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1.
This paper briefly introduces the maneuverable feature of the slightly inclined geosynchronous orbit (SIGSO) satellites under
a new control model degraded from the geosynchronous orbit (GEO) communication satellites which will retire as most of the
fuel in these satellites has been consumed. Basing on the transmitting Chinese Area Positioning System (CAPS), the authors,
by analyses, indicate that such satellites can make an improvement to CAPS constellation configuration, especially to the
PDOP value from simulation. The results show that the use of SIGSO satellites can (1) actualize three-dimensional (3D) navigation
and positioning compared with the situation, which, only using GEO satellites, cannot be carried out, and improve navigation
and positioning accuracy to some extent; (2) reuse the communication services of these satellites for more years, and GEO
communication satellites will be retired at a later time and delay their time to become space debris and reduce their pollution
of the space environment, so that valuable space resources are maximally used. As for the use of these satellites in the transmitting
positioning system, the authors present some views and suggestions in this work.
Supported by the National Basic Research and Development Program of China (Grant No. 2007CB815501) and the Chinese National
Programs for High Technology Research and Development (Grant No. 2007AA12z343) 相似文献
2.
Selection of satellite constellation framework of CAPS 总被引:5,自引:5,他引:0
Based on the idea of transmitting the satellite navigation and positioning system, taking the distribution and variation of
the Position Dilution of Precision factor (PDOP), which is closely related with the precision of navigation and positioning,
within the China area as the primary criterion, we analyze and discuss the tentative plan of constellation configuration consisting
of geosynchronous orbit (GEO) communication satellites and inclined geosynchronous orbit (IGSO) satellites for the transmitting
Chinese Area Positioning System (CAPS). We emphatically consider the effect on the PDOP by the three major orbit parameters
including the inclination, eccentricity and right ascension of the ascending node (RAAN) of IGSO satellites, to research the
strategies of the constellation configuration of CAPS through software emulation. Various constellation configurations are
analyzed and compared and the results show that the constellation configuration, consisting of three IGSO communication satellites
in three orbits with the same inclination as 50°, the difference in RAAN as 120° and the same “8” shaped ground track centered
near 115°E and four or five GEO communication satellites within 60°E to 150°E, can satisfy the requirement that Chinese domain
is availably covered and the navigation and positioning with high precision could be obtained. Three relatively excellent
constellation configurations are initially suggested and some concerned issues are discussed in this work.
Supported by the National Basic Research and Development Program of China (Grant No. 2007CB815501) and the Chinese National
Programs for High Technology Research and Development (Grant No. 2007AA12z343) 相似文献
3.
It is a long dream to realize the communication and navigation functionality in a satellite system in the world. This paper
introduces how to establish the system, a positioning system based on communication satellites called Chinese Area Positioning
System (CAPS). Instead of the typical navigation satellites, the communication satellites are configured firstly to transfer
navigation signals from ground stations, and can be used to obtain service of the positioning, velocity and time, and to achieve
the function of navigation and positioning. Some key technique issues should be first solved; they include the accuracy position
determination and orbit prediction of the communication satellites, the measuring and calculation of transfer time of the
signals, the carrier frequency drift in communication satellite signal transfer, how to improve the geometrical configuration
of the constellation in the system, and the integration of navigation & communication. Several innovative methods are developed
to make the new system have full functions of navigation and communication. Based on the development of crucial techniques
and methods, the CAPS demonstration system has been designed and developed. Four communication satellites in the geosynchronous
orbit (GEO) located at 87.5°E, 110.5°E, 134°E, 142°E and barometric altimetry are used in the CAPS system. The GEO satellites
located at 134°E and 142°E are decommissioned GEO (DGEO) satellites. C-band is used as the navigation band. Dual frequency
at C1=4143.15 MHz and C2=3826.02 MHz as well as dual codes with standard code (CA code and precision code (P code)) are adopted. The ground segment
consists of five ground stations; the master station is in Lintong, Xi’an. The ground stations take a lot of responsibilities,
including monitor and management of the operation of all system components, determination of the satellite position and prediction
of the satellite orbit, accomplishment of the virtual atomic clock measurement, transmission and receiving navigation signals
to and from each satellite. In the north, the south, the east, the west and the center of Chinese main land, the function
of CAPS demonstration system is checked and measured. In cars and on board the system is also checked and measured. The results
are as follow: CA-code, horizontal positioning accuracy, 15–25 m (1 σ), vertical, 1–3 m; P-code, horizontal positioning accuracy,
8–10 m (1 σ), vertical, 1–3 m; velocity accuracy, CA-code, 0.13–0.30 m/s, P-code, 0.15–0.17 m/s; time accuracy, CA-code, 160
ns, P-code, 13 ns; determination accuracy of orbit ≤2 m. About 20 million US $ and two years are spent for the development
of demonstration. A complete CAPS system is now being established.
Supported by the National Natural Science Foundation of China (Grant No. 10453001), the National Basic Research Program of
China (Grant No. 2007CB815500), the National High Technology Research and Development Program of China (Grant No. 2004AA105030),
and the Funds of the Chinese Academy of Sciences for Key Topics in Innovation Engineering (Grant No. KGCXI-21) 相似文献
4.
A new method of ionospheric-free hybrid differential positioning based on a double-antenna CAPS receiver 总被引:1,自引:1,他引:0
Chinese Area Positioning System (CAPS) is a transmitted satellite navigation system moved by the Chinese Academy of Sciences.
Three basic modes of navigation and positioning with CAPS are given, and then a comparative analysis is made in this paper.
In terms of the principle that the ionospheric delay is at an inverse ratio to the frequency square, a new ionospheric-free
positioning method based on a double-antenna CAPS receiver is put forward. Then the hybrid differential observations and the
solving equations and algorithms for one epoch and multi epochs are deduced according to the basic principle of the method.
The method may remove the global errors in signal emission, propagation, transmission and receiving (e.g., ionospheric delay,
hardware delay, and clock error). So it is very convenient for the single-epoch solution and multi-epoch navigation and positioning,
and may efficiently improve the precision of real time CAPS navigation. Furthermore, the method can be used not only for the
geometric orbit determination of CAPS GEO and IGSO satellites and the navigation and positioning, but also for the estimation
of the tropospheric zenith delay, which is useful for the study of water vapor changes in the atmosphere. Polynomials are
used in this method to express the tropospheric zenith delay and CAPS satellite orbits within the limited time interval, which
reduces the number of unknown parameters and thus speeds the computation.
Supported by the Knowledge Innovation Project of the Chinese Academy of Sciences (Grant No. KGCX1-21), the National Basic
Research Program of China (Grant No. 2007CB815500), the National High Technology Research and Development Program of China
(Grant No. 2006AA12z303), the National Natural Science Foundation of China (Grant No. 40774009), and the Special Project of
Taishan Scholars of Shandong Province of China (Grant No. TSXZ0502) 相似文献
5.
Signal structure of the Chinese Area Positioning System 总被引:8,自引:8,他引:0
Proper signal structure is very important in the navigation, positioning, and time services of a satellite navigation system.
In this paper, the carrier wave characteristics, ranging code functions, BOC modulation, navigation data rate, the error-correcting
methods, and signal channel resource allocation are discussed in terms of the technical characteristics of the transforming
satellite navigation system and the resources of communication satellites. The results show that dual-frequency of C band
in the Chinese Area Positioning System (CAPS), compound ranging code, a combination of the coarse code and precise code, BOC
modulation, separate-channel transmission of different users are compatible with the satellite navigation system at present.
The experiments show that the current signal structure can meet the demand of CAPS.
Supported by the Major Knowledge Innovation Programs of the Chinese Academy of Sciences (Grant No. KGCX1-21), the National
High Technology Research and Development Program of China (Grant No. 2004AA105030), the National Natural Science Foundation
of China (Grant No. 10453001), and the Major State Basic Research Development Program of China (Grant No. 2007CB815502) 相似文献
6.
XuHai Yang ZhiGang Li ChuGang Feng Ji Guo HuLi Shi GuoXiang Ai FengLei Wu RongChuan Qiao 《中国科学G辑(英文版)》2009,52(3):333-338
A geostationary (GEO) satellite may serve as a navigation satellite, but there is a problem that maneuvers frequently occur
and the forces are difficult to model. Based on the technique of determining satellite orbits by transfer, a predicted orbit
with high accuracy may be achieved by the method of statistical orbit determination in case of no maneuver force. The predicted
orbit will soon be invalid after the maneuver starts, and it takes a long time to get a valid orbit after the maneuver ends.
In order to improve ephemeris usability, the method of rapid orbit forecasting after maneuvers is studied. First, GEO satellite
movement is analyzed in case of maneuvers based on the observation from the orbit measurement system by transfer. Then when
a GEO satellite is in the free status just after maneuvers, the short arc observation is used to forecast the orbit. It is
assumed that the common system bias and biases of each station are constant, which can be obtained from orbit determination
with long arc observations. In this way, only 6 orbit elements would be solved by the method of statistical orbit determination,
and the ephemeris with high accuracy may be soon obtained. Actual orbit forecasting with short arc observation for SINOSAT-1
satellite shows that, with the tracking network available, the precision of the predicted orbit (RMS of O-C) can reach about
5 m with 15 min arc observation, and about 3 m with 30 min arc observation.
Supported by the National High Technology Research and Development Program of China (Grant No. 2006AA12Z322), the National
Basic Research Program of China (Grant No. 2007CB815503), and the West Light Program of Chinese Academy of Sciences (Grant
No. 2007LH01) 相似文献
7.
The Chinese Area Positioning System (CAPS) is based on communication satellites with integrated capability, which is different
from the Global Positioning System (GPS), the International Maritime Satellite Organization (Inmarsat) and so on. CAPS works
at C-band, and its navigation information is not directly generated from the satellite, but from the master control station
on the ground and transmitted to users via the satellite. The slightly inclined geostationary-satellite orbit (SIGSO) satellites
are adopted in CAPS. All of these increase the difficulty in the design of the system and terminals. In this paper, the authors
study the CAPS configuration parameters of the navigation master control station, information transmission capability, and
the selection of the antenna aperture of the communication center station, as well as the impact of satellite parameters on
the whole communication system from the perspective of the transmission link budget. The conclusion of availability of the
CAPS navigation system is achieved. The results show that the CAPS inbound communication system forms a new low-data-rate
satellite communication system, which can accommodate mass communication terminals with the transmission rate of no more than
1 kbps for every terminal. The communication center station should be configured with a large-aperture antenna (about 10–15
m); spread spectrum communication technology should be used with the spreading gain as high as about 40 dB; reduction of the
satellite transponder gain attenuation is beneficial to improving the signal-to-noise ratio of the system, with the attenuation
value of 0 or 2 dB as the best choice. The fact that the CAPS navigation system has been checked and accepted by the experts
and the operation is stable till now clarifies the rationality of the analysis results. The fact that a variety of experiments
and applications of the satellite communication system designed according to the findings in this paper have been successfully
carried out confirms the correctness of the study results.
Supported by the National Basic Research and Development Program of China (Grant No. 2007CB815504) and the Technology Research
and Development Program of China (Grant No. 2007AA12z343) 相似文献
8.
This work aims to obtain a wide area differential method for geostationary orbit (GEO) constellation. A comparison between
the dilution of precision (DOP) of four-dimensional (4D) calculation including satellite clock errors and ephemeris errors
and that of three-dimensional (3D) calculation only including ephemeris errors with the inverse positioning theory of GPS
shows the conclusion that all the 3D PDOPs are greatly reduced. Based on this, a basic idea of correcting satellite clock
errors and ephemeris errors apart is put forward, and moreover, a specific method of separation is proposed. Satellite clock
errors are separated in a master station with time synchronization, and all the remaining pseudo-range errors after the satellite
clock errors have been deducted are used to work out ephemeris corrections of all GEO satellites. By a comparative analysis
of user positioning accuracy before and after differential, the wide area differential method is verified to be quite valid
for GEO constellation.
Supported by the National Natural Science Foundation of China (Grant No. 10778715), the National Key Basic Research Development
Program of China (Grant No. 2007CB815502), and the Scientific Research Fund of Hunan Provincial Education Department (Grant
No. 08B039) 相似文献
9.
Satellite atomic clocks are the basis of GPS for the control of time and frequency of navigation signals. In the Chinese Area
Positioning System (CAPS), a satellite navigation system without the satellite atomic clocks onboard is successfully developed.
Thus, the method of time synchronization based on satellite atomic clocks in GPS is not suitable. Satellite virtual atomic
clocks are used to implement satellite navigation. With the satellite virtual atomic clocks, the time at which the signals
are transmitted from the ground can be delayed into the time that the signals are transmitted from the satellites and the
pseudorange measuring can be fulfilled as in GPS. Satellite virtual atomic clocks can implement the navigation, make a pseudorange
difference, remove the ephemeris error, and improve the accuracy of navigation positioning. They not only provide a navigation
system without satellite clocks, but also a navigation system with pseudorange difference.
Supported by the National Basic Research Program of China (Grant No. 2007CB815502) and the National High Technology Research
and Development Program of China (Grant No. 2007AA12Z300) 相似文献
10.
GuoXiang Ai PeiXuan Sheng JinLin Du YongGuang Zheng XianDe Cai HaiTao Wu YongHui Hu Yu Hua XiaoHui Li 《中国科学G辑(英文版)》2009,52(3):376-383
This work describes the barometric altimetry as virtual constellation applied to the Chinese Area Positioning System (CAPS),
which uses the transponders of communication satellites to transfer navigation messages to users. Barometric altimetry depends
on the relationship of air pressure varying with altitude in the Earth’s atmosphere. Once the air pressure at a location is
measured the site altitude can be found. This method is able to enhance and improve the availability of three-dimensional
positioning. The difficulty is that the relation between barometric pressure and altitude is variable in different areas and
under various weather conditions. Hence, in order to obtain higher accuracy, we need to acquire the real-time air pressure
corresponding to an altimetric region’s reference height. On the other hand, the altimetry method will be applied to satellite
navigation system, but the greatest difficulty lies in how to get the real-time air pressure value at the reference height
in the broad areas overlaid by satellite navigation. We propose an innovational method to solve this problem. It is to collect
the real-time air pressures and temperatures of the 1860 known-altitude weather observatories over China and around via satellite
communication and to carry out time extrapolation forecast uniformly. To reduce data quantity, we first partition the data
and encode them and then broadcast these information via navigation message to CAPS users’ receivers. Upon the interpolations
being done in receivers, the reference air pressure and temperature at the receiver’s nearby place is derived. Lastly, combing
with the receiver-observed real air pressure and temperature, the site’s altitude can be determined. The work is presented
in the following aspects: the calculation principle, formulae, data collection, encoding, prediction, interpolation method,
navigation message transmission together with errors causes and analyses. The advantages and shortcomings of the technique
are discussed at the end.
Supported by the National Basic Research Program of China (Grant No. 2007CB815500), the National High Technology Research
and Development Program (Grant No. 2004AA105030), the Pilot Project of the Knowledge Innovation Program of the Chinese Academy
of Sciences (Grant No. KGCX1-21), and the National Natural Science Foundation of China (Grant No. 10453001) 相似文献