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.
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: 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.
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