A major part of the report consists of description of a pulse-based GPS design. Although very specific, the design was intended as a vehicle for performance analysis only and many refinements and alternatives within the same class are possible. Other classes of waveforms such as tone ranging and chirped FM waveforms, although adequate, do not seem superior to the present PN encoded CW waveform for GPS. Finally, if the 'alternate' waveform is simply the present C/A waveform but with a substantially increased power level, it is shown that with the present designs the performance will be greatly increased or, alternatively, performance margin can be traded for a simplified receiver implementation. (Author)

This experiment demonstrated the obtainable accuracy for estimating changes in a receiver antenna position using Doppler techniques and the NAVSTAR Global Positioning System (GPS). The antenna was periodically moved to three locations approximately 2 to 3 meters apart. The moves occurred within a one minute Doppler count interval every fifteenth interval until at least six Doppler measurements were made for each location change. These measurements were used to determine the observed change in range from the antenna to the GPS satellite due only to the movement of the antenna. The calculated change in range was computed from the surveyed distance moved and the angular differences in elevation and azimuth between the direction of the move and the direction of the satellite. The observed and calculated changes in range were compared. The three-dimensional antenna position changes were estimated using six observed change in range measurements for each location change. The estimated results were compared with surveyed values and demonstrated subdecimeter accuracy. (Author)

This experiment demonstrated the obtainable accuracy for estimating changes in a receiver antenna position using Doppler techniques and the NAVSTAR Global Positioning System (GPS). The antenna was periodically moved to three locations approximately 2 to 3 meters apart. The moves occurred within a one minute Doppler count interval every fifteenth interval until at least six Doppler measurements were made for each location change. These measurements were used to determine the observed change in range from the antenna to the GPS satellite due only to the movement of the antenna. The calculated change in range was computed from the surveyed distance moved and the angular differences in elevation and azimuth between the direction of the move and the direction of the satellite. The observed and calculated changes in range were compared. The three-dimensional antenna position changes were estimated using six observed change in range measurements for each location change. The estimated results were compared with surveyed values and demonstrated subdecimeter accuracy. (Author)

This report presents the results of the cost analysis of avionics required in support of the civil application of the Global Positioning System (GPS). The design considered for analysis was chosen because of the advanced state of development which provided the necessary data for cost evaluations. The costs of avionics were developed using both the parametric and accounting methods of cost estimating. (Author)

Daily estimates of the Earth's pole position were obtained with the Global Positioning System (GPS) by using measurements obtained during the GPS IERS (International Earth Rotation Service) and Geodynamics (GIG'91) experiment from 22 Jan. to 13 Feb. 1991. Data from a globally distributed network consisting of 21 Rogue GPS receivers were chosen for the analysis. A comparison of the GPS polar motion series with nine 24-hour very long baseline interferometry (VLBI) estimates yielded agreement in the day-to-day pole position of about 1.5 cm for both X and Y polar motion. A similar comparison of GPS and satellite laser ranging (SLR) data showed agreement to about 1.0 cm. These preliminary results indicate that polar motion can be determined by GPS independent of, and at a level comparable to, that which is obtained from either VLBI or SLR. Furthermore, GPS can provide these data with a daily frequency that neither alternative technique can readily achieve. Thus, GPS promises to be a powerful tool for determining high-frequency platform parameter variation, essential for the ultraprecise spacecraft-tracking requirements of the coming years.

'NATIONAL PROGRAMME ON GLOBAL POSITIONING SYSTEM (7-Aug-2001)' from the Parliament Digital Library

Using meteorology data, focusing on precipitable water (PW), obtained during the 2000-2003 thunderstorm seasons in Central Florida, this paper will, one, assess the skill and accuracy measurements of the current Mazany forecasting tool and, two, provide additional forecasting tools that can be used in predicting lightning. Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS) are located in east Central Florida. KSC and CCAFS process and launch manned (NASA Space Shuttle) and unmanned (NASA and Air Force Expendable Launch Vehicles) space vehicles. One of the biggest cost impacts is unplanned launch scrubs due to inclement weather conditions such as thunderstorms. Each launch delay/scrub costs over a quarter million dollars, and the need to land the Shuttle at another landing site and return to KSC costs approximately $ 1M. Given the amount of time lost and costs incurred, the ability to accurately forecast (predict) when lightning will occur can result in significant cost and time savings. All lightning prediction models were developed using binary logistic regression. Lightning is the dependent variable and is binary. The independent variables are the Precipitable Water (PW) value for a given time of the day, the change in PW up to 12 hours, the electric field mill value, and the K-index value. In comparing the Mazany model results for the 1999 period B against actual observations for the 2000-2003 thunderstorm seasons, differences were found in the False Alarm Rate (FAR), Probability of Detection (POD) and Hit Rate (H). On average, the False Alarm Rate (FAR) increased by 58%, the Probability of Detection (POD) decreased by 31% and the Hit Rate decreased by 20%. In comparing the performance of the 6 hour forecast period to the performance of the 1.5 hour forecast period for the Mazany model, the FAR was lower by 15% and the Hit Rate was higher by 7%. However, the POD for the 6 hour forecast period was lower by 16% as compared to the POD of the 1.5 hour forecast period. Neither forecast period performed at the accuracy measures expected. A 2-Hr Forecasting Tool was developed to support a Phase I Lightning Advisory, which requires a 30-minute lead time for predicting lightning.

A Global Positioning System (GPS) receiver having a number of channels, receives an aggregate of pseudorange code time division modulated signals. The aggregate is converted to baseband and then to digital form for separate processing in the separate channels. A fast fourier transform processor computes the signal energy as a function of Doppler frequency for each correlation lag, and a range and frequency estimator computes estimates of pseudorange, and frequency. Raw estimates from all channels are used to estimate receiver position, velocity, clock offset and clock rate offset in a conventional navigation and control unit, and based on the unit that computes smoothed estimates for the next measurement interval.

Several antenna designs that utilize the NAVSTAR Global Positioning System in a low-cost system for general aviation aircraft were evaluated. Experimental investigations were made of crossed-dipoles, various types of crossed-slots, and microstrip antennas with modifications to improve their coverage. Principal plane radiation patterns for several of these antennas were measured on a one-seventh scale model of a Gates Lear Jet.

Henry Gray's classic anatomy textbook was first published in 1858 and has been in continuous publication ever since, revised and expanded through many successive editions. This recording is of the public-domain 1918 US edition (some information may be outdated). The illustrations can be found in the online text at bartleby.com. For the LibriVox recording, we have divided the book into five parts. Part 1 includes the Embryology and Osteology sections. (summary by Laurie Anne Walden)

Henry Gray's classic anatomy textbook was first published in 1858 and has been in continuous publication ever since, revised and expanded through many successive editions. This recording is of the public-domain 1918 US edition (some information may be outdated). For the Librivox recording, we have divided the book into five parts. Part 2 includes Syndesmology and Myology. The mathematical formulas (section 25) and the illustrations can be found in the online text at bartleby.com. (Summary by Laurie Anne Walden)

Henry Gray's classic anatomy textbook was first published in 1858 and has been in continuous publication ever since, revised and expanded through many successive editions. This recording is of the public-domain 1918 US edition (some information may be outdated). The illustrations can be found in the online text at bartleby.com. For the LibriVox recording, we have divided the book into five parts. Part 4 includes Neurology, the Organs of the Senses, and the Common Integument. (summary by Laurie Anne Walden)

Henry Gray's classic anatomy textbook was first published in 1858 and has been in continuous publication ever since, revised and expanded through many successive editions. This recording is of the public-domain 1918 US edition (some information may be outdated). The illustrations can be found in the online text at bartleby.com. For the LibriVox recording, we have divided the book into five parts. Part 3 includes Angiology, Arteries, Veins, and the Lymphatic System. (Summary by Laurie Anne Walden)

Henry Gray's classic anatomy textbook was first published in 1858 and has been in continuous publication ever since, revised and expanded through many successive editions. This recording is of the public-domain 1918 US edition (some information may be outdated). The illustrations can be found in the online text at bartleby.com. For the LibriVox recording, we have divided the book into five parts. Part 5 includes Splanchnology and Surface Anatomy and Markings. (Summary by Laurie Anne Walden)

6Nature's Miracles Volume 3: Electricity and Magnetism

By Elisha Gray

Elisha Gray (August 2, 1835 – January 21, 1901) was an American electrical engineer who co-founded the Western Electric Manufacturing Company. Gray is best known for his development of a telephone prototype in 1876 in Highland Park, Illinois and is considered by some writers to be the true inventor of the variable resistance telephone, despite losing out to Alexander Graham Bell for the telephone patent. <br><br>Nature's Miracles: Familiar Talks on Science, published in 1900, is a discussion of science and technology for the general public. (Summary from Wikipedia)

7Nature's Miracles Volume 1: World Building and Life

By Elisha Gray

Elisha Gray (August 2, 1835 – January 21, 1901) was an American electrical engineer who co-founded the Western Electric Manufacturing Company. Gray is best known for his development of a telephone prototype in 1876 in Highland Park, Illinois and is considered by some writers to be the true inventor of the variable resistance telephone, despite losing out to Alexander Graham Bell for the telephone patent. <br><br> Nature's Miracles: Familiar Talks on Science, published in 1900, is a discussion of science and technology for the general public. Volume I is subtitled World Building and Life: Earth, Air and Water. (Summary from Wikipedia)

Elisha Gray was an American electrical engineer who co-founded the Western Electric Manufacturing Company. Gray is best known for his development of a telephone prototype in 1876 in Highland Park, Illinois and is considered by some writers to be the true inventor of the variable resistance telephone, despite losing out to Alexander Graham Bell for the telephone patent.<br /><i>Nature's Miracles: Familiar Talks on Science</i>, published in 1900, is a discussion of science and technology for the general public. Volume II is subtitled <i>Energy and Vibration: Energy, Sound, Heat, Light, Explosives.</i> (Summary from Wikipedia)

9Little Tea Book

By Arthur Gray

<em>After all, tea is the drink! Domestically and socially it is the beverage of the world. There may be those who will come forward with their figures to prove that other fruits of the soil—agriculturally and commercially—are more important. Perhaps they are right when quoting statistics. But what other product can compare with tea in the high regard in which it has always been held by writers whose standing in literature, and recognized good taste in other walks, cannot be questioned?</em> (From the Preface)<br><br> A Little Tea Book is a clever book about all things tea- Eastern and Western tea history, stories, culture, quotes, and even poetry. A good little read for tea lovers everywhere. (Summary by Mary Kay)

10Elements of Botany

By Asa Gray

The book is intended to ground beginners in Structural Botany and the principles of vegetable life, mainly as concerns Flowering or Phanerogamous plants, with which botanical instruction should always begin; also to be a companion and interpreter to the Manuals and Floras by which the student threads his flowery way to a clear knowledge of the surrounding vegetable creation. Such a book, like a grammar, must needs abound in technical words, which thus arrayed may seem formidable; nevertheless, if rightly apprehended, this treatise should teach that the study of botany is not the learning of names and terms, but the acquisition of knowledge and ideas. No effort should be made to commit technical terms to memory. Any term used in describing a plant or explaining its structure can be looked up when it is wanted, and that should suffice. On the other hand, plans of structure, types, adaptations, and modifications, once understood, are not readily forgotten; and they give meaning and interest to the technical terms used in explaining them. - Summary by Asa Gray

Asa Gray was a highly-regarded botanist at Harvard University and a friend and collaborator of Charles Darwin. As a Christian, Gray was concerned with the disconnect developing through the nineteenth century between the growing understanding of the natural world and the traditional worldview assumed by orthodox Christianity. This book presents two lectures he gave to theology students at Yale College in which he argues that a disconnect is not inevitable, but that a Christian perspective can and should incorporate current understanding of the world provided by natural science. - Summary by BarryGanong

The Dial was an art magazine, which ran to five issues between 1889 and 1897. It was edited and published by Charles Ricketts and Charles Shannon from The Vale, their shared home in Chelsea, London. Contributors to this first number include the editors, R. Savage, and the poet John Gray (who is best known as the rumored inspiration for Oscar Wilde's fictional character, Dorian Gray). - Summary by Rob Marland

A collection of some of the most significant literary work on the English Lake District prior to Thomas West’s A guide to the Lakes (1778). The poet Thomas Gray takes the reader from Brough south to Kendal on his return from a tour in Scotland. An agricultural reformer, Arthur Young, also returning from Scotland, begins his journey in the northern parts of Cumberland with dry descriptions of local farming, but on arriving in Keswick, his account turns to the picturesque scenery around Derwent Water, Ullswater and Windermere. ‘Wild and romantic’ is Young’s phrase, yet the agriculturalist in him comes to the fore as he declares the enclosed landscapes around Kendal and Windermere to be the most picturesque of all. Thomas Pennant’s account of his journey through the district is cursory, and he seems not have noticed the lakes or mountains at all. West’s Guide quotes Gray, Young and Pennant, and its second edition included the full text of Gray’s unpublished letters as an addendum. It also included four short pieces. John Brown’s letter to his former pupil William Gilpin (who would become the foremost exponent of the ‘picturesque’) connects the scenery of the Lakes to European landscape painting. Experimental philosopher Adam Walker provides a note on a local curiosity, the underground passages of Dunald Mill Hole. John Dalton and Richard Cumberland were among the first in a long line of Lakeland poets to be inspired to verse.> - Summary by Phil Benson

14Silverpoints

By John Gray

Silverpoints is the first collection of poems by John Gray. Some saw Gray as a protégé of Oscar Wilde, who agreed to underwrite the publication of Silverpoints. It includes Gray's original poems and his translations from the French of Verlaine, Mallarmé, Rimbaud, and Baudelaire. - Summary by Rob Marland

15Confessions of Nat Turner, The Leader of the Late Insurrection in Southampton VA.

By Thomas R. Gray

This is a detailed description of the massacre that took place on August 21-23, 1831 that became known as Nat Turner's Rebellion. Nat Turner himself relates the events to the author from his jail cell in November of 1831 just days before he is hanged for his crimes. - Summary by Joel Kindrick

16Gentle Persuasion

By Alan Gray

Twelve stories from the author's life in Scotland, by Robert Cuthbert Johnstone, writing as Alan Gray. <br><br> For more information on the author see <a href="http://www.mhs.mb.ca/docs/people/johnstone_rc.shtml">his biography by the Manitoba Historical Society</a>.