摘要:

ABSTRACTChallenging areas for space station (SS) navigation include payload support, orbit prediction, traffic control, proximity operations, and automation. As the SS moves around the Earth in its orbit, the SS‐to‐sun line changes. The SS solar panels and radiators will be continually repositioned to maintain their desired orientation relative to the sun. The variation in the drag force due to changes in the SS cross‐sectional area will introduce difficulties in accurate prediction of the SS state vector necessary to support mission planning. Traffic control navigation will require relative navigation for more than 10 vehicles flying in formation around the SS. Maintaining relative state vectors for so many vehicles around the SS considering the “differential drag” effects between the SS and these vehicles will provide another challenge. As space shuttles or orbital maneuvering vehicles approach and dock with the SS, the guidance, navigation and control system must allow for precise attitude matching and extremely low contact velocity. New technology navigation sensors will be required to satisfy this navigation accuracy requirement. The largest challenge is determining the level of automation for these complex tasks so that human resources required for effective and safe operational management will be most effectively

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1985.tb00913.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

ABSTRACTPerformance results are presented for an autonomous navigator using refraction measurements of starlight passing through the upper atmosphere. To obtain a realistic performance indication, a full‐state simulation was developed comprising a truth model with an 8 × 8 gravity field, lunar and solar perturbations, atmospheric drag, real star distributions, and the effect of atmospheric density variations on the measurements. Some data on actual observations of refraction by the satellite HEAO‐2 are presented to show the variability in density within ± 20° latitude. The navigation portion of the simulation is capable of handling gravity fields up to degree 4 and order 4, and utilizes the extended Kalman filter to estimate satellite position and ve

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1985.tb00914.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

ABSTRACTThis paper documents a system description and operational concept for ensuring the integrity of the Global Positioning System (GPS) signals‐in‐space for use in the National Airspace System. The concept employs a ground monitoring network, L‐band transponders placed onboard already planned geostationary communication satellites to broadcast integrity data, and an integrated receiver containing both the GPS and the GPS Integrity Channel (GIC). The three, aforementioned system segments are described. The feasibility of employing a network of only four ground monitors to cover CONUS is analyzed. A discussion concerning implementation of such a system is also pres

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1985.tb00915.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

ABSTRACTDuring the period of January through April and also in August 1985, an engineering test team from the Transportation Systems Center (TSC) conducted a static and underway assessment of radionavigation systems in the Boston area. Sponsored by the Research and Special Programs Administration, the object of the tests was to gather data to determine the viability of the Global Positioning System, Standard Positioning Service (SPS), to provide navigation for terrestrial users. Concurrent data were also obtained on the LORAN‐C system to provide a current assessment of its capabilities.Four receivers, two GPS and two LORAN‐C, were used in the evaluation. Tests assessed the capabilities of receivers for conducting static survey and underway navigation. Test units were exposed to operating conditions representative of the rural, suburban and urban terrestrial environments. Parameters of interest included navigation accuracy (absolute and repeatable), interference susceptibility and signal availability. GPS results obtained with signals from the current constellation of satellites were compared with those expected from 18 and 21 satellite configurations. This paper presents a discussion of the conduct of the evaluation and a summary of the resu

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1985.tb00916.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

ABSTRACTIn this paper we show that the judicious use of all the information available from C/A code can provide results better than the reported accuracy of P code, with much lower cost. This performance, however, is limited to low‐dynamic, low‐jamming environments which are typical of civilian applications. The elegance of P‐code is primarily manifested in high dynamic vehicles (jets and missiles) and in jamming environments.Results are provided in stationary and low‐dynamic cases based on code‐phase, carrier‐phase, doppler, and integrated doppler measurements from TRIMBLE 4000 receivers. In particular, it is shown that the relative or differential accuracy of better than 10 centimeters can be achieved in low‐dynamic applications. Position fixes are obtained every second, after a short time of initial calibration and tracking.The improved accuracy is based on aiding the code‐phase measurements with integrated doppler. Each one second position fix, which is provided in both polar and Cartesian coordinates, is based on a complete and independent set of measured data, with no hypothetical modeling, interpolation, o

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1985.tb00917.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

ABSTRACTTwo kinematic surveys were performed, using TI‐4100s, which substantiate the author's earlier claim that centimeter‐accuracy relative surveys can be accomplished within seconds. The first test was carried out in Arkansas using wide‐bandwidth tracking. Although noisy, these data permitted the concepts and the data processing software to be verified. Based on results of this survey, a definitive kinematic survey experiment was designed and executed at the National Bureau of Standards, Gaithersburg, MD. The results of this experiment show that centimeter‐level relative surveys can be performed in seconds. A priori geodetic coordinates of the initial location of the “roving” antenna are not required since they, too, can be determined wit

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1985.tb00918.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1985.tb00919.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY