scholarly journals Preliminary evaluation of Doppler-determined pole positions computed using World Geodetic System 1984

1988 ◽  
Vol 128 ◽  
pp. 131-140
Author(s):  
John A. Bangert ◽  
James P. Cunningham
Keyword(s):  
Orbit Determination ◽  
Satellite Orbit ◽  
Satellite System ◽  
Pole Position ◽  
Preliminary Evaluation ◽  
Geodetic System ◽  
Determination Process ◽  
The World ◽  
Gravitational Model ◽  
Terrestrial Reference System

Since 1975, the Defense Mapping Agency (DMA) has been determining polar motion as a byproduct of computing the precise orbits of the Navy Navigation Satellite System (NNSS) satellites. The orbit determination process currently incorporates the NSWC 9Z2 terrestrial reference system and the NWL 10E-1 Earth Gravitational Model (EGM) to degree 28 and order 27. The World Geodetic System 1984 (WGS 84), developed by DMA, will replace the NSWC 9Z2/10E-1 system for NNSS orbit determination. The WGS 84 EGM to degree and order 41 will be utilized. This paper presents the results of two experiments which compared pole positions computed in the two systems. These comparisons indicate that use of WGS 84 improves agreement between pole position values resulting from the Nova-class satellite orbit solutions and the values determined by other modern techniques.

Simulation of Orbit Determination of HaiYang-2 Satellite on DORIS

2013 ◽  
Vol 353-356 ◽  
pp. 3456-3459 ◽  
Author(s):  
Qiao Li Kong ◽  
Jin Yun Guo ◽  
Li Tao Han
Keyword(s):  
Orbit Determination ◽  
Tracking System ◽  
Precise Orbit Determination ◽  
Computation Time ◽  
Satellite Orbit ◽  
The World ◽  
Space Geodetic Techniques ◽  
Orbit Tracking ◽  
The Relationship

DORIS is a kind of advanced space-geodetic techniques applied in satellite orbit tracking and measuring. As the first ocean dynamic environmental satellite in China, the HY-2 satellite is equipped with the Doppler orbitography and radiopositioning integrated by satellite (DORIS) tracking system for the precise orbit determination. In particular, the investigation of our work has focused on accuracy analysis of orbit determination using simulated DORIS data given different observation noises, besides the relationship is investigated between accuracy and computation time and the number of ground beacons evenly distributed around the world. Experiment results show that observation noises can affect the accuracy of orbit determination directly, and the number of DORIS ground beacons decides the accuracy and computation time of obit determination in the condition of ground beacons are evenly distributed around the world, therefore, during the process of obit determination, we should optimize the ground beacon station distribution to achieve the best accuracy of obit determination using DORIS tracking data.

scholarly journals Investigating the GALILEO and BeiDou orbit accuracy derived from rapid products

2020 ◽  
Vol 3 (1) ◽  
pp. 316-321
Author(s):  
Sermet Ogutcu ◽  
Salih Alcay ◽  
Omer Faruk Atiz
Keyword(s):  
Orbit Determination ◽  
Precise Orbit Determination ◽  
Solar Radiation Pressure ◽  
Satellite Orbit ◽  
Satellite System ◽  
Precise Orbit ◽  
Yaw Attitude ◽  
Global Navigation Satellite ◽  
Cross Track ◽  
Mean Square Errors

In recent years, the advances of the new Global Navigation Satellite System (GNSS) constellations including, Galileo and BeiDou (BDS), have undergone dramatic changes. Some analysis centers (ACs) produce precise orbit and clock products of Galileo and BeiDou constellations. Currently, three types of Galileo and BeiDou satellite orbit and clock products are available – namely, precise, rapid and ultra-rapid products –. Ultra-rapid and rapid products are generally used for time-constrained applications. Precise orbit determination (POD) of Galileo and BeiDou is much challenging compared with GPS and GLONASS constellations due to the officially undetermined receiver phase center offset (PCO), variations (PCV) of Galileo and BeiDou constellations and, also some other not well-defined factors such as yaw-attitude models and solar radiation pressure. In this study, GALILEO orbit accuracy is investigated using rapid products produced by Center for Orbit Determination in Europe (CODE) GeoForschungsZentrum (GFZ) and Wuhan University (WUHAN), while GFZ and WUHAN rapid products are used for BeiDou constellation only. One month (January) of data in 2020 is used to compute errors of radial, along-track, and cross-track components of Galileo and BeiDou orbit derived by rapid products compared with the CODE final Multi-GNSS Experiment (MGEX) product which is assumed as the reference product. The results show that no significant differences between the products are found for Galileo orbit. For BeiDou orbit, WUHAN rapid product produced the smaller root mean square errors (RMSEs) of orbit components compared with the GFZ rapid product.

scholarly journals Precise Orbit Determination and Maneuver Assessment for TH-2 Satellites Using Spaceborne GPS and BDS2 Observations

2021 ◽  
Vol 13 (24) ◽  
pp. 5002
Author(s):  
Houzhe Zhang ◽  
Defeng Gu ◽  
Bing Ju ◽  
Kai Shao ◽  
Bin Yi ◽  
...  
Keyword(s):  
Relative Error ◽  
Orbit Determination ◽  
Single Point ◽  
Three Dimensional ◽  
Precise Orbit Determination ◽  
Satellite Orbit ◽  
Satellite System ◽  
Precise Orbit ◽  
Velocity Changes ◽  
Better Than

The TH-2 satellite system, including the TH-2A and TH-2B, is the first distributed interferometric synthetic aperture radar (InSAR) satellite system in China. During the in-orbit operation, the TH-2A satellite should perform three maneuvers per day to keep the formation flying geometry. We estimate those maneuvers in the precise orbit determination (POD) by the GPS and BDS2 measurements on board, respectively. The residuals of the POD show that the effects caused by orbital maneuvers can be well eliminated for both the GPS and BDS2 data. The precision of the BDS2-based POD is better than 8.0 cm in the three-dimensional direction (3D) compared with the orbit derived from the GPS observations. Such a precision level of the satellite orbit satisfies the InSAR mission requirement of the TH-2. In addition, the relative error of velocity changes is employed to evaluate the maneuver estimations by the POD using the regional navigation system of BDS2. The results show that the relative error of velocity changes between the GPS- and BDS2-based POD is less than 7.0%, which indicates that the maneuver performance extracted from the regional BDS2 data is as good as that extracted from the global GPS data. In the GNSS fused processing, we found that the independent receiver clock offsets should be taken into account, since the time tag corrections for the GPS and BDS2 observations collected on the TH-2 spaceborne receivers were different. The precision of the GPS and BDS2 (GC) combined single point positioning (SPP) can be improved by 12–14% compared with the GPS-only solution when the position dilution of precision (PDOP) of GPS exceeds three. The overlap comparisons of the GC combined orbits show that the internal orbit precision of the TH-2 satellites is better than 0.7 cm. However, the improvement of the GC combined POD result is only 3–4% with respect to the GPS-only solution, which is limited to the precision of the precise orbit and clock products of BDS2 at the present stage.

Comparative analysis and interpretation of grace and grace-fo data

2020 ◽  
Vol 4 ◽  
pp. 101-106
Author(s):  
Konstantin Simonov ◽  
◽  
Alexander Matsulev
Keyword(s):  
Comparative Analysis ◽  
World Ocean ◽  
Satellite System ◽  
Data Archive ◽  
Space Systems ◽  
Satellite Measurements ◽  
Digital Maps ◽  
The World ◽  
Grace Mission ◽  
Anomalous State

The study is devoted to the analysis of the features of the change in the Equivalent Water Height (EWH) parameter over the geoid based on satellite measurements of space systems. The study used the GRACE and GRACE-FO satellite data archive. The assessment was carried out on Earth as a whole, including land areas and the World Ocean. Interpretation of the anomalous state of the geoenvironment is performed using digital maps of the spatial distribution of the EWH parameter based on the histogram approach and correlation analysis. Also, a comparative analysis of the studied data from the GRACE mission and data from the new GRACE-FO satellite system launched into orbit in the summer of 2018 was carried out.

scholarly journals Estimation of fractional cycle bias for GPS/BDS-2/Galileo based on international GNSS monitoring and assessment system observations using the uncombined PPP model

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Jin Wang ◽  
Qin Zhang ◽  
Guanwen Huang
Keyword(s):  
Estimation Method ◽  
Satellite Orbit ◽  
Satellite System ◽  
Assessment System ◽  
Navigation Satellite ◽  
Dual Frequency ◽  
Fractional Cycle Bias ◽  
The Stability ◽  
High Consistency ◽  
Global Navigation Satellite

AbstractThe Fractional Cycle Bias (FCB) product is crucial for the Ambiguity Resolution (AR) in Precise Point Positioning (PPP). Different from the traditional method using the ionospheric-free ambiguity which is formed by the Wide Lane (WL) and Narrow Lane (NL) combinations, the uncombined PPP model is flexible and effective to generate the FCB products. This study presents the FCB estimation method based on the multi-Global Navigation Satellite System (GNSS) precise satellite orbit and clock corrections from the international GNSS Monitoring and Assessment System (iGMAS) observations using the uncombined PPP model. The dual-frequency raw ambiguities are combined by the integer coefficients (4,− 3) and (1,− 1) to directly estimate the FCBs. The details of FCB estimation are described with the Global Positioning System (GPS), BeiDou-2 Navigation Satellite System (BDS-2) and Galileo Navigation Satellite System (Galileo). For the estimated FCBs, the Root Mean Squares (RMSs) of the posterior residuals are smaller than 0.1 cycles, which indicates a high consistency for the float ambiguities. The stability of the WL FCBs series is better than 0.02 cycles for the three GNSS systems, while the STandard Deviation (STD) of the NL FCBs for BDS-2 is larger than 0.139 cycles. The combined FCBs have better stability than the raw series. With the multi-GNSS FCB products, the PPP AR for GPS/BDS-2/Galileo is demonstrated using the raw observations. For hourly static positioning results, the performance of the PPP AR with the three-system observations is improved by 42.6%, but only 13.1% for kinematic positioning results. The results indicate that precise and reliable positioning can be achieved with the PPP AR of GPS/BDS-2/Galileo, supported by multi-GNSS satellite orbit, clock, and FCB products based on iGMAS.

scholarly journals General relativistic effects acting on the orbits of Galileo satellites

2021 ◽  
Vol 133 (4) ◽  
Author(s):  
K. Sośnica ◽  
G. Bury ◽  
R. Zajdel ◽  
K. Kazmierski ◽  
J. Ventura-Traveset ◽  
...  
Keyword(s):  
General Relativity ◽  
Orbit Determination ◽  
Final Height ◽  
Precise Orbit Determination ◽  
Satellite System ◽  
De Sitter ◽  
Circular Orbits ◽  
Precise Orbit ◽  
Artificial Earth Satellites ◽  
Artificial Earth

AbstractThe first pair of satellites belonging to the European Global Navigation Satellite System (GNSS)—Galileo—has been accidentally launched into highly eccentric, instead of circular, orbits. The final height of these two satellites varies between 17,180 and 26,020 km, making these satellites very suitable for the verification of the effects emerging from general relativity. We employ the post-Newtonian parameterization (PPN) for describing the perturbations acting on Keplerian orbit parameters of artificial Earth satellites caused by the Schwarzschild, Lense–Thirring, and de Sitter general relativity effects. The values emerging from PPN numerical simulations are compared with the approximations based on the Gaussian perturbations for the temporal variations of the Keplerian elements of Galileo satellites in nominal, near-circular orbits, as well as in the highly elliptical orbits. We discuss what kinds of perturbations are detectable using the current accuracy of precise orbit determination of artificial Earth satellites, including the expected secular and periodic variations, as well as the constant offsets of Keplerian parameters. We found that not only secular but also periodic variations of orbit parameters caused by general relativity effects exceed the value of 1 cm within 24 h; thus, they should be fully detectable using the current GNSS precise orbit determination methods. Many of the 1-PPN effects are detectable using the Galileo satellite system, but the Lense–Thirring effect is not.

scholarly journals An In-Depth Assessment of the New BDS-3 B1C and B2a Signals

2021 ◽  
Vol 13 (4) ◽  
pp. 788
Author(s):  
Qinghua Zhang ◽  
Yongxing Zhu ◽  
Zhengsheng Chen
Keyword(s):  
Carrier Phase ◽  
Density Ratio ◽  
Signal Strength ◽  
Satellite Orbit ◽  
Satellite System ◽  
Earth Orbit ◽  
Base Line ◽  
Signal Characteristics ◽  
Better Than

An in-depth and comprehensive assessment of new observations from BDS-3 satellites is presented, with the main focus on the Carrier-to-Noise density ratio (C/N0), the quality of code and carrier phase observations for B1C and B2a signal. The signal characteristics of geosynchronous earth orbit (GEO), inclined geosynchronous satellite orbit (IGSO) and medium earth orbit (MEO) satellites of BDS-3 were grouped and compared, respectively. The evaluation results of the new B1C and B2a signals of BDS-3 were compared with the previously B1I/B2I/B3I signals and the interoperable signals of GPS, Galileo and quasi-zenith satellite system (QZSS) were compared simultaneously. As expected, the results clearly show that B1C and B2a have better signal strength and higher accuracy, including code and carrier phase observations. The C/N0 of the B2a signal is about 3 dB higher than other signals. One exception is the code observation accuracy of B3I, which value is less than 0.15 m. The carrier precision of B1C and B2a is better than that of B1I/B2I/B3I. Despite difference-in-difference (DD) observation quantity or zero-base line evaluation is adopted, while B1C is about 0.3 mm higher carrier precision than B2a. The BDS-3 MEO satellite and GPS, Galileo, and QZSS satellites have the same level of signal strength, code and phase observation accuracy at the interoperable frequency, namely 1575.42 MHz and 1176.45 MHz which are very suitable for the co-position application.

scholarly journals BDS B1I multipath channel statistical model comparison between static and dynamic scenarios in dense urban canyon environment

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Xin Chen ◽  
Di He ◽  
Ling Pei
Keyword(s):  
Model Comparison ◽  
Satellite Orbit ◽  
Estimation Algorithm ◽  
Intermediate Frequency ◽  
Satellite System ◽  
Multipath Channel ◽  
Navigation Satellite ◽  
Navigation Systems ◽  
Distribution Models ◽  
Channel Models

Abstract Global Navigation Satellite System (GNSS) multipath channel models are fundamental and critical for signal simulation and receiver performance evaluation. They also aid the designing of suitable multipath error mitigation algorithms when the properties of multipath channel are available. However, there is insufficient existing research on BeiDou Navigation Satellite System (BDS) signal multipath channel models. In this study, multipath channel statistical models are established on the basis of extensive datasets of the BDS B1I signal. A multipath parameter estimation algorithm is designed to extract information of multipath rays from the intermediate frequency data. The delay, power loss, Doppler fading frequency, and lifetime distribution models for static and dynamic vehicle platforms are established and compared, and the effects of the satellite orbit type and platform speed on the models are analyzed. The results reveal the detailed distribution and variation characteristics of the multipath parameters and are valuable for the development of accurate urban navigation systems.

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