摘要:

ABSTRACTThe Navstar/Global Positioning System is now in Phase II, the Full Scale Engineering Development phase, which will extend into 1983. For the next few years, before the buildup to an operational 18‐satellite constellation, four, five, or, possibly, six satellites will be maintained in orbit to support a variety of Phase II activities.This paper discusses the worldwide coverage that is provided by the Phase II constellation. Even with this limited number of satellites, much of the earth is afforded some coverage, though the period of coverage will vary from location to location. Certain locations are favored whereas others are not. A primary consideration in the design of this partial constellation was the need for engineering development tests of Navstar user equipment at the Army Proving Grounds in Yuma, Arizona. Four satellites provide 2 hr of three‐dimensional navigation test time at this location once each day. Because the satellites assume the same relationship to each other four times each day, three other areas of the earth will be provided coverage similar to that at Yuma. Six hours after the test period at Yuma, a similar coverage pattern appears over the South Atlantic, then over the Middle East, and, finally, over New South Wales in Australia.Even at some distance from these favored locations, good coverage is provided (and has been exploited), although generally for a shorter period of time. Navstar has been successfully used as a range instrumentation system by the Navy in Atlantic Ocean tests designed to improve the accuracy of the Trident missile. During the Fall of 1980, there was a series of tests in Europe, also quite successful. Just as there are four most‐favored areas on the earth, there are also four areas for which the coverage is poor. These four are over ocean areas and include the Canary Islands in the North Atlantic, the Mascarene Islands off Madagascar in the Indian Ocean, Wake Island in the North Pacific, and Easter Island in the South Pacific.This paper presents an overview of worldwide coverage, showing the variation between many locations on the earth. With only four or five satellites in the current development phase, Navstar is a part‐time system that provides potential users a few hours of service each day. This could be useful for those users who are able to adjust their operations to when the satellites are visible or who wish to gain experience with Navstar prior to the buildup to the operational satellite conste

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1981.tb00764.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTThis paper describes all‐digital baseband correlation processing of GPS signals. The features of this highly digital mechanization are its (1) potential for improved anti‐jamming (AJ) performance, (2) fast acquisition by a digital matched filter, (3) reduction of adjustment, (4) increased system reliability, and (5) provision of a basis for realization of the high degree of very large‐scale integration (VLSI) potential for development of small economical GPS sets.Described are an experimental GPS receiver/digital processing system that has been operating for two years, and an improved engineering development model that is now in test. The basic technical approach consists of a broadband, fix‐tuned RF converter followed by a digitizer, digital‐matched‐filter acquisition section; phase‐and delay‐lock tracking via baseband digital correlation; software acquisition logic and loop filter implementation; and all‐digital implementation of the feedback numerically controlled oscillators (NCOs) and code generator. Baseband in‐phase (I) and quadrature (Q) tracking is performed by an arctangent angle detector followed by a phase‐unwrapping algorithm that eliminates false locks induced by sampling and data bit transitions, and yields a wide pull‐in frequency range approaching one‐fourth of the loop iteration frequency.Test data from the experimental unit includes basic resolution and computation noise of the digital processing, pseudorange and range‐rate errors, and acquisition times for

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1981.tb00765.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTThe air carrier avionics arena is witnessing some interesting evolutionary developments in flight guidance. Among these are the strapdown attitude and heading reference system, the ring laser gyro inertial navigator and the Omega/VLF navigator. Passive navigation systems are now available which emulate VOR/DME. However, there is another development on the horizon which could be revolutionary. It is the Global Positioning System, which has the potential to overtake many of the developments now becoming available. This paper addresses the design and capability of an integrated GPS/strapdown AHRS as a replacement for the pure inertial navigator and other sensors now widely used by the air carriers.This integrated system simultaneously exhibits the excellent verticality of a dynamically erected AHRS and the outstanding position and velocity accuracy of the satellite navigator. The splendid velocity accuracy of GPS, even with the C/A code and controlled position accuracy, provides the key link to the potential of the integrated system. The system does not require external air speed or heading but can use encoded barometric altitude. As an output the system can provide a comprehensive slate of vehicle data for the flight management, flight control and flight instrument systems. This single system will outperform the pure inertial navigator at substantially less acquisition and maintenance cost. The potential for global and continuous position is not available at any price. The system can also be fitted with the same kind of VOR/DME emulation now appearing in other passive navigators. Unprecedented capability and economy in air carrier operations are in the offing in this new generation of flight guidance avionics.

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1981.tb00766.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTIn the four decades since the first microwave radar with a plan‐position‐indicator was installed inU.S.S. Semmesin the spring of 1941, marine radar has been praised as boon to reduced visibility navigation, cursed with the phrase “radar‐assisted‐collisions”, and now required for installation on most seagoing vessels. This paper presents a personalized perspective of how radar has been used by mariners since the first radars started appearing in quantity in the U.S. and British fleets in 1942. In World War II, at night when all ships were darkened, radar was the military vessel's primary sensor for detection of surface targets, station keeping information, for intercepting targets, for keeping merchant ship convoys in formation and for entering and leaving port in poor visibility. A generation of watch officers developed competence in the use of marine radar. After the war, merchant ships were equipped with radar with mixed results. A new generation of watch standers had to learn to use radar from experience. The development over the years of what is required to effectively use radar to maneuver and navigate a ship is explored. Examples of the use of radar for navigation and maneuvering are described. Development of computer based aids is briefl

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1981.tb00767.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTThe FAA received a NAVSTAR GPS Z‐set for independent test and evaluation after this receiver was acceptance‐tested aboard a United States Air Force C‐141 aircraft over the Yuma Proving Ground instrumented range. This paper describes the initial familiarization studies conducted by the FAA in a twin turboprop engine Grumman Gulfstream, with the Z‐set in a stand‐alone configuration. The familiarization studies included satellite shielding tests, satellite acquisition/reacquisition tests, non‐precision approaches to five East Coast airports, and operations in high noise/RFI environments (over airports, cities, and

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1981.tb00768.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTThis paper describes a flight test program and the resultant navigation performance achieved on an Advanced Development Model (ADM) Ring Laser Gyro Navigator (RLGN) in a Navy A‐7E and P‐3C aircraft. The RLGN system was developed by the Naval Air Development Center (NAVAIRDEVCEN) under the Advanced Technology Demonstration (ATD) Laser Gyro Program. Initiated in 1976 by the Naval Air Systems Command, the objective of this program is to demonstrate the military utility of laser gyros for aircraft navigation.As the RLGN represents a significant departure from conventional gimballed inertial system technology, a brief functional system description is given highlighting key hardware and software design features. This is followed by a description of the A‐7E flight test program, its objective, flight profiles, method of data acquisition and analysis of results.The P‐3C flight test program is discussed including a description of the flight test recording instrumentation, flight profiles, data reduction, and analysis of results. An indication of system reliability, maintenance, and calibration actions versus system design goals is given. Effects of high latitude on system alignment and navigation performance are also high

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1981.tb00769.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTThis paper describes a system for real‐time tracking of long‐range missiles based on use of the Global Positioning System (GPS). When GPS is fully operational, an in‐place reference system will exist for use in tracking moving vehicles such a missiles, aircraft, and ground vehicles. In order to obtain the maximum benefit of this capability, an economical means of tracking the test vehicles is necessary. This is particularly true in tracking expendable test vehicles such as missiles.The techniques presented in this paper represent an approach to economical tracking of expendable test missiles. In this concept, the tracked missile receives the GPS signals, translates a composite signal spectrum to a new S‐band frequency, and then transmits the composite S‐band spectrum to a ground‐station receiver. The ground station receives and processes the translated GPS signals into normal pseudorange and range‐rate measurements of the missile. A Kalman filter is used to obtain a position and velocity solution. In addition to its capability for standalone performance, the described system could be incorporated into existing tracking systems, resulting in improved trac

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1981.tb00770.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTThe author will describe the Federal Radionavigation Plan which delineates policies and plans for Government‐provided radionavigation services. The plan gives respective areas of authority and responsibility and provides a management structure by which the operating agencies will define requirements and meet them in a cost‐effective manner. It replaces the DOT National Plan for Navigation, and those sections of the DOD Joint Chiefs of Staff (JCS) Master Navigation Plan dealing with common‐user systems.The Plan covers Federally‐operated systems having a high degree of common use (either military/civil or between the various transportation modes). The systems considered are: LORAN‐A; LORAN‐C; OMEGA; VOR; VOR/DME; VORTAC; TACAN; ILS; TRANSIT; RADIOBEACONS; MLS; and NAVSTAR GPS. The goal is to select a suitable mix of these systems which can meet diverse user requirements for accuracy, reliability, coverage, operational utility, and cost; provide adequate capability for future growth; and minimize duplication of services. However, selection of an optimum mix to satisfy the users, while holding the number of systems and government and user costs to a minimum, involves complex operational, technical, institutional, international and economic trade offs. This Plan establishes a methodology for DOT and DOD to address these questions and arrived at an initial, optimum mix determination in t

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1981.tb00771.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTFew concepts in today's maritime world can so quickly lead to argument as those gathered together under the heading of VTS. Some of this, at least, arises because the community has failed fully to grasp what VTS is. Control of marine traffic is here assumed to equate with marine traffic management—space management—effected through a VTS. Traffic management has both passive and active aspects, and to be effective requires adequate enforcement machinery. VTS is essentially a political creature, intended by the public to help insure politically adequate safety. Basic VTS functions are distributed between the VTC and the ship, with the VTC of necessity having plenary authorityin emergencies, even over a ship underway. In the end, here, it is the Coast Guard the public holds responsible. VTS is today commencing to reach offshore, in the form of regional OVTM. Information integration/communications remain a problem. An internationally agreed outline VTS code would be most useful. There is no need for all this trouble over

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1981.tb00772.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Book reviewed in this article:For the MarinerNAVIGATION AFLOAT, Alton B MoodyHigh AdventuresWINGED HOURS, Frank GriffithTHE VOYAGE OF TORRES, Brett Hilder

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1981.tb00773.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY