摘要:

ABSTRACTGPS will offer extremely high navigation performance and has a promising future for most civil navigation needs. However, certain users consider that it may have insufficient integrity and limited availability. This paper describes a method for determining the availability of three different GPS services (positioning, supplemental navigation, and sole means navigation) when users also operate complementary equipment. The method is relevant to several different scenarios: two‐dimensional or three‐dimensional applications; different navigation phases in which GPS is being used and induced positioning accuracy requirements; and various GPS constellations, possibly supplemented by geostationary satellites. It will be shown that GPS availability is highly sensitive to all these parameters. The application discussed is the nonprecision approach phase in civil aviation, where a 21‐satellite and a 24‐satellite constellation are considered. The results are then extended to other flight phases and maritime users. Part II of this paper, containing state‐probability analyses of 21‐ and 24‐satellite constallations, will be published in the Fall 1990 issue of this journal. The results of Part II are a major in

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1990.tb01542.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTBoth the U.S. and the Soviet Union have been developing global satellite navigation systems that are scheduled to become operational early in this decade. With warming relations between the two superpowers, the possibility of cooperation in the civilian use of the two global navigation systems is quite good. This paper discusses the advantages of an integrated GPS/GLONASS receiver for various applications. Observations of the operational status of GLONASS are reported. Some comparisons are drawn between GPS and GLONASS. Coverage information is given on the two systems which shows some of the advantages of an integrated receiver. Finally, a description is given of a testbed receiver that was developed to perform navigation, surveying, and time transfer experiments using satellite signals from both systems.

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1990.tb01543.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTAn algorithm for processing strapdown inertial data in an earth‐fixed Cartesian frame is developed in this paper. It is compared with the standard algorithm that uses the local‐level frame and the geographic coordinate system for the model formulation. A general formulation of the modeling equations for the two approaches is given, and the linearization of the equations and the formulation of the appropriate Kalman filter are outlined. The derivation of the reference gravity model for both frames is briefly discussed, and numerically efficient formulas for the model's computation are given. In the case of the Cartesian algorithm, this leads to new formulas for all three components of the gravity vector. Real data are used to compare the two algorithms and to show that the accuracy is the same in both cases, but that the Cartesian formulation is about 30 percent more effici

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1990.tb01544.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTThe current solar cycle, which began in September 1986, may prove to be the highest ever, as measured by sunspot numbers and radio flux. The cycle's frequent and strong solar flare activity can be illustrated by the March 1989 episode, which caused many problems for navigation systems. Flares and the geomagnetic storms that sometimes accompany them can disrupt low‐frequency systems such as Loran‐C, as well as the satellite‐borne GPS. Although the maximum of the solar cycle is expected during the first quarter of 1990, flare activity is likely to persist at high levels for a few years to follow. Geomagnetic activity may occur at any time in the cycle, and thus geomagnetic disruptions are possible at any point in the

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1990.tb01545.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTThe notion of aiding GPS code‐ranging information with carrier phase measurements has been around for quite some time. The integration of these two complementary forms of data can provide highly precise position solutions corrupted by very little high‐frequency error, which is advantageous particularly for high‐dynamical situations. This paper presents two schemes, based on the Kalman filter, for integrating GPS code and carrier measurements efficiently. One of these schemes involves a general combination of the two types of measurements, where the vehicle motion is described as a random process. In the other, the continuous carrier phase measurements provide a dynamically exact reference trajectory in much the same manner as in an inertial system, and the pseudorange data is then used to update this reference trajectory via a Kalman filter. This method of integration looks especially attractive as a means of achieving good dynamical response while still retaining the benefits of filtering the pseudorange

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1990.tb01546.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

ABSTRACTThe primary use of Omega signals is to extract phase information as a means of fixing an observer's position. This paper considers the feasibility and potential applications of extracting directional information from Omega or other VLF signals. This directional information could be used as input to a gyro‐magnetic compass as an alternative to the magnetic input. It could also be used to assist the tracking and thus improve the position fixing capability of the Omega receiver itsel

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1990.tb01547.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1990.tb01548.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1990.tb01549.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1990.tb01550.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1990.tb01541.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY