The Broadcast Ephemeris Design of LEO Navigation Augmentation Satellites Based on the Integration-type Ephemeris Model

2021 ◽  
Author(s):  
Lingdong Meng ◽  
Junping Chen ◽  
Jiexian Wang ◽  
Yize Zhang
Keyword(s):  
Broadcast Ephemeris

scholarly journals A long‐term broadcast ephemeris model for extended operation of GNSS satellites

Navigation ◽  
2020 ◽  
Author(s):  
Oliver Montenbruck ◽  
Peter Steigenberger ◽  
Moritz Aicher
Keyword(s):  
Broadcast Ephemeris ◽  
Extended Operation

scholarly journals BeiDou Satellite Unhealthy States and the Impact on System Performance

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4196 ◽  
Author(s):  
Caibo Hu ◽  
Chuang Shi ◽  
Jinping Chen ◽  
Yidong Lou ◽  
Fei Wang
Keyword(s):  
System Performance ◽  
Satellite Orbit ◽  
Service Area ◽  
The Other ◽  
Classification Method ◽  
Positioning Accuracy ◽  
General Classification ◽  
Broadcast Ephemeris ◽  
Beidou System ◽  
The Impact

The BeiDou system satellites may be unhealthy due to many reasons, affecting system performance in different ways. Therefore, it is important to analyze the causes and characteristics of the satellites’ unhealthy states. In this study, these states are classified into five types based on the broadcast ephemeris. Three criteria are presented, based on which a general classification method is proposed. Data from July 2017 to June 2018 are analyzed to validate the method, from which we know that the average unhealthy duration due to satellite maneuvers is much longer than the duration of unhealthy states related to satellite orbit or clock anomalies, and the other unhealthy states may be caused by inbound or outbound satellites. Statistics show that most of the time, the number of unhealthy satellites is no more than two and the average positioning accuracy in the service area will decrease by no more than 0.75 and 1.2 meters when one or two BDS satellites are unhealthy, respectively.

scholarly journals Initial Results of Modeling and Improvement of BDS-2/GPS Broadcast Ephemeris Satellite Orbit Based on BP and PSO-BP Neural Networks

2021 ◽  
Vol 13 (23) ◽  
pp. 4801
Author(s):  
Hanlin Chen ◽  
Fei Niu ◽  
Xing Su ◽  
Tao Geng ◽  
Zhimin Liu ◽  
...  
Keyword(s):  
Neural Network ◽  
Network Model ◽  
Neural Network Model ◽  
Bp Neural Network ◽  
Network Models ◽  
Neural Network Models ◽  
Orbit Error ◽  
Broadcast Ephemeris ◽  
Bp Neural Network Model ◽  
Orbit Errors

With the rapid development and gradual perfection of GNSS in recent years, improving the real-time service performance of GNSS has become a research hotspot. In GNSS single-point positioning, broadcast ephemeris is used to provide a space–time reference. However, the orbit parameters of broadcast ephemeris have meter-level errors, and no mathematical model can simulate the variation of this, which restricts the real-time positioning accuracy of GNSS. Based on this research background, this paper uses a BP (Back Propagation) neural network and a PSO (Particle Swarm Optimization)–BP neural network to model the variation in the orbit error of GPS and BDS broadcast ephemeris to improve the accuracy of broadcast ephemeris. The experimental results showed that the two neural network models in GPS can model the broadcast ephemeris orbit errors, and the results of the two models were roughly the same. The one-day and three-day improvement rates of RMS(3D) were 30–50%, but the PSO–BP neural network model was better able to model the trend of errors and effectively improve the broadcast ephemeris orbit accuracy. In BDS, both of the neural network models were able to model the broadcast ephemeris orbit errors; however, the PSO–BP neural network model results were better than those of the BP neural network. In the GEO satellite outcome of the PSO–BP neural network, the STD and RMS of the orbit error in three directions were reduced by 20–70%, with a 20–30% improvement over the BP neural network results. The IGSO satellite results showed that the PSO–BP neural network model output accuracy of the along- and radial-track directions experienced a 70–80% improvement in one and three days. The one- and three-day RMS(3D) of the MEO satellites showed that the PSO–BP neural network has a greater ability to resist gross errors than that of the BP neural network for modeling the changing trend of the broadcast ephemeris orbit errors. These results demonstrate that using neural networks to model the orbit error of broadcast ephemeris is of great significance to improving the orbit accuracy of broadcast ephemeris.

scholarly journals Self-Assisted First-Fix Method for A-BDS Receivers with Medium- and Long-Term Ephemeris Extension

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Zilong Shen ◽  
Jing Peng ◽  
Wenxiang Liu ◽  
Feixue Wang ◽  
Shibing Zhu ◽  
...  
Keyword(s):  
Dynamic Models ◽  
Rapid Development ◽  
Real Data ◽  
Satellite System ◽  
Time Interval ◽  
Signal Acquisition ◽  
Positioning Accuracy ◽  
Broadcast Ephemeris ◽  
Intelligent Logistics

As a sensor for standalone position and velocity determination, the BeiDou Navigation Satellite System (BDS) receiver is becoming an important part of the intelligent logistics systems under rapid development in China. The applications in the mass market urgently require the BDS receivers to improve the performance of such functions, that is, shorter Time to First Fix (TTFF) and faster navigation signal acquisition speed with Ephemeris Extension (EE) in standalone mode. As a practical way to improve such functions of the Assisted BDS (A-BDS) receivers without the need for specialized hardware support, a Self-Assisted First-Fix (SAFF) method with medium- and long-term EE is proposed in this paper. In this SAFF method, the dynamic Medium- and Long-Term Orbit Prediction (MLTOP) method, which uses the historical broadcast ephemeris data with the optimal configuration of the dynamic models and orbit fitting time interval, is utilized to generate the extended ephemeris. To demonstrate the performance of the MLTOP method used in the SAFF method, a suit of tests, which were based on the real data of broadcast ephemeris and precise ephemeris, were carried out. In terms of the positioning accuracy, the overall performance of the SAFF method is illustrated. Based on the characteristics of the medium- and long-term EE, the simulation tests for the SAFF method were conducted. Results show that, for the SAFF method with medium- and long-term EE of the BeiDou MEO/IGSO satellites, the horizontal positioning accuracy is about 12 meters, and the overall positioning accuracy is about 25 meters. The results also indicate that, for the BeiDou satellites with different orbit types, the optimal configurations of the MLTOP method are different.

scholarly journals Space State Representation Corrections as an Aid in Pseudolite Positioning

Sensors ◽  
2019 ◽  
Vol 19 (19) ◽  
pp. 4158
Author(s):  
Jacek Rapiński ◽  
Dariusz Tomaszewski
Keyword(s):  
Specific Situation ◽  
Technical Standard ◽  
State Representation ◽  
Low Resolution ◽  
Gnss Receiver ◽  
Numerical Example ◽  
Broadcast Ephemeris ◽  
Space State ◽  
Implementation Problems

In the presented study, the authors deal with the problem of transmission of pseudolite coordinates to the receiver. Nowadays, there is no uniquely specified method that would provide data about the position of the pseudolite to the GNSS receiver. There is also no technical standard that defines the explicit way of performing such transmission. Solutions presented in the literature are usually tailored to the described system, which is then suited to the specific situation. The article shows that the universal methods, involving the modification of transmitted broadcast ephemeris data, cannot be universally used. The modifications could not have been introduced due to the low resolution of the quantities that are transmitted in the ephemeris data, in relation to the values that would have to be sent by the pseudolite. To overcome the implementation problems, the authors propose two solutions. The first solution presented is the modification of the RTCM SSR frame. This approach allows replacing one of the existing satellites in space with the pseudolite, while the second method involves the use of new RTCM frame for sending the pseudolite position. Finally, a numerical example of the proposed solutions is presented. At the end of the manuscript, their advantages and implementation possibilities are discussed.

An 18-element GEO broadcast ephemeris based on non-singular elements

GPS Solutions ◽  
2014 ◽  
Vol 19 (1) ◽  
pp. 49-59 ◽  
Author(s):  
Lan Du ◽  
Zhongkai Zhang ◽  
Jin Zhang ◽  
Li Liu ◽  
Rui Guo ◽  
...  
Keyword(s):  
Broadcast Ephemeris

scholarly journals Analysis of Factors Affecting Asynchronous RTK Positioning with GNSS Signals

2019 ◽  
Vol 11 (10) ◽  
pp. 1256
Author(s):  
Shu ◽  
Liu ◽  
Feng ◽  
Xu ◽  
Qian ◽  
...  
Keyword(s):  
Satellite Orbit ◽  
Latency Time ◽  
Short Baseline ◽  
Factors Affecting ◽  
Broadcast Ephemeris ◽  
Geo Satellites ◽  
Short Baselines ◽  
Broadcast Orbit ◽  
Different Characteristics ◽  
Clock Offset

For short baseline real-time kinematic (RTK) positioning, the atmosphere and broadcast ephemeris errors can be usually eliminated in double-differenced (DD) processing for synchronous observations. However, in the case of possible communication latency time, these errors may not be eliminated in DD treatments due to their variations during latency time. In addition, the time variation of these errors may present different characteristics among GPS, GLONASS, BDS, and GALILEO due to different satellite orbit and clock types. In this contribution, the formulas for studying the broadcast orbit and clock offset errors and atmosphere error in asynchronous RTK (ARTK) model is proposed, and comprehensive experimental analysis is performed to numerically show time variations of these errors and their impacts on RTK results from short-baselines among four systems. Compared with synchronous RTK, the degradation of position precision for ARTK can reach a few centimeters, but the accuracy degradation to a different degree by different systems. BDS and Galileo usually outperform GPS and GLONASS in ARTK due to the smaller variation of broadcast ephemeris error. The variation of broadcast orbit error is generally negligible compared with the variation of broadcast clock offset error for GPS, BDS, and Galileo. Specifically, for a month of data, the root mean square (RMS) values for the variation of broadcast ephemeris error over 15 seconds are 11.2, 16.9, 7.3, and 3.0 mm for GPS, GLONASS, BDS, and Galileo, respectively. The variation of ionosphere error for some satellites over 15 seconds can reach a few centimeters during active sessions under a normal ionosphere day. In addition, compared with other systems, BDS ARTK shows an advantage under high ionosphere activity, and such advantage may be attributed to five GEO satellites in the BDS constellation.

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