The new generation of space datum in China should comply with the latest IERS (International Earth Rotation and
Reference System Service) convention as much as possible. This paper has deeply addressed and researched the main
improvements of the current version IERS Conventions (2003), including the changes of the Terrestrial Reference
System, the Celestial Reference System, and the transformation between them, the tide correction and so on, which
would undoubtedly benefit the realization and maintenance of our space datum. Based on PANDA (Position And
Navigation Data Analyst) software developed by GNSS Center of Wuhan University, we analyzed the effect of
improvements of the IERS Conventions (2003) on precise orbit determination and precise positioning. The results show
that the effect of improvements of models of the coordinate transformation between the celestial and the terrestrial
reference system and tide correction (including solid earth tide, ocean tide and polar tide) on precise orbit determination
are 4mm, 9mm and 5mm in terms of RMS in along, cross and radial direction of the track; and the effect of the
improvement of the tide models on positioning is basically under 0.6mm, and the RMS of the differences are 0.3mm,
0.3mm and 0.2mm in X, Y and Z.
Space Very Long Baseline Interferometry (SVLBI) is the unique space technique that can
directly interconnect the main three reference systems for geodesy and geodynamics. However, the
estimable sequence of geodetic parameters including nutation parameters within SVLBI mathematical
model has not been determined yet. In this paper, using the mathematical model of space-ground SVLBI
observations including the nutation parameters derived by WEI Erhu et al.(2008), the estimable
parameter sequence is determined. And the same study is done with space-space SVLBI Observations.
To study the standard deviation of nutation parameters estimated with space-ground SVLBI observations,
the model of variance propagation is derived, with which some numerical tests are done. Finally, the
results are present.
The high precision relative positioning is one of the key conditions of multiple earth-observation satellites
differential observation. Usually, the earth-observation satellites' relative positions are got by GNSS differential
positioning. The key technology of GNSS high precision differential positioning is carrier phase AR (Ambiguity
Resolution). The distance between two earth-observation satellites is from several kilometers to several hundreds
kilometers. So it's a problem of ambiguities resolution for mid-long distance baseline. There are a lot of difficulties to
solve this kind of ambiguities such as large double difference systematic errors. In order to solve these difficulties, this
paper proposed a fast and kinematic AR method named as CPES (Coordinate Parameters Eliminated and Stepwise)
method which is based on LAMBDA method. At first, the primary theories of this method are introduced. Then, the steps
from wide-lane ambiguities resolution to L1, L2 ambiguities resolution are proposed. Lastly, several examples' results
show that this AR method has the advantages of fast speed and high reliability.
Under the financial support of several Chinese national scientific projects, PANDA (Positioning And Navigation Data
Analyst) software developed originally by Wuhan University has achieved the advanced level in the world. PANDA is
currently recognized as a main research tool in several famous institutes in the GNSS community. In this paper, the
recent development of PANDA software is introduced, including the COSMIC orbit determination in low Earth orbits,
the real-time GPS satellite orbit and clock determination and precise point positioning with ambiguity resolution. It is
concluded that PANDA is of great improvement in the past five years, and more advancement will be made in its
pragmatic aspect especially in engineering applications.
KEYWORDS: Satellites, Solar radiation models, Kinematics, Satellite navigation systems, Automatic control, Solar radiation, Data modeling, Data processing, Data analysis, Statistical modeling
Periodical orbit maneuver makes a serious problem for navigation users to get correct Geostationary
(GEO) orbit information in real-time. As a result, it is very difficult to use GEO satellite for navigation
application purpose. In this presentation, the precision of the orbit determination of GEO satellite
without maneuver operation has been introduced at first. Then, two strategies of orbit determination
during satellite maneuvers are discussed in details. One method is called as maneuver force modeling;
the other is empiric force parameter estimation. The results show the residual is of the order of 40 cm
by using these strategies, and the position difference between dynamic orbit and kinematics orbit is
about 10 m.
The paper puts forward a new method of real-time precise GPS satellite clock offset estimation. The method adapts
the Square Root Information Filter (SRIF) that has benefits of the numerical stabilization, also eliminates the ambiguity
parameter through the difference of the epoch which will save the time of the filter consumedly. Based on the above
methods, the real-time precise clock offset estimation module is added to the PANDA software which developed by the
WuHan University for Position and Navigation Data Analysis. In addition, a examples are analyzed for one week
observation from 70 IGS global tracking stations around the world with the software, The results show: The software can
achieve the 1HZ's updating clock offset resolution for a global network of GPS tracking stations. Also, the accuracy of
0.2ns is achieved with the software compared with the IGS final products.
Real-time high-precision GPS positioning and navigation requires that cycle-slip in the undifferenced carrier-phase
measurements can be detected instantaneously. A slip of only a few cycles can bias measurements enough to make
centimeter-level positioning or navigation difficult. Over the past decade a number of methods have been developed to
detect and repair cycle slips. The majority of methods invariably are used in the post-processing cycle-slip detection. A
method has been developed from various exiting techniques, that provides real-time cycle-slip detection (i.e., using only
current epoch's GPS carrier-phase measurements). The approach utilizes two linear combinations, the Geometry-free and
the Melbourne-Wübbena combination. The low degree polynomial fitting and running-average filter are used to detect
cycle slips. Simulation tests are conducted to the kinematic data. Results indicate that single-cycle slips can be reliably
detected instantaneously.
KEYWORDS: Error analysis, Global Positioning System, Phase modulation, Statistical analysis, Geodesy, Data centers, Data modeling, Network security, Aluminum, Analytical research
One goal of the IERS to define and maintain the ITRF is to combine all major space geodetic techniques (GPS, VLBI, SLR, LLR and DORIS solution in the SINEX format) into an integrated consistent set of high-accuracy products. In such a combination, estimating and removing the systematic errors between different SINEX files is an important issue. For this purpose software GNAS (Geodesy Network Analysis System) is developed, which is able to estimate 7 Helmert transformation parameters of station coordinates within the process of combination. Besides, the GNAS software enables us to combine EOPs and station coordinates not only separately, but also simultaneously. We discuss the advantages and disadvantages when systematic parameters are estimated for each Analysis Center (AC) or for each SINEX file. One can estimate either the whole 7 Helmert parameters or only a set of them (e.g. without 3 rotation parameters). Different procedures have different effects on the combined solutions, especially when EOPs and station coordinates are combined simultaneously. Detailed discussions, numerical examples and some results analysis are given in this paper.
KEYWORDS: Satellites, Data modeling, Global Positioning System, Satellite navigation systems, Solar radiation models, Software development, Data analysis, Navigation systems, Atmospheric modeling, Data processing
Firstly, the PANDA (Position And Navigation Data Analysis) software, developed by Wuhan University, is introduced in this paper. And then we present a new method for the precise orbit determination (POD) and near real-time orbit prediction using the regional tracking network by the PANDA software. The orbit determination results are compared with final precise orbit provided by IGS and the accuracies are given detailedly. The results should encourage the realization of regional high precision orbit determination services.
KEYWORDS: Global Positioning System, Data centers, Data modeling, Phase modulation, Satellite navigation systems, Data analysis, Statistical analysis, Field emission displays, Geodesy, Data processing
The GTRF initial realization and long-term maintenance follows the state of the art of TRF implementation. In this paper, the background of GTRF realization and the history of ITRF establishment were reviewed firstly. The precious experience gained from IERS activities is very helpful in GTRF realization, based on such situation, so the combined model and strategy for simulating GTRF initial realization by GPS data in the first stage of Galileo project were discussed and. And then 200 GPS Weeks data in SINEX format from three IGS analysis centers COD, ESA and GFZ was used as input data, we apply loose constraint, use the variance factor of weekly time series as apriori weight in the combination, and estimate station coordinate and 7 transformation parameters together. According to this simulation, the translation and scale parameters of three analysis centers are attained by weekly combined solution, while the rotation parameters are just estimated by the data from ESA. With these 7 transformation parameters, the GTRF can be initially realized by alignment to the ITRF by the GSS co-located with ITRF core stations.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.