摘要:

AbstractThe emergence of satellite navigation has brought about the need for compact representations of satellite ephemerides. Polynomial representations offer several advantages. Polynomial representations of navigational and astronomical ephemerides are usually derived from discrete least squares approximations. However, to ensure a uniform distribution of the error, one should aim at a continuous Chebyshev approximation, whereby the maximum error in absolute value taken over the entire interval is minimized. This is feasible when the ephemeris is generated from a literal (analytical or semi‐analytical) development. But a discrete Chebyshev approximation, whereby the maximum error in absolute value is considered only over a finite set of reference points in the interval, is a realistic compromise. Application to the moon and geosynchronous satellites has given good results. On the whole, long ranges (several times the sidereal period) may be covered by polynomials of degree 30 to 50 with a moderate error. A low degree approximation over half the period usually delivers a high accuracy. Gibbs' phenomena, i.e. rapid oscillations of increasing amplitudes in the error curve at both ends of the approximation interval are of course absent, contrary to what happens usually in a least squares approximatio

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1979.tb01350.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractThe navstar global positioning system (GPS) is currently in the Concept Validation phase of development. A variety of Navstar user equipment is being tested aboard test vehicles provided by the three military services. Testing has recently been conducted at the Yuma Proving Ground and, at sea, in local San Diego waters, using up to four Navstar satellites. This paper presents some of the more significant results of that testing.

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1979.tb01351.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1979.tb01352.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractTechniques to enhance combat power in the face of increasing threat capabilities are of continuing interest to U.S. commanders. One such technique with the potential for high combat power pay‐off evolves from the application of electronic technology to the functions of position determination and battlefield navigatio

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1979.tb01353.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractSince the release of the Navy Navigation Satellite System (or Transit) to the public in 1967, the oil and gas exploration industry has been an active innovator and end user of this potentially highly effective navigation and positioning tool. However, many knowledgeable people outside the oil exploration community, and even some people from within the community, do not know the role played by Transit in the pursuit of increasingly difficult to find oil and gas reserves. Moreover, these same individuals are unaware of the costly operational delays in exploration activity caused by the present poor orbital coverage in the Transit System.This paper attempts to call attention to the oil and gas exploration communities' requirements for navigation and positioning and to the active role played by the Transit Satellite System. The possible uses of future navigation satellite systems (such as GPS) are also explored.Most important, this paper puts forth the plight of the civil user of the present day Transit system and the civil user's similar predicament if commercial use of GPS is available only in the coarse code mode.

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1979.tb01354.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractUntil recently, space programs such as Viking used the “block redundancy” concept for spacecraft navigation/control, whereby multiple navigation units of the same configuration were packaged in different locations on the spacecraft. The desire for a more efficient and cost effective approach to redundant spacecraft navigation systems prompted NASA to fund the development of a redundant Inertial Reference Unit (DRIRU I) based on the utilization of three dry, tuned‐gimbal, two‐degree‐of‐freedom gyroscopes. Each gyroscope, together with its associated electronics and power supply, comprises a “gyro channel” which provides two axes of angular rate information and is totally independent from the other two gyro channels. The first of these systems was successfully flown on the Voyager Program.More demanding space programs of the late 1970's and through the 1980's, such as SOLAR MAX, LANDSAT, ASPS, and SPACE TELESCOPE, have prompted the further development of a standardized high accuracy IRU (DRIRU II) based on the same design concepts and objectives stated above.This paper provides a comprehensive discussion of the system design configuration, performance capability, and environmental capability of the NASA Standard Redundant Dry Rotor Inertial Reference Unit (DRIRU II). Further, the design flexibility of the DRIRU II is discussed to allow potential users to consider adaptation of the unit to their unique space progr

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1979.tb01355.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractA method of determining an observer's terrestrial latitude and longitude is proposed which, once the altitude observations are made and corrected to true altitudes, can be performed entirely on a mini‐compute

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1979.tb01356.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

AbstractWorld‐wide precise time dissemination by use of the Transit satellite system has been available since the system became operational. Recent introduction of a receiver designed expressly for time recovery from Transit has drawn new attention to this important resource. This paper discusses the performance of Transit as a time distribution system and some immediate and future application

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1979.tb01357.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1979.tb01358.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1979.tb01359.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY