China Satellite Navigation Conference (CSNC) 2016 Proceedings: Volume I

With the development of International GNSS Service (IGS) real-time pilot project (RTPP) acquiring precipitable water vapor (PWV) with high accuracy has become a reality based on the real-time precise point pointing (RT-PPP) technique. The accuracy of zenith total delay (ZTD) and PWV derived from RT-PPP have been validated using observed global positioning system (GPS) data and meteorology data from Satellite Positioning Reference Station Network (SatRef) in 2014. The ZTD comparison with that from afterwards PPP and GAMIT software shows that the relative coefficients are 0.9786 and 0.9687, respectively. The PWV comparison with that from radiosonde shows that the relative coefficient and RMS are 0.9512 and 2.13 mm, respectively. It is a clear evidence that the RT-PPP technique has a similar accuracy with the result calculated using afterwards IGS products. However, PWV is mean of water vapor information of many GNSS signal rays during a period of time over the station, which cannot reflect the three-dimensional water vapor distribution. Slant water vapor (SWV) can be obtained by mapping PWV at different elevation and azimuth angles. The tomographic experiment has been performed using SWVs of twelve stations from SatRef as tomographic observation and compared with result from radiosonde. The comparison shows a good agreement and the RMS, SD, Bias, and MAE of integrated water vapor (IWV) are 3.60, 2.78, 2.29, and 2.92 mm, respectively, the root mean square (RMS), standard deviation (SD), Bias, and mean absolute error (MAE) of calculated water vapor density are 1.08, 1.03, −0.21, and 0.77 g/m3, respectively. The above result makes it possible that acquiring the real-time three-dimensional water vapor distribution using tomography approach with SWVs derived from RT-PPP technique, which has an important influence on short-term disastrous weather and now-casting precipitation forecasting.

Application of spread spectrum technology can effectively solve the problem of power constraints in satellite communication. A difficulty of spread spectrum communication is fast acquisition of spread spectrum signal. For the lack of priori information, code phase and frequency offset are both random quantities, it usually takes a long time in signal acquisition, which would reduce the efficiency of the communication especially for the burst communication. Traditional methods realized spread spectrum signal fast acquisition at the expense of acquisition algorithm complexity and hardware resources cost. This article presents a low cost new code phase and carrier frequency of spread spectrum signal correction method that is easy to implement based on GNSS positioning and timing system. In order to correct the frequency offset and code phase difference, position and time information given by GNSS system are used to build the network-wide time synchronization system and indirect loopback correction system in ground station. At the same time, with the aid of satellite timing, the influence of clock error is eliminated in the way of DDS. With the above measures, the spread spectrum signal fast acquisition could be realized in the network-wide time synchronization system.

With worldwide increased Global Navigation Satellite System (GNSS) receivers, it is possible to obtain the ionospheric total electron content (TEC) and hence monitor the ionosphere with GNSS. Using a thin layer assumption of the ionosphere and dual-frequency Global Positioning System (GPS) observations from 16 geomagnetically quiet days in four seasons of 2006, this paper adopts the spherical harmonic model to fit TEC and investigates the effects of two network constitutions on global TEC derivation, one with 275 GPS receivers and the other with 125 GPS receivers. The results show that the data can be well fitted for both network constitutions. The derived TECs are consistent with each other for four seasons. This is especially true for TECs at low- and mid-latitude. The derived satellite and receiver biases are stable during the year. The standard deviation of the satellite and the receiver biases are less than 0.5 and 3 ns, respectively.

The technology can be used to measure the wind and the height of the sea based on the GNSS-R, It can be complementary to the other advantages of sea measurements, has more advantages than other methods when it can be used to constitute constellation. When to deal with the environments of the sea surface, only need is to install the receiver, so compared to traditional means of remote sensing, GNSS-R technology reduce costs, weight, and the power, at the same time, the technology can improve the resolution and accuracy, It can be used to the new way at remote sensing. This paper designs a new GNSS-R receiver based on the Digital beam forming (DBF), the receiver through the dbf to synthesis the receive signal. The receiver has 31 dbf channels, so it can complete the synthesis a plurality of different direction’s signal at the same time. In order to effectively improve the detection area, the receiver can achieve the angle scanning between the fixed angle and the dynamic angle. In order to test the receiver, we did an experiment by using the plane on November 3, 2015 at Bohai Bay, flying height about 1200 meters, in the experiment, we successfully captured the reflected signals at the high altitude (1.2 km) dynamic scenes, after that we got the delay-doppler mapping through to deal with the reflected signals. By calculating the phase difference between the reflection channel’s DDM and direct access, we got the high information of the receiver, after that we compared the high information that can be got through the receiver, the answer showed that the deviation is less than 4 m.

Compared with the traditional radio atmospheric detection and radar detection, GNSS occultation technique provides a powerful tool for atmospheric detection, the GNSS occultation technique which has the characteristics of without calibration, all-weather, high precision, high vertical resolution, and global uniform coverage. The GNSS occultation technique based on the atmosphere GPS/LEO radio occultation, GPS satellite radio signal is obscured by Earth’s atmosphere, GPS satellite radio signal cutting the Earth’s atmosphere and ionosphere sectional, then the radio signal refracted before reach LEO satellites. The received GPS signal contains information of the Earth’s atmosphere and ionosphere. We can get atmospheric and ionosphere electron density profile, the total electron content of the ionosphere and atmospheric bending angle profiles, index of refraction, temperature and barometric pressure through the relevant atmospheric inversion model. This paper introduces GPS radio occultation atmospheric detection technology based on mountain-based experimental verification, test is located at Wuling Mountain Peak of Yanshan Mountains (located in Chengde in Hebei Province, 117.48°E, 40.60°N, ~2118 m), and made a detailed presentation for signal capture, signal track, and data quality. Different from prediction algorithm of spaceborne occultation, the test used the mountain-based occultation prediction based on the fixed position, getting the forecast results of a week about occultation event. Because of mountain conditions and other factors, occultation signal capture is different because of different azimuths, and made a comparison between different azimuths making a analysis against signal to noise ratio (SNR), the consistency between the Carrier phase and the pseudorange, the reason of signal loss of lock. In order to verify the accuracy of GPS radio atmospheric occultation, this article compares the refractive index profile obtained by inversion with meteorological data, test results were better than 5 %.

Different from other GNSS navigation systems, the constellation of BD navigation system consists of GEO, MEO, and IGSO satellites which is the characteristic of BD. The altitude of GEO orbit is higher than that of MEO. Therefore, the ephemeris and ionosphere delay errors are more dependent in the paths from GEO satellites to two users involved in time comparison. Therefore, the results of common view time transfer based on GEO satellites are better than that of MEO. A method of changing the generation of UTC time parameters is proposed which makes full use of the advantages of GEO satellites in time transfer. The time difference between system time of navigation system and UTC(K) is monitored by user terminal which referenced with a ultrastable frequency signal. The UTC time parameters are generated based on these time differences. Users with the new UTC time parameters not only can get the time difference between their local time and UTC(K), but also can farther eliminate the errors in one-way timing method. Without aggravating the burden of users, the precision of this method is equivalent to that of common view time transfer which is superior to the existed GPS and BD one-way timing method.

The GNSS observations quality can be affected by the environment around the station. Using the signal-to-noise ratios to correct the observation influenced by multipath effect has attracted attention of many scholars. Meanwhile, using GNSS-MR technology based on SNR information to study environmental changes around the station has become a new research subject. And that makes the GNSS active in the field of remote sensing. First, the relationship between GPS multipath and SNR is analyzed in this paper. Then, based on the SNR and the signal amplitude variation, the basic principle of GPS-MR technology is given. GPS observation data in P351 and SNOTEL station snow data are used to evaluate the effectiveness of the algorithm. Also, satellite reflection point trajectory and satellite selection of snow depth detection are further analyzed. The experimental results show that: GPS-MR can be used to measure the snow depth, and its detection precision is 0.08 m. GPS-MR technology not only can make full use of multipath effect, but also provides a development space for GPS technology using in the surface environment monitoring.

The paper proposed the mathematical model, the processing method, and the basic process for the kinematic differential positioning. First, the single epoch is used for initializing, and the wide-lane ambiguity is searched and fixed to calculate the basic ambiguity during this process. Then, the baseline solution is calculated by the least squares method, and gross error is processed by using robust estimation. Moreover, the residual error is considered to correct the basic ambiguity. Finally, epoch is updated. If there is a situation that new satellite appears or cycle slip happens, the corresponding basic ambiguity is needed to be calculated again, otherwise the basic ambiguity is only transmitted. An example, in which 20 Hz GNSS data is sampled by V-Surs I vehicle-borne three-dimensional mobile surveying system, is presented in this paper. The method mentioned above is used to calculate this data and compare it with the results calculated by the GNSS/INS tightly coupled of Inertial Explorer 8.60 software. The experimental results demonstrate that the method has high stability and accuracy in the medium-short baseline, and RMS in the north direction is less than 2 cm, RMS in east direction is less than 3 cm, and RMS in the up direction is less than 5 cm.

Based on un-differenced model of clock estimation, the mathematic model of real-time clock estimation influenced by orbit error is derived, and then the estimation accuracy of BDS real-time clock and real-time positioning accuracy are analyzed. The results show that real-time BDS clock accuracy achieves 0.30 ns using the rapid orbit product and the corresponding 2-D and 3-D real-time positioning accuracy are 0.36 and 0.48 m, respectively. With 0.1 and 0.2 m orbit error influenced, the decreased accuracy of real-time clock estimation is 0.05 and 0.14 ns, and the decreased positioning accuracy is 0.057 and 0.154 m, respectively.

This document took the long sequence of IGS ionospheric VTEC (vertical total electron content unit) products as original data, based on the theory research of various abnormally detection methods, we could select the optimal method to process VTEC products, combined with earthquake cases of which the magnitude greater than Ms5.0 in global range from 2003 to the present. According to the principle of mathematical statistics, we found the relationship between the abnormal of ionosphere and the factors of earthquakes. Through calculating the correlation coefficient and the single factor variance analysis between earthquake factors and the ionosphere anomalies, we not only confirmed that the earthquake has an effect on ionosphere anomalies, but also proved the conclusion that the magnitude has the positive correlation with the positive ionosphere anomalies, and under the condition of single factor analysis, we confirmed that the magnitude made a significant impact on the ionosphere anomalies before the earthquake happened.

With the development of Global Navigation Satellite System (GNSS), there is an increase in the number of visible satellite in navigation and positioning. Calculating all visible satellite not only makes the hardware design of the receiver harder, but also can’t guarantee to improve the accuracy of the positioning results, so it is significant to take a certain satellite selection algorithm to the visible satellites optimization. The traditional optimal satellite selection algorithm is complicated, and it also influences the real-time performance of the navigation and positioning. The subsequent improved satellite selection algorithm has effectively enhanced in robustness, accuracy and real-time. The satellite selection algorithm by using Generalized Regression Neural Network (GRNN) to predict GDOP is proposed. The simulation results showed that the algorithm has improved in robustness, accuracy and real-time, and it has certain exploring value for the GNSS satellite selection algorithm with machine learning.

The changes of the Earth rotation, the plates’ movement and the environment of observation can cause the point shift in the GPS network, even if the observation period is a month, the displacement of the two times cannot be ignored. In this paper, take the terrestrial network station and CORS station network in Sichuan province as an example, using the method of limit error ellipse, the horizontal direction of the station is compared and analyzed. And using the stability of the station to indicate the degree of displacement, so as to identify the stability of the fixed point and unstable fixed point; at the same time, the stability of the elevation direction of the station is analyzed by the method of mathematical statistics. It provides a theoretical basis for the analysis of the stability of the network and a reference basis for the selection of the stability of the station to do a permanent reference station.

The polynomial fitting method is used widely to detect cycle slips of carrier phases of GNSS for its easily computer programming and simple algorithm. But, this method is influenced by the observation errors and sampling rates. In this contribution, the polynomial fitting method and the Newton interpolation method are combined to solve those influences. In this paper, we introduce the new method theory and its mathematical model. Finally a test is taken to prove the reliable of the new method. The result shows that the new method does well in cycle-slips detection, and it reduces the calculation amount.

According to nonlinear and nonstationary characteristics of BeiDou satellite clock bias time series, this paper proposed a method using the wavelet neural network (WNN) based on the first-order difference of adjacent epoch to predict the satellite clock bias. Experimental data with sampling interval of 15 min rapid and ultra-rapid satellite clock bias provided by Wuhan University is used to test the validation of the method. The results show that the forecast precision of 6 h for BeiDou satellite can reach 1–2 ns, and the 24 h can reach 2–4.6 ns using the proposed method. The test results also show that the accuracy and stability of the model prediction can be improved greatly using the proposed method compared to the traditional gray model and quadratic polynomial model.

For the tight integration of GPS and the strong-motion records, in order to obtain high-precision co-seismic waves, the precise separation of the moving state and the baseline shift is much important and also difficult for the data solution. In this paper, the experienced CA/CV models and improved CA/CV models are analyzed, and some meaningful conclusions are got from the results comparison of different validations.

Recently, unmanned aerial vehicle (UAV) technology has been growing rapidly and widely used in civil applications, such as aerial mapping, precise agriculture, power line patrolling. However, most of high precision position and orientation systems (POS) are still heavy and expensive, so they are still unpractical to be equipped on UAV. In this study, we investigated the feasibility of providing precise navigation and positioning service for UAV with single frequency GPS/BDS receiver. The challenges of precise positioning for UAV with low cost receivers are threefold: (1) signal captured with low cost receivers and antennas has poorer quality and interference immunity. (2) UAV moves fast and flexible. (3) UAV navigation requires real time and high reliable positioning solution. GPS-based single frequency can provide centimeter accuracy positioning in friendly environments, while its availability and reliability is difficult to meet the requirement. In this study, we introduced GPS/BDS combined RTK positioning, which increases the redundancy number and improved the precision and reliability of float solution. Meanwhile, we analyzed the signal and antenna gain characteristics of low cost receiver and antenna, and established a refined stochastic model for GPS and BDS observations. We also made use of the Doppler observations to improve the kinematic model and quality control, which significantly improves the success rate of carrier phase ambiguity resolution in single frequency RTK case. In order to validate the performance of our algorithm, we carried out in-flight tests with Tersus single frequency GPS/BDS receiver and analyzed the test results. The results indicate that our RTK algorithm can improve the fix rate of ambiguity resolution from 36 % to around 60 % in challenging environments. We also validated that GPS/BDS RTK has better availability and reliability than GPS stand-alone RTK.

BeiDou Navigation Satellite System Reflectometry (BDS-R) is an emerging area of BeiDou (BD) applications that use reflected signals in microwave remote sensing. Soil moisture (SM) estimation by using the BD GEO signals are more favorable than the GPS signals, since the fixed elevation angle, the fixed height of orbit, the fixed satellite coverage. In this study, the principle of SM measuring by BDS-R is described. First the signal-to-noise ratio (SNR) data of BD directed and reflected signals are collected though the right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) antenna, then the SNR data is extracted and the reflection coefficient is computed, at last, the variance of the reflection coefficient is calculated and the empirical model between in situ SM and the variance is established. One month of experimental data are collected at BaoXie, WuHan, and analyzed for further inversion. Experimental results show that the variance of reflection coefficient increases when SM increases and decreases when SM decreases. We can conclude that using BDS-R to retrieve SM is feasible, which will expand the application field of the BD system.

Using Global Navigation Satellite System (GNSS) signals of BeiDou navigation satellite system (BDS) and global position system (GPS) for soil moisture estimation is an emerging technology in microwave remote sensing since soil moisture is an important index in regional water cycle research. Based on the developed forward multipath model, this study first investigates the feasibility of soil moisture estimation based on GNSS interference signals; then compares the difference between the Signal-to-Ratio (SNR) data and the signal strength (sn_rnx) data from GPS. After that, this paper analyzes the experimental data from BDS receivers and CORS stations. The analyzed results show that both fitted phase of BDS SNR data and GPS sn_rnx data will increase when the soil moisture increases, and the phase will decrease when soil moisture decreases, and the method of using sn_rnx data can obtain the change trend of soil moisture and can be used as an alternative to solve the problem that the SNR data is unavailable in many GNSS data sets.

The aerospace TT&C system plays an important role in tracking spacecraft, and it is necessary for maintaining its good performance and precision. This paper focuses on the application of BeiDou satellite navigation system (BDS) in the precision verification of aerospace TT&C equipment, an algorithm model of the BDS kinematic relative positioning is proposed, and the feasibility of this algorithm is verified by an actual flight experiment. Based on above, the BDS precision verification system is constructed, and the composition, function, information interaction, and working principle of the system are introduced, several methods are studied such as kinematic relative positioning data processing method with BDS, data processing method for TT&C equipment and comparison analysis method, then a complete data processing flow is formed. Based on this system, the precision verification experiment of a TT& C equipment is completed, and various index of precision is obtained, which plays an important role in analyzing the performance of the aerospace TT&C equipment.

With the development of large-scale continuous operation reference stations (CORS) network technology, the rapid solution of massive data via network has become a hot research topic. When taking the monitoring of the crustal movements and the solution of the earth model parameters as examples, the existing data processing and analysis modes exhibit the low processing efficiency. In this study, a data processing framework for large-scale CORS network is proposed based on cloud computing. An elastic compute service with distributed storage and parallel computing ability is built to implement the high-efficiency solution of the large-scale CORS network data, according to the temporal–spatial characteristic of the CORS data. The results show that the accuracy obtained by the proposed method is equivalent to that of the Gamit/Globk solution. However, the efficiency of the proposed method is obviously superior to the current processing method. For the test of CORS data from 10 stations over 577 days, the efficiency of this method is increased by 25.74 % compared with the Gamit/Globk. With the increase of the CORS data and the number of nodes, the efficiency of proposed method will be further increased. Finally, this study demonstrates that the data processing framework greatly improves the efficiency in processing the large-scale CORS network data. Also, it provides a high-efficiency data solution for the applications in view of the large-scale CORS network data, such as the crustal movements, crustal motion and deformation, instantaneous global plate motion, the earthquake cycle, coseismic slip distribution, and the interpolate fault slip.

When the receiver cannot demodulate satellite signal transmission time, positioning can be completed with a combination of code phase measurement and auxiliary information, that is, coarse time navigation (CTN). Assistant information includes ephemeris, priori position, and coarse signal transmission time. For the GPS systems, requirement of the position and time precision is 100 km and 1 min. This paper attempts to determine the allowed priori position and coarse time error range of BDS and has realized the GPS/BDS coarse time navigation algorithm and carried out experimental verification using the measured data of IGS CUT0 station. The results show that BDS, GPS, and BDS/GPS coarse time navigation positioning precision is equivalent to their pseudorange positioning precision. Dual system CTN can effectively improve positioning precision, which is better than the precision of single system pseudorange positioning or coarse time navigation. Conclusion is that BDS/GPS coarse time navigation is an effective method without pseudorange and that dual system navigation is easier to receive enough visible satellites.

Space navigation users of GNSS can be classified into four categories: low orbit users, medium orbit users, high orbit users, and deep space users. The GNSS space navigation capability can be analyzed by visibility, GDOP, and received EIRP. The transmit antenna pattern and space receiver antenna orientation are important factors which should be considered carefully. In this paper the navigation requirements are put forward, respectively, for different types of space user. And the related factors are studied theoretically. At last, the navigation capability for space users of one MEO constellation is simulated with “satellite navigation mission analysis simulator (SNMAS).” The simulation illustrates that: the constellation can provide almost the same navigation service for the low orbit users and the land users; the “continuous positioning” requirement of medium orbit users can be reached; the “intermittent positioning” and “continuous timing” requirement of high orbit users can also be realized; but the “continuous timing” requirement of deep space users cannot be realized such as lunar orbit users.

Location-Based Service (LBS) has been an indispensable part of our daily life. However, LBS may cause the risk of revealing the location privacy of the users, and that could be abused illegally. To defend users’ location privacy against the threats, we propose a location information authentication system with a revised algorithm based on a trusted third-party architecture. The improved algorithm is built upon the so-called CliqueCloak theorem which is supposed to prevent the privacy disclose caused by side information. Our contribution lies in developing a revised top location algorithm to reprocess the points failing in K-anonymity process. Using the set of road network top locations on the map, we could assign those points a new anonymous area. Our experiments show that the improved personalized k-anonymity location information authentication algorithm outperforms the classical one in terms of the success rate and the computing efficiency.

In indoor environments, GNSS signals endure serious attenuation, hence a GNSS receiver could not output accurate, reliable positioning solutions continuously. Pseudolite positioning system was proposed as a suitable alternative solution for indoor positioning applications. In this research, a new indoor pseudolite positioning system based on carrier phase interferometry technique is presented. This pseudolite-based positioning system can achieve decimeter accuracy without the support of a base station, and without the need of synchronization between pseudolites. In addition, in the proposed new positioning system the integer ambiguity resolution is unnecessary as well. In this pseudolite system, the main part of interferometric measurement is a dual-antenna software receiver. By using the principle of interferometric measurement, dual-antenna software receiver could deduce the spatial relationship between the dual-antenna and pseudolites. As a result, dual-antenna’s position can be determined uniquely. Experiment results demonstrate that a horizontal positioning accuracy of decimeter-level accuracy can be obtained.

With the deepening development of mobile Internet technology and Global Navigation Satellite System (GNSS), realizing high-precision positioning and navigation on mobile intelligent terminals is not only an important way to achieve the urban high-precision location-based services (LBS) in the future, but is also one of the development trends and major application fields of the satellite navigation industry. Although those mobile intelligent terminals such as smart phones basically have integrated a GNSS module, their positioning accuracies are generally low which cannot meet the requirements of high-precision location-based services. In this work, a system design scheme for realizing high-precision location-based services was studied and proposed, and a set of BDS/GNSS real-time high-precision positioning software for mobile intelligent terminals is developed based on Android platform. By collecting the observation data stream from an external GNSS module through the built-in Bluetooth module on those intelligent devices and receiving the differential correction data from a nearby reference station via 3G/4G or Wi-Fi wireless network, respectively, users’ high-precision position then can be calculated in real-time by the software, and the positioning result will be displayed on Google maps simultaneously. At present, this software supports real-time single point positioning and real-time pseudorange differential positioning for BDS/GPS/GLONASS standalone and combined system. The experimental results of combined BDS/GPS/GLONASS real-time positioning show that the accuracies of single point positioning in horizontal and vertical are better than 2.5 and 3.5 m, respectively, and the accuracies of real-time differential positioning in horizontal and vertical are better than 0.5 and 1.0 m, respectively. As a consequence, this contribution can provide some technical references for the realization of urban high-precision location-based services.

In order to solve the problem that traditional eigenvalue analysis of time domain and frequency domain cannot classify pedestrian’s motion state correctly in pedestrian navigation because of the changing of stride frequency and length, etc., a method for motion state analysis in combination with time domain characteristics and entropy of sEMG was presented. This method analyzed the complexity and amplitude of pedestrian’s motion state, estimated the stride frequency, and classified four movement state include walking, running, upstairs, and downstairs according to variation feature of sEMG. The experimental results show that the average classification accuracy went up at least by 8.25 % with presented method, it gets more reliable and stronger anti-interference capacity compared with the characteristics of time domain.

To overcome the negative influences of exceptional fiber optic gyro (FOG) signal on the performances of INS/GPS integrated navigation system, a FOG signal de-noising method in the time–frequency domain is proposed based on the empirical mode decomposition and Allan variance (EMDAV) in this paper. Initially, the FOG output signal is decomposed with empirical mode decomposition (EMD), and then the decomposed signal is analyzed by Allan variance. The noise is removed based on the error characteristics analysis of FOG signal in time–frequency domain. Real FOG data is processed by the de-noising method based on EMDAV, and the results show that, the mean and variance of the signal de-noised by proposed method can be reduced with 2 orders of magnitude than the wavelet method. The experiment of INS/GPS integrated navigation system under GPS failure indicates that, DEMAV can improve the navigation accuracy effectively.

A method of X-ray pulsar-based navigation for satellites constellation in Halo orbit is given in this article. The dynamics of libration point orbits offer many opportunities for flexible, low-energy trajectories, and missions around libration points are arising. Autonomous navigation is necessary for spacecraft autonomy in libration point, as well as significantly benefits China’s deep space missions. In this paper, the state equation is established according to the dynamic characteristic in the libration point orbit. The difference of pulse arrival time to different satellites can be regarded as the measurements in the measurement equation. Unscented Kalman filter is applied to estimate the state of the system. Simulations demonstrate that this method is feasible for autonomous navigation for satellites constellation in the Sun–Earth libration point orbit. Comparing X-ray pulsar-based method with the traditional inter-satellite links navigation principle, satellites constellation rotation can be solved. Combining inter-satellite links and pulsar measurements in the UKF filter, the state of the system can be estimated more precisely and in a more quick way.

A map-based pedestrian navigation method is presented in this research, integrating indoor map information and MEMS-based inertial sensors to enhance the performance of pedestrian indoor navigation. This paper demonstrates how Map Matching (MM) and Map Aiding (MA) methods constrain the navigation solution through an auxiliary particle filter. Previous studies examined each method individually, but the combination provides a more accurate position estimation. Additionally, this research introduces a novel cascade structure filter algorithm to reduce the computational burden and improve the estimation speed of APF by decreasing the update frequency of APF. The accuracy and availability of the proposed algorithm are tested and validated by performing experiments in various practical scenarios.

In order to improve the accuracy and robustness of targets tracking and positioning, this paper proposes a particle filter algorithm based on multi-feature fusion. According to the diversity of character information, a multi-feature fusion strategy based on color, texture, and edge character has been developed, which can realize the comprehensive utilization of various visual features information. A feature criterion function has been addressed to the weighted strategy of multi-feature fusion, which can adjust adaptively the weight of feature and enhance the reliability of target tracking. Combined with binocular stereo vision technology, this algorithm can locate the target by calculating the geometrical relationship between the correspondence pixel points and spatial points. The test results show that the algorithm can realize the target tracking and positioning more accurately.

In view of the present problems of BDS receiver in the indoor weak signal environments faced with strong signal attenuation, the NLOS propagation, cross-correlation effects, the A-BDS coarse-time navigation, and RAIM algorithm to solve the problems of indoor positioning and the use of BDS data to verify the reliability of above-mentioned method are proposed in this paper. The experiment shows that the coarse-time navigation algorithm is able to provide consecutive and reliable positioning results and also it can be used in the weak signal environments. RAIM algorithm based on the combination of FDE can increase the availability of the positioning result, this, to some extent, solve the problems of NLOS propagation and cross-correlation effects existing in indoor satellite signals.

Based on an analysis of the connotation of smart tourism and the perspective of smart scenic construction, a concept of BeiDou Satellite Navigation System (BDS) smart tourism is proposed. Later on, some related key issues are discussed such as system architecture, wide-area continuous coverage positioning network technology, and wide-area continuous coverage communication network technology. Taking Jiuzhai Valley as experimental construction spot, the BDS smart scenic location-based service (LBS) system was developed and deployed. With such technical features such as both way, teamwork, information push, and remote interaction, this system improves the tourist LBS, fine management, and unexpected event handling capacity of the resort. Finally, the paper recommends the BDS smart tourism LBS system to become an important part of the one belt and one road (OBOR) strategy, for it is believed that this system will significantly speeds up the intelligent tourism construction of the neighboring countries, promote the cultural exchange and cooperation, and drives up the economic development of the concerned regions.

Based on the correlation coefficient between the time series of the GPS network, extracting the common model error (CME) using principal component analysis (PCA) in Crustal Movement Observation Network of China (CMONOC). This method does not need the assumption of spatially uniform distribution like stacking. Compared with the traditional regional stacking (RS), correlation weighted regional stacking (CWRS), and traditional PCA, this method extracts CME more accurately and reduces the influence of local effects during extracting the CME.

Sidereal filtering is effective to mitigate multipath errors from observations or coordinates by taking advantage of the sidereal repeatability of GPS multipath signals. However, the characteristics of BDS multipath effect are different from that of GPS because the constellation and orbit of BDS are more complicated than that of GPS. According to the repeatability of BDS multipath signals, the multipath hemispherical map (MHM) is established for each satellite pair based on double difference residuals, and then the validity of the model is tested using real field observation data. The results show that the BDS MHM can reduce the root mean square (RMS) of double difference residuals by 83.6 % on average and improve the coordinate accuracy by 20.0, 52.2, and 16.5 % in E, N, and U directions, respectively. While observation sidereal filtering method improves the coordinate accuracy by 17.5, 50.0, and 13.0 %, and coordinate sidereal filtering method only improves the coordinate accuracy by 12.5, 42.2, and 7.8 % since it does not consider the repeat periods of MEO satellites multipath signals, which are about 7 days. Compared to the sidereal filtering methods, MHM is not only more effective to multipath mitigation, but also easier to implement in real-time applications since it can avoid calculating the accurate repeat period of multipath signals for each satellite.

In recent years, indoor space of human activities has been more and more huge and complex. Point of interest (POI) has been increasingly abundant. There is an intense trend of positioning and navigation in parking lot, shopping mall, and airport. Meanwhile, it is a matter for computer to recognize the specific position in the room on exact-marketing, intelligent manufacturing, robot and no one care etc. These requirements bring in a huge opportunity for IPS (indoor positioning system). Although GNSS has made great success in the aspect of positioning in recent years, traditional positioning (satellite positioning, base station location) can not be able to meet the indoor positioning because of technical restriction. At present, using Wi-Fi or Bluetooth beacon positioning technology that it acquires user’s position by detecting the RSSI power and matching beacon position faces huge challenges on the account of laying a number of beacon station on Wi-Fi or bluetooth positioning system, poor stability in the results of positioning and the terrible noise interference. The paper comes up with a positioning system of BeiDou compatible system, which is prominent to reduce the change of intelligent mobile terminal and the complexity of infrastructure construction on indoor positioning, realizes indoor–outdoor positioning compatibility and seamless connection. The core of the system is high performance multi-output satellite navigation signal simulator. Every output port of the simulator is provided with independent output function of single satellite signal and produces the pseudolite signal that can be compatible with BeiDou system air interface and design special broadcast content. The receiver combines carrier-phase smoothing with different positioning technology and achieves indoor–outdoor seamless positioning by BeiDou positioning terminal. This paper builds BeiDou compatible indoor–outdoor positioning testing system and provides the test data and conclusion by test evaluation.

RF signal of traditional real road test system for BDS user terminal is usually unrepeatable while the system is complex and expensive. In this paper, an economic and signal-replicable BDS user terminal test system, constructed with RF signal record and playback apparatus, is described and tested. Compared with commercial satellite navigation signal simulators, experiment results show that the RF signal provided by record and playback apparatus has a maximum carrier-to-noise ratio attenuation of 0.8 dB, which is similar to that of signal simulators. However, the latter device is able to provide much more critical and useful live noises of the ambient. In addition, to characterize the test system, two kinds of test scenario (suburban road and city canyon) are proposed, and experimental data demonstrate a high positioning accuracy (<17.04 m) and usability (>87 %) performance of BDS user terminals under replayed signals.

Service availability for accuracy is a basic element in the performance frame of the GNSS services. In the system designing phase, service availability is a key link to the satellite constellation and maintenance strategy, the distribution of internal reliability performance, and the decision of service accuracy. In the system operation monitoring phase, service availability is one of the emphases of system service performance assessment and evaluation. In this paper, the understanding for the concept of service availability in the field of satellite navigation is introduced first. Then, some key problems in the design of satellite navigation service availability are studied, a calculation formula of service availability is proposed based on multiple constraints such as single satellite availability, ranging error and user operating conditions, and the accuracy threshold for the service availability is established which is different from the GPS SPS. Finally, according to two configuration alternatives of the BeiDou global constellation, simulation analysis of the service availability of the Asia-Pacific region is made, pointing out the difference between the two alternatives, providing a reference for the future BeiDou global system optimization.

GNSS timing is the process for users to obtain the UTC time from the satellite navigation signal. At present, each GNSS has the timing function, but timing performance characterization of different navigation systems is not unified as well as the published data not comparable, which makes the users great inconvenience. According to the users’ using characteristics, the paper proposes the conception and method to test the bias between UTC broadcasted by the satellites and actual UTC, which studies the timing testing methods of single satellite and multiple satellites, and referring to the timing performance of GPS, GLONASS, and BDS we develop the integrated testing and evaluation experiments. The result shows GPS timing error is better than 20 ns, and GLONASS timing performance is less than GPS with timing error relatively higher fluctuation; compared with GPS and GLONASS, timing evaluation of BDS has still a certain distance that sometimes the maximum timing error can be up to 120 ns, thus from the users’ perspective the UTC precision obtained by the BeiDou satellites is less than GPS and GLONASS.

At present, the Galileo in-orbit satellites include four in-orbit validation (IOV) satellites and eight full operational capability (FOC) satellites. The accuracy of Galileo positioning is better than 2 m. Thirty FOC satellites are expected to be launched completely by 2019, and a complete constellation of full operational capability will be achieved by the time. The quality of Galileo satellite clock affects the performance of navigation and reliability. Based on this, a solution of satellite clock assessment is given, the standard time and frequency signal of National time service center of Chinese Academy of Sciences are taken as references. The performance of all Galileo in-orbit satellites clocks is assessed by receiving the signal in space and using the way of dual-frequency ionosphere-free combination, which includes frequency deviation, frequency drift, frequency stability, and the consistency of the frequency stability over time. At the same time, the uncertainty of relative frequency, frequency stability, and time offset of Galileo satellites clocks is analyzed. The evaluation results show that the orbit satellite clock frequency stability is (τ = 60 s and τ = 300 s) at e−13 level, the uncertainty of frequency stability is in the order of e−14, and the stability is consistent over time. When the satellite clock time is corrected to the Galileo system time (GST), the time offset of GST relative to UTC (NTSC) is between −40 and −70 ns, and the satellite clock stability after clock correction is slightly improved. The uncertainty of measurement of system time offset is 3.37 ns. Research methods and achievements of this paper can be the significant references with respect to Galileo stand-alone positioning, multi-GNSS combination positioning, integrity monitoring, the Galileo system time interoperability, etc.

Improving the autonomous operation ability has become a main goal of satellite navigation system in the new century. The technology to apply inter-satellite link (ISL) to perform high precision measuring between satellites is a technology to implementing autonomous operation of navigation satellite constellation, and Dual-One-Way Ranging (DOWR) of Ka band is an effective way to carry out high precision measurement between satellites. Ka DOWR data of satellite-ground could be achieved by setting up the measuring link between orbiting satellite and pseudolite on the ground, analyzing precision it combined with precision analysis of troposphere and ionosphere correcting models, we can further infer the ranging precision of satellite–satellite. In order to evaluate the precision of satellite–ground Ka DOWR data, a method of using SLR data as exterior checking for comparison is proposed. The raw data of Ka and SLR contain environment effect, and their measuring time and spatial reference do not coincide. To achieve high precision evaluation of Ka DOWR data by SLR, it is needed to go through the environment error correction, time, and spatial reference formalization and some other steps. The errors in the steps will have impact on the final precision evaluation result. In order to verify the feasibility of this evaluation method, this paper starts from the principal of Ka DOWR and SLR, then analyzes the error sources that impact the evaluation result and expounds the principle and process of this evaluation method. By setting up the ground test simulation platform of ISL, the Ka satellite-ground DOWR and SLR data are obtained and analyzed. The simulation results show that the evaluation precision of this proposed method is in the magnitude of centimeters, which can provide reference for the analysis of the satellite–ground test data of ISL.

BeiDou Navigation Satellite System (BDS) can provide regional services at present. Its ground segments are mostly within the territory of china which leads to the lack of whole arc monitoring for some satellites. In order to reflect the influence of BDS’s mixed constellation (GEO + IGSO + MEO) and the exploration of broadcast ephemeris due to lack of whole arc monitoring, the paper conducted the URE evaluation of BDS constellation based on the constrained condition of Age of Data (AOD). The paper got the URE features of single satellite by analyzing the probability statistics characteristics under AOD, and then evaluated the constellation’s URE based on the weight conducted from the above. The verification of the method was done by the real data.

Currently, the test of the GNSS/INS integrated navigation system is primarily a real testing in the vehicle or a computer software simulation test. There are defects of high cost, difficult to repeat the testing scenario, and other issues in the former and the test not comprehensive enough in the latter. This paper proposes a semi-hardware type simulation and testing platform design, which is based on GNSS simulator, high-precision three-axis turntable and master control system, and builds a semi-hardware test platform. The platform has a flexible programmable configuration and repeatable test scenarios and the platform also has good stability and scalability. Based on iFEN NavX-NCS satellite navigation simulator and SGT320E precision three-axis turntable,we built semi-physical simulation test platform for the design implementation and verification scheme. The real test results of NovAtel’s SPAN-SE commercial GNSS/INS navigation system verify the availability, effectiveness, and stability of the platform.

Geomagnetic storm activity will cause a certain degree of disturbance on the global ionosphere; ionospheric model error which is one of the main error sources of satellite navigation system will affect the service performance of the satellite navigation system. In order to analyze the influence of geomagnetic storms on the satellite navigation system, especially the Beidou satellite navigation system, this paper takes a strongly storm which took place from March 9th, 2015 to March 21st as an example, respectively, analyze BDS and GPS ionospheric delay precision when ionosphere is quiet or disturbed. Further, it makes contrast the difference of positioning accuracy between BDS and GPS when ionopheric disturbance happened in March, 2015. The results show that BDS and GPS ionopheric model are affected by the storm, both the ionopheric model correction rate and service performance are decreased.

With the continuous promotion of Beidou satellite navigation applications, improving the navigation terminal performance is a hot issue under city environment because of its wide application and complex signal propagation. Based on received Beidou satellite signal power shadowing under different environments in city application, the paper proposed a statistical Markov model with three states: line-of-sight (LOS), shadow block, and using a combination of mixture Gaussian functions to approximate the distribution of signal variations. Channel parameters are evaluated from the experimental data in shanghai and utilized to verify the proposed simulated model. Signal waveforms and probability density functions show proposed model close agreement with measurements.

With the wide application of multiplexing technology in navigation satellite system, the traditional processing method for one channel signal is no longer suitable for the analysis of composite baseband waveform, which requires signal separation. However, there is a lack of effective navigation signal separation methods currently. First, on the basis of the traditional average algorithm, a signal separation algorithm for signal quality assessment is proposed, and the mathematical model of the algorithm is presented. Utilizing the random of the data bits modulated on different channels, the algorithm can achieve the signal separation by accumulating the multiple code epochs which are selected from the composite signal conditionally. Second, the effect of the carrier phase error, code phase error, and Doppler shift on the separated signal is analyzed. What is more, the difference between the waveforms of the ideal signal and the separated signal is studied, and the estimation error of the separated signal waveform parameters is provided. Finally, the simulated and measured Galileo E1 signals are separated. The baseband waveforms of the composite signal and one channel signal are compared, and the eye diagrams of signal before and after separation are analyzed. The above theoretical analysis and experimental results show that the algorithm is reliable and effective.

Under ideal conditions, the correlation peak of navigation signals emitted by the navigation satellites is completely symmetrical, and the pseudoranges obtained by the receiver to different satellites are consistent. However, live signals differ from this ideal due to characteristic difference of satellites’ navigation overload, the troposphere and the ionosphere, multipath effects and other factors, the signals emitted by each satellite reaching the ground show nonideal characteristics and differences on each other resulting in the biases of pseudorange measured by receiver to the different satellites. In this paper, based on the signal correlation domain analysis and observations data domain analysis, we analyzed GNSS navigation signals, respectively with navigation signal quality monitoring equipment and monitoring receiver. The analysis results show that the pseudorange between different satellite navigation signals occur 2–3 ns biases, and the ideality and inconsistency of navigation signals emitted by different satellites might be the main factor of pseudorange biases, and receiver channel design, loop design, and other factors can also affect pseudorange bias value.

Positioning receivers are required to be capable of receiving weak signals to satisfy indoor applications. When searching weak signals, the receiver may unsuccessfully be acquired due to the noise. This paper is focused on the problem of weak signal acquisition in Time and Code Division-Orthogonal Frequency Division Multiplexing (TC-OFDM) system which is based on the mobile broadcast networks. We provide theoretical analysis of the TC-OFDM signal, and propose a new acquisition algorithm based on coherent/noncoherent integral for weak signal acquisition. This algorithm compensates noncoherent integral loss for considering the effect of decision threshold that caused by noncoherent integral loss, which can increase the relative acquisition peak and achieve weak signal acquisition effectively. The experimental results indicate that the proposed algorithm can significantly improve the TC-OFDM receiver’s ability of weak signal acquisition by 1–3 dB, and reduce the probability of weak signal acquisition leakage.

Satellite navigation receiver would have difficulties in continuous positioning or gets a bad positioning performance in dense urban environment, mostly due to low signal-to-noise-ratio and frequently signal outage. To improve robustness under the challenging environment, a combined BeiDou Satellites System (BDS) and global positioning system (GPS) adaptive vector tracking loop is proposed. An adaptive extended Kalman filter (EKF) based on innovation sequences is employed to tune the tracking loop, and generate navigation solutions. The algorithms are implemented on Matlab software receiver and digital intermediate frequency (IF) signals grabbed by a global navigation satellite system (GNSS) signal sampler under blocked outdoor scenarios are utilized to verify the performance. The tracking and positioning results of vector and scalar tracking loop are compared.

With the development of global navigation satellite system (GNSS), binary offset carrier (BOC) modulation signal has been widely used for GPS and Galileo. However, because of the effect of the subcarrier, the autocorrelation function (ACF) of BOC signal has a main peak and some side peaks. The traditional delay-locked loop (DLL) may be locked on the side peaks of ACF, which causes an extra tracking error. Dual-estimate loop method is an effective unambiguous tracking method, which makes use of two DLLs to track the code phase and the subcarrier phase in BOC signal. However, the multipath effect is not taken into account for dual-estimate loop method. This paper proposes an unambiguous multipath mitigation method, which employs the dual-estimate loop method to solve the tracking ambiguity problem for BOC signal and makes use of double-delta correlator in the subcarrier tracking loop to mitigate the multipath effect. In addition, a bias code delay estimate value is used in the subcarrier tracking loop to enhance the performance on the multipath mitigation. Simulation results demonstrate that the proposed method can provide the same level of tracking performance as the traditional DLL tracking technique in the case of high carrier-to-noise ratio (CNR) and have the excellent performance on the multipath mitigation.

In global navigation satellitesSystem (GNSS) receiver, ionospheric scintillation may lead huge tracking error and frequent cycle clips to the carrier phase tracking loop. When strong scintillation, the phase lock loop (PLL) of receiver may even lose lock. Although the frequency lock loop (FLL) is insensitive to the ionospheric scintillation, the tracking accuracy is poor which is insufficient for most GNSS applications. In this paper, we propose an improved adaptive Kalman filter-based carrier phase locking loop for the scintillated signal tracking. In the loop, the signal amplitude is added in the state vector of the Kalman filter. By calculating the statistic result of the amplitude variance, the amplitude is adaptively estimated. At the same time, the phase discriminator is normalized by the amplitude estimation results. The Kalman filter is redesigned based on the new structure so as to improve the stability of the loop and reduce the effects of amplitude attenuation and phase jitter on the loop. Simulation is carried out based on the ionospheric scintillation data obtained according to the A. J. Stanford model. The results show that the proposed loop can keep working in the continuously moderate and instantaneous strong ionosphere scintillation with less cycle clips.

The update rate of vector tracking loop (VTL) is usually the same as the message rate modulated in navigation signal, and BeiDou satellites broadcast D1 NAV message and D2 NAV message which will lead conflict of update rate for VTL. To solve this problem, a novel VTL based on non-coherent discriminator is proposed and a method to optimize its update interval is also introduced. Analysis and simulation show that for low dynamic user, the update interval can be designed longer than 0.1 s and the complexity of VTL can be reduced largely. If the update interval is 0.3 s, this algorithm can track the signal broadcasted by GEO satellites in steady when C/N0 is lower as 20 dBHz.

Spatial Temporal Adaptive Processing (STAP) nulling algorithms have been widely used in GNSS anti-jamming receivers using multi-element antennas. Traditionally, these algorithms are implemented on hardware due to their high computational complexity. This makes it costly and inconvenient to test and verify different algorithms and parameters. In order to address this issue, a GNSS anti-jamming platform for STAP nulling algorithms is implemented using a software approach. On this platform, raw data from eight element channels can be processed real-time with configurable algorithms and parameters. Weights can be calculated by various methods such as SMI, LMS, and RLS. Plenty of intermediate data can be observed immediately or saved for post analysis. To meet the real-time requirement, a GPU is used as an accelerator and a batched method is adopted in programming. Besides, a software receiver is integrated for anti-jamming performance evaluation. Test results show that this platform has a good performance in both computational efficiency and interference mitigation, making it a promising product in research and prototyping, as well as practical applications such as ground stations.

For detection and identification of GNSS spoofing, this paper proposes to use multi-antenna two-channel direction-finding method and the carrier phase observed quantities that are provided by the receiver to estimate the arrival direction of GNSS signal or spoofing signal, which is then compared with the ephemeris data solved by the receiver. In such a way, it is possible to make high-precision estimation of the arrival direction of spoofing signal. The validity of the proposed algorithm was validated with a simulation test.

Frequency domain antijamming (FDAJ) has been widely adopted by most of the military satellite navigation receivers. It is simple in theory and easy for realization. It can effectively suppress single-tone interference, sweep interference, and narrow band interference with Gaussian distribution. However, FDAJ will result in distortion of navigation signal, while suppressing interference. Previous works about effects of FDAJ on navigation signal have not taken interference spectrum leakage induced by time window shaping. It results in effects of FDAJ on navigation signal which has no relationship with interference power, and violates the practical. Therefore, take narrow band interference with Gaussian distribution as an example. First, its spectrum leakage induced by time window shaping is analyzed. Then, extra FDAJ loss induced by interference leakage is analyzed. Finally, FDAJ theoretical model of effects on effective carrier-to-noise ratio (CN0) and pseudocode tracking variance is derived, taking interference spectrum leakage. Numerical computation show that, effective CN0 and code tracking variance increases with jam-to-noise ratio (JNR), when FDAJ suppresses narrow band interference shaped by time window, different from ideal one (without spectrum leakage). When adopting different time windows, rate of receiver performance deterioration with JNR increases caused by FDAJ is different. When adopting Hamming or Hanning window, the rate is far lower than that of rectangular window.

With the development of GPS spoofer techniques, spoofing signals can be consistent with the authentic signals on direction of arrival (DOA) or pseudorange. The receiver will not be effective for detecting such spoofing signals, when using traditional spoofing detection method based on either DOA or pseudorange. In order to suppress this problem, a method based on the joint weighted sum of squares of errors (WSSE) of DOA and pseudorange for GPS spoofing detection is introduced. This method uses the carrier-phase difference and pseudorange observations to form two equations simultaneously, and adds the residuals of two equations after normalization. According to the joint WSSE, it can test the DOA and pseudorange of arrival signals at the same time. Because of this, it can greatly improve the adaptability to different spoofing scenarios. This paper also gives the process to identify and eliminate spoofing signals in the received signals. In conclusion, the performance between the method based on the joint WSSE of DOA and pseudorange and the traditional method based alone on DOA or pseudorange is compared. The simulation results show that the proposed method is superior to the traditional way both in the adaptability to different spoofing scenarios and the detection performance.

In global navigation satellite systems (GNSS), when the receiver carrier is in the situation of attitude high dynamic, the directions of arrival (DOA) of signal and interference will change rapidly over time. At this point, conventional adaptive anti-jamming algorithms become invalid. In this paper, according to the structure shape of practical attitude high dynamic carrier, the DOAs change of signal and interference in the case of uniform circular array (UCA) are analyzed, and the Capon-Laplace algorithm based on UCA was provided to suppress the interference. The effectiveness of the algorithm is verified by simulation experiments. Through the analysis of attitude high-dynamic parameter, the paper compared the feasibility of the algorithm in different degrees’ attitude high-dynamic circumstances giving a further verification on the effectiveness of the algorithm.

Because Global Positioning System (GPS) is easily interferenced by other signal, this paper designs an anti-jamming GPS vector tracking (or vector lock loop-VLL) receiver, which improve its anti-jamming performance on the tracking loop. The traditional scalar tracking loop (or scalar lock loop-SLL) tracks the satellite independently. There is no information exchange between each channel, which ignores the relationship between the receiver’s navigation (position and velocity) and the tracking loop information (code phase and Doppler frequency). The vector tracking loop take the advantage of this relationship, and combine the navigation filter with tracking loop in a Kalman filter, which improve the receiver’s anti-jamming ability and robustness. The simulation analyzes the influence on the tracking loop whether there has an interference, and this paper gives the comparison of position and velocity error. Finally, the weighted least squares method is used to compare the variance of predicted pseudorange error of the two tracking loops when the power of the interference changed. This paper concluded that the vector tracking loop has better anti-jamming ability.