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The method and experiment analysis of two-way common-view satellite time transfer for compass system

Science China(Physics,Mechanics & Astronomy) 2015年第8期58卷 95-101页

作者： LIU Li TANG GuiFen HAN ChunHao SHI Xin GUO Rui ZHU LingFeng Beijing satellite navigation Center

Time synchronization between ground and satellites is a key technology for satellite navigation system. With dual-channel satellite, a method called Two-Way Common-View(TWCV) satellite time transfer for Compass system is proposed, which combines both characteristics of satellite common-view and two-way satellite-ground time transfer. By satellite-ground two-way pseudo-range differencing and two stations common-view differencing, this TWCV method can completely eliminate the influence of common errors, such as satellite clock offset, ephemeris errors, troposphere delay and station coordinates errors. At the same time, ionosphere delay related to signal frequency is also weakened significantly. So the precision of time transfer is improved much more greatly than before. In this paper, the basic principle is introduced in detail, the effect of major errors is analyzed and the practical calculation model in the Earth-fixed coordinate system for this new method is provided. Finally, experiment analysis is conducted with actual Compass observing data. The results show that the deviation and the stability of the satellite dual channel can be better than 0.1 ns, and the accuracy of the two-way common-view satellite time transfer can achieve 0.4 ns. All these results have verified the correctness of this TWCV method and model. In addition, we compare this TWCV satellite time transfer with the independent C-band TWSTFT(Two-Way satellite Time and Frequency Transfer). It shows that the result of the TWCV satellite time transfer is in accordance with the C-band TWSTFT result, which further suggests that the TWCV method is a remote high precision time transfer technique. The research results in this paper are very important references for the development and application of Compass satellite navigation system.

关键词： satellite navigation pseudo-range time transfer clock offset two-way common-view (TWCV)

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Multi-channel signal parameters joint optimization for GNSS terminals

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Journal of Systems Engineering and Electronics 2018年第1期29卷 39-47页

作者： WANG Qian ZHANG Chuanding XIAN Deyong Beijing satellite navigation Center Beijing 100094China

Traditional global navigation satellite system(GNSS)terminals for satellite navigation adopt independent channels to track the signals from different satellites, which results in a lack of information interaction between the channels. Inspired by the vector tracking idea, and drawing lessons from the principle that in the position domain the Taylor expanded pseudorange observations can be used for positioning via the least squares method, this paper proposes a novel least squares-based multi-channel parameter joint estimation(MPJE) method in the signal domain, which not only retains the advantages of channel fusion, but also maintains the flexibility and diversity of the localization algorithm. With achieving optimal carrier to noise ratio as the goal, the proposed method obtains the required code loop and carrier loop parameters for signal tracking in the domain of whole channels. Experimental results indicate that this method fully achieves the assistant fusion advantages of frequency lock loop(FLL), phase lock loop(PLL)and delay lock loop(DLL), making good use of the robustness and dynamic properties of the FLL and the measurement accuracy of the DLL, and is helpful for achieving stable and accurate signal tracking under weak signals and high dynamic stress environments.

关键词： least squares method signal parameter optimization vector tracking global navigation satellite system(GNSS) weight matrix

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Autonomous orbit determination study for space navigation satellite

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Journal of Beijing Institute of Technology 2016年第S2期25卷 26-30页

作者：王冬霞辛洁张之学汤廷松傅嘉政 Beijing satellite navigation Center

In order to improve the ephemeris accuracy of space navigation satellite,an autonomous orbit determination method is *** paper not only builds the bidirectional pseudo-range measurement model,but also designs the two-step Kalman filter *** satellite position and covariance are obtained in the first step by single point positioning method,which is considered as the pseudo-range measurement in second step to update orbital and time ***,the orbit orientation parameters are used to constraint the constellation rotation,solving the problem of rank deficiency of autonomous orbit *** simulation and analysis results illustrate the feasibility the proposed algorithm.

关键词： inter-satellite links Kalman filter distributed autonomous orbit determination

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Integration of InSAR and GPS for hydraulic engineering

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Science China(Technological Sciences) 2007年第z1期50卷 111-124页

作者： HE XiuFeng LUO HaiBin HUANG QiHuan HE Min Institute of satellite navigation & Spatial Information System Hohai UniversityNanjing 210098China Institute of Satellite Navigation & Spatial Information SystemHohai UniversityNanjing 210098China Institute of Satellite Navigation & Spatial Information SystemHohai UniversityNanjing 210098China Institute of Satellite Navigation & Spatial Information SystemHohai UniversityNanjing 210098China

Interferometric synthetic aperture radar (InSAR) is a potential earth observation approach, and it has been demonstrated to have a variety of applications in measuring ground movement, urban subsidence and landslides. Currently InSAR provides the ability to map accurate DEM and measure ground deformation to sub-centimeter accuracy. However, many factors affect InSAR to measure ground movement since dam constructions are built in a large scale area with a complicated climate and unstable geology. This paper discusses potential applications of integrated InSAR and GPS to monitor a large-scale ground movement due to hydropower developments. The integration of InSAR and GPS can provide a cost-effective means for monitoring deformation of hydropower developments. Moreover, two novel methods, both the improved spatial interpolating method and estimation of 3D surface motion velocities method, are proposed and the experimental results and analysis are given in this paper.

关键词： InSAR GPS hydraulic and hydropower engineering slides monitoring

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Orbit determination and prediction for Beidou GEO satellites at the time of the spring/autumn equinox

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Science China(Physics,Mechanics & Astronomy) 2015年第8期58卷 86-94页

作者： LI XiaoJie ZHOU JianHua HU XiaoGong LIU Li GUO Rui ZHOU ShanShi Beijing satellite navigation Center Shanghai Key laboratory of Space navigation and Position Techniques Shanghai Astronomical Observatory Chinese Academy of Sciences

Geostationary(GEO) satellites form an indispensable component of the constellation of Beidou navigation system(BDS). The ephemerides, or predicted orbits of these GEO satellites(GEOs), are broadcast to positioning, navigation, and timing users. User equivalent ranging error(UERE) based on broadcast message is better than 1.5 m(root formal errors: RMS) for GEO satellites. However, monitoring of UERE indicates that the orbital prediction precision is significantly degraded when the Sun is close to the Earth's equatorial plane(or near spring or autumn Equinox). Error source analysis shows that the complicated solar radiation pressure on satellite buses and the simple box-wing model maybe the major contributor to the deterioration of orbital precision. With the aid of BDS' two-way frequency and time transfer between the GEOs and Beidou time(BDT, that is maintained at the master control station), we propose a new orbit determination strategy, namely three-step approach of the multi-satellite precise orbit determination(MPOD). Pseudo-range(carrier phase) data are transformed to geometric range(biased geometric range) data without clock offsets; and reasonable empirical acceleration parameters are estimated along with orbital elements to account for the error in solar radiation pressure modeling. Experiments with Beidou data show that using the proposed approach, the GEOs' UERE when near the autumn Equinox of 2012 can be improved to 1.3 m from 2.5 m(RMS), and the probability of user equivalent range error(UERE)<2.0 m can be improved from 50% to above 85%.

关键词： Beidou system (BDS) Beidou time (BDT) geostationary (GEO) satellite spring equinox/autumn equinox solar radia-tion pressure time synchronization user equivalent ranging error

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Adaptive switching frequency buck DC-DC converter with high-accuracy on-chip current sensor

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Journal of Semiconductors 2015年第5期36卷 111-119页

作者：江金光黄飞熊智慧 Global navigation satellite System Research Center Wuhan University

A current-mode PWM buck DC-DC converter is proposed. With the high-accuracy on-chip current sen- sor, the switching frequency can be selected automatically according to load requirements. This method improves efficiency and obtains an excellent transient response. The high accuracy of the current sensor is achieved by a simple switch technique without an amplifier. This has the direct benefit of reducing power dissipation and die size. Additionally, a novel soft-start circuit is presented to avoid the inrush current at the starting up state. Finally, this DC-DC converter is fabricated with the 0.5μm standard CMOS process. The chip occupies 3.38 mm2. The accuracy of the proposed current sensor can achieve 99.5% @ 200 mA. Experimental results show that the peak efficiency is 91.8%. The input voltage ranges from 5 to 18 V, while a 2 A load current can be obtained.

关键词： DC-DC switching frequency current sensor soft-start wide load range

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GNSS Spoofing Detection Based on Consistency Check of Velocities

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Chinese Journal of Electronics 2019年第2期28卷 437-444页

作者： TAO Huiqi WU Hailing LI Hong LU Mingquan Department of Electronic Engineering Tsinghua University China satellite navigation Project Center

Spoofing attacks for Global navigation satellite system(GNSS) would cause the abnormal changes of receiver measurements. Monitoring the abnormal changes is the main pattern of anti-spoofing *** of Doppler shifts are important for GNSS spoofing detection. Most researchers focus on the consistency of Doppler such as the consistency of carrier Doppler and code rate. But the method is powerless in some *** shift measurement is proportional to change rate of pseudorange, and the relationship would be broken in the case of spoofing attack. As both Doppler measurements and pseudoranges are related to velocity of receiver,two approaches of computing velocity can be used to check the consistency of Doppler shifts and pseudoranges measurements. An efficient spoofing detection method based on the consistency check of velocities is proposed in the paper. Principle of the method is given in detail and its performance evaluations are provided as well. Simulation results demonstrate the effectiveness of the solution.

关键词： GNSS Anti-spoofing Pseudoranges Doppler Velocity Consistency

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Fast degree-distribution optimization for BATS codes

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Science China(Information Sciences) 2017年第10期60卷 124-138页

作者： Huakai ZHAO Shenghao YANG Guinian FENG Beijing satellite navigation Center The Chinese University of Hong Kong Beijing Institute of Tracking and Communication Technology

Batched sparse(BATS) codes have been proposed for communication through networks with packet loss. BATS codes include a matrix generalization of fountain codes as the outer code and random linear network coding at the intermediate network nodes as the inner code. BATS codes, however, do not possess a universal degree distribution that achieves an optimal rate for any distribution of the transfer matrix ranks. Therefore,it is important to have a fast degree-distribution optimization approach for finite-length BATS codes. In this paper, we propose the concept of batch release probability(BRP), and demonstrate some characteristics of BRPs from the degree distributions achieving nearly optimal performance. Based on these BRP characteristics,we propose a novel degree-distribution optimization approach that achieves the similar decoding performance with a much shorter optimization time, compared with the previous approach. Moreover, the universality of BRPs observed in this paper can further simplify the degree-distribution optimization of BATS codes.

关键词： network coding batched sparse(BATS) code finite-length analysis degree distribution batch release probability optimization

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Deformation Characteristics of COMPASS satellite Signals

Deformation Characteristics of COMPASS Satellite Signals

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第五届中国卫星导航学术年会

作者： Liu Jiancheng Yang Huafeng FanJianjun Zhu Dawei BeiJing satellite navigation Center

ISBN: (纸本)9783642547423

Stanford University’s study declare that navigation signals of healthy satellite may be deformed which results in ranging bias, so micro‐deformation characteristics of COMPASS satellite signal is studied based on measured data. Using of periodicity of PRN code for civil signals, data is collected at sampling rate which the interval of first point of each PRN code from the starting point is fixed. Rearranging the data, which makes that several PRN code waveforms in one data code incorporate into one PRN code waveform, so each chip has enough data pointsand data rate increases. A large‐diameterdish antenna is used, and initial phase, frequency, secondary code and information code of sampling data are removed, then data is rearranged into one PRN code period, then average for noise reduction. Finally the clean COMPASS satellite signal waveform is compared with the real GPS satellite signal waveform and the TMB fault model.

关键词： COMPASS satellite signal · sampling rate · data processing · TMB fault model

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Compass RDSS Positioning Accuracy Analysis

Compass RDSS Positioning Accuracy Analysis

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第五届中国卫星导航学术年会

作者： Guo Rui Su Ranran Liu Li Hu Guangming Chang Zhiqiao Beijing satellite navigation Center

ISBN: (纸本)9783642547393

The RDSS service is an important component in the Compass system, which is accomplished by the GEO satellites with the restriction of known elevation. The RDSS observation model was deduced, and the positioning model was given with the elevation restriction. RDSS positioning tests were implemented with real observation data, the results were as follows: 1) the PDOP value was improved greatly to 1.5, with elevation restriction;2) the RDSS observation noise is about 0.6ns, which was greater than the pseudoranging and phase ranging in the RNSS;3) the horizontal accuracy could reach 4.6 m in the Beijing region. 4) the main factors influenced the positioning accuracy include the elevation error, the time delay of both satellites and ground equipment, therefore in order to realize 10 m horizontal position accuracy, the elevation error should be less than 10 m, and the equipment time delay should be less than 10 ns.

关键词： GEO RDSS, positioning elevation equipment time delay

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