摘要:

ABSTRACTIn 1928, the city of Detroit had the distinction of being the first city in the world to introduce police radios and two‐way radio police dispatch. Sixty years later, another world first by the City of Detroit Police Department was announced by Mayor Coleman Young: the introduction of emergency vehicle tracking integrated with the “Enhanced 911” emergency dispatch system. This system is the most ambitious undertaking of its kind and incorporates many innovative features, including automatic tracking of the largest fleet of Loran‐C equipped vehicles. A complete floor of the Detroit Police Headquarters has been renovated to provide the most advanced facility for public safety dispatch. This paper presents concepts and some details of the Automatic Vehicle Location System developed to complete the elements of the Detroit Public Safety Dispatch

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1989.tb01513.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTThis paper considers some of the features that contribute to the military survivability of GPS in times of crisis. It discusses each segment in turn, and addresses the potential threats and the applicable countermeasures that can enable GPS to provide continuing service. The design aspects protect primarily military applications, but the benefits apply equally to the civil community.

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1989.tb01514.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTThe country's space systems ground command and control network is rapidly becoming antiquated, and will not be able to handle the expansion of space traffic projected for the twenty‐first century. There is a heavy reliance on vulnerable overseas ground locations that are not guaranteed. A cooperative satellite system architecture based on GPS would significantly alleviate the complexity of a future command and control structure. Specifically, if each satellite were to carry a GPS receiver as part of its telemetry, tracking, and command subsystem, all space vehicles could maintain accurate and reliable time, ephemeris, and pointing estimates. This satellite navigation and status data could then be transmitted on a regularly scheduled basis to a ground monitoring station or a Tracking and Data‐Relay Satellite System (TDRSS) Satellite. In this way, normal operations would be reduced to merely reviewing the telemetered data. In case of anomalies in the data or a space emergency, a dwell mode would be initiated in which the ground segment would begin active tracking of the space vehicle. This paper outlines the structure of such a GPS‐based cooperative satellite monitoring s

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1989.tb01515.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTThe future navigation accuracy requirement for nonprecision approaches has been estimated to be 100 m. GPS can satisfy this requirement by limiting the 95 percent horizontal position determination accuracy for civil users to 100 m. The FAA is investigating GPS signal integrity monitoring and the associated monitor alarm limits in order to satisfy the integrity response time requirements for non‐precision approaches. This paper documents a rationale for the 100 m GPS horizontal accuracy requirement and evaluates the impact of using GPS monitor alarm limits greater than 100 m. The GPS monitor alarm limit must be set above 100 m in order to reduce the number of potential alarms. The significant impact on nonprecision approaches, as defined in the Terminal Instrument Procedures, appears to be the size of the obstacle clearance areas and their effect on the minimum descent altitud

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1989.tb01516.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTThe Radio Technical Commission for Maritime Services (RTCM) Special Committee (SC)‐104 on Differential GPS has established a standard data format for providing differential GPS services. The satellite pseudorange corrections that are broadcast in the RTCM SC‐104 differential GPS navigation message lump together the errors from a number of different sources. This results in a degradation of the differential navigation accuracy if the user is operating at a distance from the differential reference station. Generally, the user must be within 100 nmi of the reference station to benefit fully from the differential GPS corrections.This paper presents an Extended Differential GPS concept that extends the range of operation of the differential GPS message. By using a network of differential GPS stations, one can compute a differential GPS message that provides corrections for the different components of the pseudorange error. This allows the differential GPS navigation accuracy to be extended to a range of 1000 nmi from the master differential stat

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1989.tb01517.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTThis paper summarizes the results of a series of direct measurements conducted to characterize the GPS signal environment in land vehicular operations for a variety of highway, city, and railroad situations. The basic instrumentation for these observations consisted of a NAVCORE I (TM) GPS receiver configured to output key measurements to a microcomputer as a data recording device. The results of these tests are presented in tables of the percentages of distance traveled in which one or more and two or more satellite outages were encountered, and in histograms of the outage probabilities as functions of the distance durations of the outages.The equipment was installed both in a van‐type vehicle for highway and city street tests, and in a “Hy‐Rail” vehicle for operation on railroad

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1989.tb01518.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTWander azimuth frames are one of the most popular reference frames used in inertial navigation systems today. Perhaps the only difficulty with these frames is that they are so hard to visualize. This paper presents a simple, closed‐form geometric representation of wander azimuth frames along all small and great circles for a spherical earth model. An experiment with globe and paper makes wander azimuth frames understandable on an intuitive, visual leve

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1989.tb01519.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1989.tb01520.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1989.tb01521.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY