Analysis and improvement of the Bancroft algorithm for GNSS satellite orbit determination

2021 ◽  
Author(s):  
Yongchang Chen ◽  
Chuanzhen Sheng ◽  
Qingwu Yi ◽  
Ran Li ◽  
Guangqing Ma ◽  
...  
Keyword(s):  
Orbit Determination ◽  
Satellite Orbit ◽  
Three Dimensions ◽  
Single Frequency ◽  
Precise Ephemeris ◽  
Accuracy Level ◽  
Receiver Clock ◽  
The Impact ◽  
Clock Offset ◽  
Initial Orbit

Abstract Satellite orbit information is crucial for ensuring that global navigation satellite systems (GNSSs) provide appropriate positioning, navigation and timing services. Typically, users can obtain access to orbit information of a specific accuracy level from navigation messages or precise ephemeris products. Without this information, a system will not be able to provide normal service. In response to this problem, initial orbit information of a certain level of precision must be obtained to support subsequent applications, such as broadcasting or precise ephemeris calculations, thereby ensuring the successful subsequent operation of the navigation system. One of two ways to calculate the initial orbit of a GNSS satellite is to utilize ground tracking stations to observe satellite vector information in the geocentric inertial system; the second way is to utilize GNSS range observations and known orbit information from other satellites. For the second approach, some researchers use the Bancroft algorithm combined with receiver clock offset to determine the initial orbit of GNSS satellites. Because this method requires an additional known receiver clock offset, we study the dependence of the Bancroft algorithm on clock offset in GNSS orbit determination. By assessing the impact of errors of different magnitude on the accuracy of the orbit results, we obtain experimental conclusions. After comprehensively analyzing various errors, we determine the accuracy level that the Bancroft algorithm can achieve for orbit determination without considering receiver clock correction. Dual-frequency and single-frequency pseudorange data from IGS stations are used in orbit determination experiments. When a small receiver clock offset is considered and no correction is made, the deviations in the calculated satellite positions in three dimensions are approximately 979.3 and 1118.1 meters (dual and single frequency); with a satellite clock offset, these values are approximately 928.8 and 1062.7 meters (dual and single frequency).

Initial Orbit Determination Using Single Frequency GPS Measurements of Launch Vehicle

2014 ◽  
Vol 599-601 ◽  
pp. 964-969
Author(s):  
Guo Hu Xue ◽  
Jun Shan Mu ◽  
Hui Fen Li ◽  
Li Wei Zhu ◽  
Yang Liu
Keyword(s):  
Orbit Determination ◽  
Launch Vehicle ◽  
Single Frequency ◽  
Gps Measurements ◽  
Precise Ephemeris ◽  
Initial Orbit Determination ◽  
Orbit Segment ◽  
Radar Measurements ◽  
Initial Orbit

Orbit determination by using GPS measurements of a launch vehicle is an important option for the initial orbit determination of the vehicle's payload, and its accuracy is higher than the results generated by radar measurements. However, only broadcast GPS ephemeris and clock products are used in the current GPS measurements processing method, and Klobuchar model is directly used. The paper proposes to use precise ephemeris and clock products, and adopts an improved ionospheric model based on altitude factor for GPS measurements processing. The dynamic smoothing method is further used. The numerical results show that the proposed method can improve the early orbit satellites orbit segment to determine accuracy.

scholarly journals The Effect of BDS-3 Time Group Delay and Differential Code Bias Corrections on Positioning

2020 ◽  
Vol 11 (1) ◽  
pp. 104
Author(s):  
Peipei Dai ◽  
Jianping Xing ◽  
Yulong Ge ◽  
Xuhai Yang ◽  
Weijin Qin ◽  
...  
Keyword(s):  
Group Delay ◽  
Assessment System ◽  
Convergence Time ◽  
Single Frequency ◽  
Positioning Accuracy ◽  
Differential Code Bias ◽  
Receiver Clock ◽  
Code Bias ◽  
Point Positioning ◽  
The Impact

The timing group delay parameter (TGD) or differential code bias parameter (DCB) is an important factor that affects the performance of GNSS basic services; therefore, TGD and DCB must be taken seriously. Moreover, the TGD parameter is modulated in the navigation message, taking into account the impact of TGD on the performance of the basic service. International GNSS Monitoring and Assessment System (iGMAS) provides the broadcast ephemeris with TGD parameter and the Chinese Academy of Science (CAS) provides DCB products. In this paper, the current available BDS-3 TGD and DCB parameters are firstly described in detail, and the relationship of TGD and DCB for BDS-3 is figured out. Then, correction models of BDS-3 TGD and DCB in standard point positioning (SPP) or precise point positioning (PPP) are given, which can be applied in various situations. For the effects of TGD and DCB in the SPP and PPP solution processes, all the signals from BDS-3 were researched, and the validity of TGD and DCB has been further verified. The experimental results show that the accuracy of B1I, B1C and B2a single-frequency SPP with TGD or DCB correction was improved by approximately 12–60%. TGD will not be considered for B3I single-frequency, because the broadcast satellite clock offset is based on the B3I as the reference signal. The positioning accuracy of B1I/B3I and B1C/B2a dual-frequency SPP showed that the improvement range for horizontal components is 60.2% to 74.4%, and the vertical components improved by about 50% after the modification of TGD and DCB. In addition, most of the uncorrected code biases are mostly absorbed into the receiver clock bias and other parameters for PPP, resulting in longer convergence time. The convergence time can be max increased by up to 50% when the DCB parameters are corrected. Consequently, the positioning accuracy can reach the centimeter level after convergence, but it is critical for PPP convergence time and receiver clock bias that the TGD and DCB correction be considered seriously.

scholarly journals Improved Single-Frequency Kinematic Orbit Determination Strategy of Small LEO Satellite with the Sun-Pointing Attitude Mode

2021 ◽  
Vol 13 (19) ◽  
pp. 4020
Author(s):  
Wenju Fu ◽  
Lei Wang ◽  
Ruizhi Chen ◽  
Haitao Zhou ◽  
Tao Li ◽  
...  
Keyword(s):  
Orbit Determination ◽  
Satellite System ◽  
Single Frequency ◽  
Navigation Satellite ◽  
The Sun ◽  
Cycle Slip ◽  
Satellite Attitude ◽  
Leo Satellites ◽  
Receiver Clock ◽  
Leo Satellite

Kinematic orbit determination (KOD) of low earth orbit (LEO) satellites only using single-frequency global navigation satellite system (GNSS) data is a suitable solution for space applications demanding meter-level orbit precision. For some small LEO satellites with the sun-pointing attitude mode, the rotation of the GNSS antenna radiation pattern changes the observation noise characteristics. Since the rotation angle information of the antenna plane may not be available for most low-cost missions, the true elevation cannot be computed and a general elevation-dependent weighting model remains invalid for the onboard GNSS observations. Furthermore, the low-stability GNSS receiver clock oscillator of the LEO satellite at high speeds makes single-frequency cycle slip detection ineffective and difficult since the clock steering events occur frequently. In this study, we investigated the improved KOD strategy to improve the performance of orbit solution using single-frequency GPS and BeiDou navigation satellite system (BDS) observations collected from the Luojia-1A satellite. The weighting model based on exponential function and signal strength is proposed according to the analysis of satellite attitude impact, and a joint single-frequency detection algorithm of receiver clock jump and cycle slip is investigated as well. Based on the GPS/BDS-combined KOD results, it is demonstrated that the clock jump and cycle slip can be properly detected and observations can be effectively utilized with the proposed weighting model considering satellite attitude, which significantly improves the availability and accuracy of orbit solution. The number of available epochs is increased by 12.9% benefitting from this strategy. The orbital root mean square (RMS) precision improvements in the radial, along-track, and cross-track directions are 22.1%, 16.4%, and 6.5%, respectively. Combining BDS observations also contributes to orbit precision improvement, which reaches up to 28.8%.

Satellite Orbit Determination Using Short Arcs of GPS Data

2014 ◽  
Vol 706 ◽  
pp. 206-221
Author(s):  
Ana Paula Marins Chiaradia ◽  
Hélio Koiti Kuga ◽  
Bruna Yukiko Pinheiro Lopes Masago
Keyword(s):  
Orbit Determination ◽  
Computational Cost ◽  
Satellite Orbit ◽  
Single Frequency ◽  
Gps Data ◽  
Force Model ◽  
Gps Receiver ◽  
Tracking Station ◽  
Low Computational Cost ◽  
Special Case

This work is concerned with short arcs orbit determination using GPS signals. A special case of truncated arcs assuming that GPS data is only available when the satellite carrying the GPS receiver passes over a ground tracking station is presented. The behaviour of an Extended Kalman filter (EKF) in real time satellite orbit determination using short arcs of data is analysed. The algorithm is a simplified and compact model with low computational cost, and uses the EKF to estimate the state vector, composed of position and velocity components, and GPS receiver clock parameters. The algorithm may use different step-sizes between the GPS signal measurements. Its force model in the motion equations considered the perturbations as being due to the geopotential up to the 10thorder and degree of the spherical harmonics. The algorithm has been formerly qualified using raw single frequency pseudorange GPS measurements of the Topex/Poseidon (T/P) satellite, and used as reference in this work. However, the GPS data are truncated as if they had been collected by a single ground tracking station. In other words, the data are obtained only when the satellite T/P is within the viewing area of the station. The research results are presented showing the degradation of performance when compared to a full arc orbit determination.

scholarly journals The Impact on Geographic Location Accuracy due to Different Satellite Orbit Ephemerides

2009 ◽  
Vol 2009 ◽  
pp. 1-9
Author(s):  
Claudia C. Celestino ◽  
Cristina T. Sousa ◽  
Wilson Yamaguti ◽  
Helio Koiti Kuga
Keyword(s):  
Data Collection ◽  
Geographic Location ◽  
Satellite Orbit ◽  
Environmental Data ◽  
Location Accuracy ◽  
Doppler Shifts ◽  
Precise Ephemeris ◽  
Doppler Data ◽  
Important Input ◽  
The Impact

The current Brazilian System of Environmental Data Collection is composed of several satellites (SCD-1 and 2, CBERS-2 and 2B), Data Collection Platforms (DCPs) spread mostly over the Brazilian territory, and ground reception stations located in Cuiabá and Alcântara. An essential functionality offered to the users is the geographic location of these DCPs. The location is computed by the in-house developed “GEOLOC” program which processes the onboard measured Doppler shifts suffered by the signal transmitted by the DCPs. These data are relayed and stored on ground when the satellite passes over the receiving stations. Another important input data to GEOLOC are the orbit ephemeris of the satellite corresponding to the Doppler data. In this work, the impact on the geographic location accuracy when using orbit ephemeris which can be obtained through several sources is assessed. First, this evaluation is performed by computer simulation of the Doppler data, corresponding to real existing satellite passes. Then real Doppler data are used to assess the performance of the location system. The results indicate that the use of precise ephemeris can improve the performance of GEOLOC by reducing the location errors, and such conclusion can then be extended to similar location systems.

scholarly journals Real-Time Orbit Determination of Korean Navigation Satellite System based on Multi-GNSS Precise Point Positioning

2019 ◽  
Vol 94 ◽  
pp. 03008 ◽  
Author(s):  
Gimin Kim ◽  
Hyungjik Oh ◽  
Chandeok Park ◽  
Seungmo Seo
Keyword(s):  
Real Time ◽  
Orbit Determination ◽  
Precise Point Positioning ◽  
Satellite System ◽  
Navigation Satellite ◽  
Receiver Clock ◽  
Point Positioning ◽  
Clock Offset ◽  
Monitoring Stations

This study proposes real-time orbit/clock determination of Korean Navigation Satellite System (KNSS), which employs the kinematic precise point positioning (PPP) solutions of multiple Global Navigation Satellite System (multi-GNSS) to compensate for receiver clock offset. Global visibility of KNSS satellites in terms of geometric coverage is first analyzed for the purpose of selecting optimal locations of KNSS monitoring stations among International GNSS Service (IGS) and Multi-GNSS Experiment (MGEX) network. While the receiver clock offset is obtained from multi-GNSS PPP clock solutions of real observation data, KNSS measurements are simulated from the dynamically propagated KNSS reference orbit and the receiver clock offset. The offset and drift of satellite clock are also generated based on two-state clock model considering atomic clock noise. Real-time orbit determination results are compared with an artificially generated true or bit, wihch show 0.4m and 0.5m of 3-dimensional root-mean-square (RMS) position errors for geostationary (GEO) and ellitically-inclined-geosynchronous-orbit (EIGSO) satellites, respectively. The overall results show that the real-time precise orbit determination of KNSS should be achievable in meter level by installing KNSS-compatible multi-GNSS receivers on the IGS and/or MGEX network. The overall process can be also used to verify integrity of KNSS monitoring stations.

scholarly journals Precise Onboard Real-Time Orbit Determination with a Low-Cost Single-Frequency GPS/BDS Receiver

2019 ◽  
Vol 11 (11) ◽  
pp. 1391
Author(s):  
Xuewen Gong ◽  
Lei Guo ◽  
Fuhong Wang ◽  
Wanwei Zhang ◽  
Jizhang Sang ◽  
...  
Keyword(s):  
Real Time ◽  
Orbit Determination ◽  
Low Cost ◽  
Single Frequency ◽  
The Real ◽  
Gps Satellites ◽  
Optimal Force ◽  
Order Degree ◽  
Orbit Errors ◽  
The Impact

The low-cost single-frequency GNSS receiver is one of the most economical and affordable tools for the onboard real-time navigation of numerous remote sensing small/micro satellites. We concentrate on the algorithm and experiments of onboard real-time orbit determination (RTOD) based on a single-frequency GPS/BDS receiver. Through various experiments of processing the real single-frequency GPS/BDS measurements from the Yaogan-30 (YG30) series and FengYun-3C (FY3C) satellites of China, some critical aspects of the onboard RTOD are investigated, such as the optimal force models setting, the effect of different measurements, and the impact of GPS/BDS fusion. The results demonstrate that a gravity model truncated to 55 × 55 order/degree for YG30 and 45 × 45 for FY3C and compensated with an optimal stochastic modeling of empirical accelerations, which minimize the onboard computational load and only result in a slight loss of orbit accuracy, is sufficient to obtain high-precision real-time orbit results. Under the optimal force models, the real-time orbit accuracy of 0.4–0.7 m for position and 0.4–0.7 mm/s for velocity is achievable with the carrier-phase-based solution, while an inferior real-time orbit accuracy of 0.8–1.6 m for position and 0.9–1.7 mm/s for velocity is achieved with the pseudo-range-based solution. Furthermore, although the GPS/BDS fusion only makes little change to the orbit accuracy, it increases the number of visible GNSS satellites significantly, and thus enhances the geometric distribution of GNSS satellites that help suppress the local orbit errors and improves the reliability and availability of the onboard RTOD, especially in some anomalous arcs where only a few GPS satellites are trackable.

Robust Initial Satellite Orbit Determination method using a Modified Kalman Filter

2019 ◽  
Vol 72 (3) ◽  
pp. 528-538
Author(s):  
Shirish Potu ◽  
S.K. Anand ◽  
Soumyendu Raha
Keyword(s):  
Kalman Filter ◽  
Orbit Determination ◽  
Satellite Orbit ◽  
Navigation Systems ◽  
Determination Method ◽  
Clock Frequency ◽  
Data Set ◽  
Satellite Position ◽  
Initial Orbit Determination ◽  
Initial Orbit

The control segment in satellite navigation systems is responsible for estimating satellite orbit and clock bias which is required for a reliable Position, Navigation and Timing (PNT) user service. Initial orbit determination is a crucial step which accounts for all unknowns/anomalous parameters such as satellite orbit manoeuvres, on board and receiver clock frequency variations and environmental effects. It is vital that the estimates of the orbits and clock are insensitive to these factors. In this paper, an initial orbit determination method is presented using existing robust methodology for estimation of initial satellite position and its propagation using a variant of the Kalman Filter (KF) which allows the initial position determination process to be independent of satellite and receiver anomalies. The derivation of this KF variant is presented. Preliminary results obtained from simulated data are shown. The said method is checked for robustness by comparing results obtained for a given satellite position data set with that from the conventional Kalman Filter. The conventional KF exhibits divergence due to anomalies which are eliminated by the use of the method presented in this paper.

Angles-Only, Ground-Based, Initial Orbit Determination

1984 ◽  
Author(s):  
L. G. Taff ◽  
P. M. S. Randall ◽  
S. A. Stansfield
Keyword(s):  
Orbit Determination ◽  
Initial Orbit Determination ◽  
Initial Orbit
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