A Three-Step Method for Determining Unhealthy Time Period of GPS Satellite Orbit in Broadcast Ephemeris and Its Preliminary Applications for Precise Orbit Determination

Abnormal information of satellite orbits inevitably appears in the broadcast ephemeris. Failure to obtain unhealthy information on GPS satellite orbits in precise orbit determination (POD) degrades GPS service performance. At present, the reliable unhealthy information published by the Center for Orbit Determination in Europe (CODE) is usually used, but it has at least one-day latency, and the current level of unhealthy information cannot fully meet the requirements of rapid and real-time geodetic applications, especially for non-IGS (International global navigation satellite systems (GNSS) Service) analysis centers and BeiDou navigation satellite system (BDS) users. Furthermore, the unhealthy orbit information detected by the traditional method, which is based on the synchronized pseudo-range residuals and regional observation network, cannot meet the requirement of setting separate sub-arcs in POD. In view of these problems, we propose a three-step method for determining unhealthy time periods of GPS satellite orbit in broadcast ephemeris during POD to provide reliable unhealthy information in near-real time. This method is a single-epoch solution, and it can detect unhealthy time periods in each sampling of observation in theory. It was subsequently used to detect unhealthy time periods for satellites G09 and G01 based on the 111 globally distributed tracking stations in the IGS. The performance of the new method was evaluated using cross-validation. Based on the test results, it detected an orbital leap for G09 in the broadcast ephemeris from 09:59:42 to 14:00:42 on 25 August 2017. Compared to the traditional method, the unhealthy start time using the three-step method was in better agreement with the information provided by CODE’s satellite crux files. G01 did not appear to have an orbital leap on the specified date, but it was misjudged by the traditional method. Furthermore, compared to the traditional method, the three-step method can perform unhealthy time period detection for a satellite all day long. In addition, precise orbit determination for unhealthy satellites is realized successfully with the unhealthy orbit arc information identified in this study. Compared to the CODE orbit, the root mean square and standard deviation of the new method for G09 are less than 2 cm, and the three-step method shows an improvement in accuracy compared with the traditional method. From the above results, it can be seen that this study can provide a feasible approach to meet the real-time unhealthy time period detection requirements of a satellite orbit in a broadcast ephemeris during POD. Furthermore, compared to waiting for updates of CODE’s satellite crux files or for accumulating delayed observation data, it has the potential to provide additional information in the process of generating ultra-rapid/real-time orbits.

Download Full-text

Comparison of the real-time Precise Orbit Determination for LEO between Kinematic and Reduced-Dynamic modes

Measurement ◽

10.1016/j.measurement.2021.110224 ◽

2021 ◽

pp. 110224

Author(s):

Zhiyu Wang ◽

Zishen Li ◽

Liang Wang ◽

Ningbo Wang ◽

Yang Yang ◽

...

Keyword(s):

Real Time ◽

Orbit Determination ◽

Precise Orbit Determination ◽

The Real ◽

Precise Orbit ◽

Reduced Dynamic

Download Full-text

Real-Time Kinematic Precise Orbit Determination for LEO Satellites Using Zero-Differenced Ambiguity Resolution

Remote Sensing ◽

10.3390/rs11232815 ◽

2019 ◽

Vol 11 (23) ◽

pp. 2815 ◽

Cited By ~ 1

Author(s):

Xingxing Li ◽

Jiaqi Wu ◽

Keke Zhang ◽

Xin Li ◽

Yun Xiong ◽

...

Keyword(s):

Real Time ◽

Ambiguity Resolution ◽

Orbit Determination ◽

Precise Orbit Determination ◽

The Real ◽

Precise Orbit ◽

Ambiguity Fixing ◽

Real Time Kinematic ◽

Leo Satellites ◽

Fixed Solution

The rapid growing number of earth observation missions and commercial low-earth-orbit (LEO) constellation plans have provided a strong motivation to get accurate LEO satellite position and velocity information in real time. This paper is devoted to improve the real-time kinematic LEO orbits through fixing the zero-differenced (ZD) ambiguities of onboard Global Navigation Satellite System (GNSS) phase observations. In the proposed method, the real-time uncalibrated phase delays (UPDs) are estimated epoch-by-epoch via a global-distributed network to support the ZD ambiguity resolution (AR) for LEO satellites. By separating the UPDs, the ambiguities of onboard ZD GPS phase measurements recover their integer nature. Then, wide-lane (WL) and narrow-lane (NL) AR are performed epoch-by-epoch and the real-time ambiguity–fixed orbits are thus obtained. To validate the proposed method, a real-time kinematic precise orbit determination (POD), for both Sentinel-3A and Swarm-A satellites, was carried out with ambiguity–fixed and ambiguity–float solutions, respectively. The ambiguity fixing results indicate that, for both Sentinel-3A and Swarm-A, over 90% ZD ambiguities could be properly fixed with the time to first fix (TTFF) around 25–30 min. For the assessment of LEO orbits, the differences with post-processed reduced dynamic orbits and satellite laser ranging (SLR) residuals are investigated. Compared with the ambiguity–float solution, the 3D orbit difference root mean square (RMS) values reduce from 7.15 to 5.23 cm for Sentinel-3A, and from 5.29 to 4.01 cm for Swarm-A with the help of ZD AR. The SLR residuals also show notable improvements for an ambiguity–fixed solution; the standard deviation values of Sentinel-3A and Swarm-A are 4.01 and 2.78 cm, with improvements of over 20% compared with the ambiguity–float solution. In addition, the phase residuals of ambiguity–fixed solution are 0.5–1.0 mm larger than those of the ambiguity–float solution; the possible reason is that the ambiguity fixing separate integer ambiguities from unmodeled errors used to be absorbed in float ambiguities.

Download Full-text

Towards the GEOSAT Follow-On Precise Orbit Determination Goals of High Accuracy and Near-Real-Time Processing

AIAA/AAS Astrodynamics Specialist Conference and Exhibit ◽

10.2514/6.2006-6402 ◽

2006 ◽

Cited By ~ 4

Author(s):

Frank Lemoine ◽

Nikita Zelensky ◽

Douglas Chinn ◽

Brian Beckley ◽

John Lillibridge

Keyword(s):

Real Time ◽

Orbit Determination ◽

Precise Orbit Determination ◽

High Accuracy ◽

Real Time Processing ◽

Time Processing ◽

Precise Orbit

Download Full-text

Effects of New Level-1B Data on GRACE Temporal Gravity Field Models and Precise Orbit Determination Solutions

Remote Sensing ◽

10.3390/rs13204119 ◽

2021 ◽

Vol 13 (20) ◽

pp. 4119

Author(s):

Nannan Guo ◽

Xuhua Zhou ◽

Kai Li

Keyword(s):

Gravity Field ◽

Orbit Determination ◽

Field Model ◽

Precise Orbit Determination ◽

Satellite Orbit ◽

Data Types ◽

Gravity Field Model ◽

Precise Orbit ◽

Temporal Gravity ◽

Gravity Field Models

The quality of Gravity Recovery and Climate Experiment (GRACE) observation is the prerequisite for obtaining the high-precision GRACE temporal gravity field model. To study the influence of new-generation GRACE Level-1B Release 03 (RL03) data and the new atmosphere and ocean de-aliasing (AOD1B) products on recovering temporal gravity field models and precise orbit determination (POD) solutions, we combined the global positioning system and K-band ranging-rate (KBRR) observations of GRACE satellites to estimate the effect of different data types on these solutions. The POD and monthly gravity field solutions are obtained from 2005 to 2010 by SHORDE software developed by the Shanghai Astronomical Observatory. The post-fit residuals of the KBRR data were decreased by approximately 10%, the precision of three-direction positions of the GRACE POD was improved by approximately 5%, and the signal-to-noise ratio of the monthly gravity field model was enhanced. The improvements in the new release of monthly gravity field model and POD solutions can be attributed to the enhanced Level-1B KBRR data and the AOD1B model. These improvements were primarily due to the enhanced of KBRR data; the effect of the AOD1B model was not significant. The results also showed that KBRR data slightly improve the satellite orbit precision, and obviously enhance the precision of the gravity field model.

Download Full-text

Investigating the GALILEO and BeiDou orbit accuracy derived from rapid products

Academic Perspective Procedia ◽

10.33793/acperpro.03.01.62 ◽

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 &ndash; namely, precise, rapid and ultra-rapid products &ndash;. 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.

Download Full-text

Real-time precise orbit determination for BDS satellites using the square root information filter

GPS Solutions ◽

10.1007/s10291-019-0827-1 ◽

2019 ◽

Vol 23 (2) ◽

Cited By ~ 3

Author(s):

Xiaolei Dai ◽

Yidong Lou ◽

Zhiqiang Dai ◽

Yun Qing ◽

Min Li ◽

...

Keyword(s):

Real Time ◽

Orbit Determination ◽

Precise Orbit Determination ◽

Square Root ◽

Precise Orbit ◽

Information Filter

Download Full-text

The Preliminary Results for Five-System Ultra-Rapid Precise Orbit Determination of the One-Step Method Based on the Double-Difference Observation Model

Remote Sensing ◽

10.3390/rs11010046 ◽

2018 ◽

Vol 11 (1) ◽

pp. 46 ◽

Cited By ~ 3

Author(s):

Fei Ye ◽

Yunbin Yuan ◽

Bingfeng Tan ◽

Zhiguo Deng ◽

Jikun Ou

Keyword(s):

Orbit Determination ◽

Precise Orbit Determination ◽

Double Difference ◽

Observation Model ◽

Software Platform ◽

Step Method ◽

Precise Orbit ◽

One Step ◽

The One ◽

Prototype Software

The predicted parts of ultra-rapid orbits are important for (near) real-time Global Navigation Satellite System (GNSS) precise applications; and there is little research on GPS/GLONASS/BDS/Galileo/QZSS five-system ultra-rapid precise orbit determination; based on the one-step method and double-difference observation model. However; the successful development of a software platform for solving five-system ultra-rapid orbits is the basis of determining and analyzing these orbits. Besides this; the different observation models and processing strategies facilitate to validate the reliability of the various ultra-rapid orbits. In this contribution; this paper derives the double-difference observation model of five-system ultra-rapid precise orbit determination; based on a one-step method; and embeds this method and model into Bernese v5.2; thereby forming a new prototype software platform. For validation purposes; 31 days of real tracking data; collected from 130 globally-distributed International GNSS Service (IGS) multi-GNSS Experiment (MGEX) stations; are used to determine a five-system ultra-rapid precise orbit. The performance of the software platform is evaluated by analysis of the orbit discontinuities at day boundaries and by comparing the consistency with the MGEX orbits from the Deutsches GeoForschungsZentrum (GFZ); between the results of this new prototype software platform and the ultra-rapid orbit provided by the International GNSS Monitoring and Assessment System (iGMAS) analysis center (AC) at the Institute of Geodesy and Geophysics (IGG). The test results show that the average standard deviations of orbit discontinuities in the three-dimension direction are 0.022; 0.031; 0.139; 0.064; 0.028; and 0.465 m for GPS; GLONASS; BDS Inclined Geosynchronous Orbit (IGSO); BDS Mid-Earth Orbit (MEO); Galileo; and QZSS satellites; respectively. In addition; the preliminary results of the new prototype software platform show that the consistency of this platform has been significantly improved compared to the software package of the IGGAC.

Download Full-text