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Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
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2021, 46(1): 1-6.
doi: 10.12265/j.gnss.2020111601
Abstract:
GNSS multipath signals widely exist in complex navigation and positioning scenarios such as urban canyons. Although the multipath signal interferes GNSS receiver and reduces positioning accuracy, it provides environment information around the receiver. Based on the coupled amplitude delay locked loops algorithm (CADLL) which senses GNSS multipath signals and extracts feature parameters, a particle filter-based reflection plane parameters estimation algorithm is designed and implemented. The algorithm can enhance the receiver's environment perception in the GNSS multipath environment, the corresponding information can be applied to the fields of scene perception, collision avoidance, path planning and positioning augmentation. GNSS multipath signal recording and algorithm testing are carried out in a static environment. The experimental results show that the algorithm can effectively estimate the position parameters of the reflecting plane. The root mean square error (RMSE) of the azimuth angle of the reflection plane is less than 10 degrees, the RMSE of the elevation angle is less than 5 degrees, and the RMSE of the distance is less than 10 meters.
GNSS multipath signals widely exist in complex navigation and positioning scenarios such as urban canyons. Although the multipath signal interferes GNSS receiver and reduces positioning accuracy, it provides environment information around the receiver. Based on the coupled amplitude delay locked loops algorithm (CADLL) which senses GNSS multipath signals and extracts feature parameters, a particle filter-based reflection plane parameters estimation algorithm is designed and implemented. The algorithm can enhance the receiver's environment perception in the GNSS multipath environment, the corresponding information can be applied to the fields of scene perception, collision avoidance, path planning and positioning augmentation. GNSS multipath signal recording and algorithm testing are carried out in a static environment. The experimental results show that the algorithm can effectively estimate the position parameters of the reflecting plane. The root mean square error (RMSE) of the azimuth angle of the reflection plane is less than 10 degrees, the RMSE of the elevation angle is less than 5 degrees, and the RMSE of the distance is less than 10 meters.
2021, 46(1): 7-12.
doi: 10.12265/j.gnss.2020052504
Abstract:
Based on the minimal residual criterion, a relaxtion method is proposed to improve the convergence efficiency of the barycentre method for solving the distance equations. The relaxation factor for adaptive selecting the iterative step of barycentre method is derived by the minimum residual criterion. The proposed method has the advantages of simple iterative format without the matrix inversion and to simplify the procedure without calculating the Hessian matrix. Finally, the novel method is performed to solve the data of GNSS and marine positioning examples to show its performance, and results show the numerical convergence experiments are performed to show the convergence efficiency improvment.
Based on the minimal residual criterion, a relaxtion method is proposed to improve the convergence efficiency of the barycentre method for solving the distance equations. The relaxation factor for adaptive selecting the iterative step of barycentre method is derived by the minimum residual criterion. The proposed method has the advantages of simple iterative format without the matrix inversion and to simplify the procedure without calculating the Hessian matrix. Finally, the novel method is performed to solve the data of GNSS and marine positioning examples to show its performance, and results show the numerical convergence experiments are performed to show the convergence efficiency improvment.
2021, 46(1): 13-19.
doi: 10.12265/j.gnss.2020111301
Abstract:
Wi-Fi channel state information (CSI) contains rich feature information, which enables CSI based fingerprint positioning methods to build higher-dimensional features to improve positioning accuracy. However, the redundant information in the fingerprint features also makes the built-up fingerprint database large in storage, and increasing of the time cost of establishing the positioning model becomes large, and the real-time positioning calculation. In this regard, this paper proposes to use principal component analysis (PCA) method to reduce the dimensionality of the original fingerprint features, and then use the sequential minimal optimization (SMO) algorithm to establish the regression model of the reduced feature and the corresponding position and predict the position. The experimental results show that the algorithm in this paper can effectively overcome the above problems, while the average positioning error is 1.25 m, and the cumulative probability of positioning error within 2 m can reach 97%.
Wi-Fi channel state information (CSI) contains rich feature information, which enables CSI based fingerprint positioning methods to build higher-dimensional features to improve positioning accuracy. However, the redundant information in the fingerprint features also makes the built-up fingerprint database large in storage, and increasing of the time cost of establishing the positioning model becomes large, and the real-time positioning calculation. In this regard, this paper proposes to use principal component analysis (PCA) method to reduce the dimensionality of the original fingerprint features, and then use the sequential minimal optimization (SMO) algorithm to establish the regression model of the reduced feature and the corresponding position and predict the position. The experimental results show that the algorithm in this paper can effectively overcome the above problems, while the average positioning error is 1.25 m, and the cumulative probability of positioning error within 2 m can reach 97%.
Unmanned aerial vehicle realistic 3D modeling accuracy analysis considering control point uniformity
2021, 46(1): 20-27.
doi: 10.12265/j.gnss.2020102801
Abstract:
Unmanned aerial vehicle (UAV) tilt-photography technology has become the mainstream of the construction of three-dimensional real-field models with its advantages of low cost, high efficiency and high precision. The accuracy of the real 3D model is affected by many factors. This study is mainly focused on the point of view of the uniformity of the control point distribution, to explore its impact on the accuracy of the real 3D model, and propose a more general measure of control point uniformity. Two experiments with different numbers of control points are designed, and each experiment contains three different uniformity distribution schemes. Aerial images of the experimental area were obtained by UAV, and six schemes were adopted to participate in model. By analyzing the model accuracy, the results show that: the accuracy of the real 3D model is poorer when the uniformity of the control points is lower, and the elevation accuracy is worse than the plane accuracy. Increasing the uniformity of the control points will improve the overall accuracy of the model. The improvement of the uniformity of the control points will improve the accuracy of the model at a lower uniformity; the uniformity of the control points can improve the accuracy of the model at a lower uniformity. The uniformity of the control points can improve the accuracy of the model at a lower uniformity. The uniformity of the control points can improve the accuracy of the real 3D model at a lower uniformity. The uniformity of the control points can be used as an evaluation indicator in the deployment of field control points.
Unmanned aerial vehicle (UAV) tilt-photography technology has become the mainstream of the construction of three-dimensional real-field models with its advantages of low cost, high efficiency and high precision. The accuracy of the real 3D model is affected by many factors. This study is mainly focused on the point of view of the uniformity of the control point distribution, to explore its impact on the accuracy of the real 3D model, and propose a more general measure of control point uniformity. Two experiments with different numbers of control points are designed, and each experiment contains three different uniformity distribution schemes. Aerial images of the experimental area were obtained by UAV, and six schemes were adopted to participate in model. By analyzing the model accuracy, the results show that: the accuracy of the real 3D model is poorer when the uniformity of the control points is lower, and the elevation accuracy is worse than the plane accuracy. Increasing the uniformity of the control points will improve the overall accuracy of the model. The improvement of the uniformity of the control points will improve the accuracy of the model at a lower uniformity; the uniformity of the control points can improve the accuracy of the model at a lower uniformity. The uniformity of the control points can improve the accuracy of the model at a lower uniformity. The uniformity of the control points can improve the accuracy of the real 3D model at a lower uniformity. The uniformity of the control points can be used as an evaluation indicator in the deployment of field control points.
2021, 46(1): 28-35.
doi: 10.12265/j.gnss.2020100904
Abstract:
Real-time acquisition of geographic location information of smart mobile terminals is the key to the realization of an augmented reality (AR) real-scene smart navigation system. In order to improve the accuracy of GPS positioning for smart terminals, a GPS combined positioning optimization method based on Kalman filtering and improved DBSCAN clustering algorithm is proposed. Kalman filtering is performed on the position coordinate data collected by the GPS system to remove large data fluctuations and control the positioning error range. Using DBSCAN clustering algorithm for classification denoising and secondary clustering, the arithmetic mean value of the data in the class and the total number of data between the classes are weighted to find the center of gravity, and the position coordinates are determined. The experimental results show that the proposed algorithm can effectively improve the GPS single-point positioning accuracy, reduce positioning errors, and at the same time well meet the real-time and robustness requirements of the AR real-world intelligent navigation system.
Real-time acquisition of geographic location information of smart mobile terminals is the key to the realization of an augmented reality (AR) real-scene smart navigation system. In order to improve the accuracy of GPS positioning for smart terminals, a GPS combined positioning optimization method based on Kalman filtering and improved DBSCAN clustering algorithm is proposed. Kalman filtering is performed on the position coordinate data collected by the GPS system to remove large data fluctuations and control the positioning error range. Using DBSCAN clustering algorithm for classification denoising and secondary clustering, the arithmetic mean value of the data in the class and the total number of data between the classes are weighted to find the center of gravity, and the position coordinates are determined. The experimental results show that the proposed algorithm can effectively improve the GPS single-point positioning accuracy, reduce positioning errors, and at the same time well meet the real-time and robustness requirements of the AR real-world intelligent navigation system.
2021, 46(1): 36-42.
doi: 10.12265/j.gnss.2020082801
Abstract:
The inertial measurement unit (IMU) is disturbed by its own temperature, bias, vibration and other factors, so the pose is easy to diverge when integrating, and the monocular vision positioning accuracy is poor when the robot moves rapidly. Therefore, this paper studies a visual inertial synchronous simultaneous localization and mapping (SLAM) method based on tight coupling. Firstly, the location problem of visualodometry (VO) is studied. In order to reduce the mismatching of feature points, the feature points extraction method based on Oriented FAST and Rotated BRIEF (ORB) is adopted. Then the mathematical model of IMU is constructed, and the discrete integral of the motion model is obtained by using the median method. Finally, the pose of monocular vision is aligned with IMU trajectory, and the optimal state estimation of robot motion is obtained by nonlinear optimization based on sliding window. The two experiments were verified by constructing the simulation scene ard comparing with the monocular ORB-SLAM algorithm. The results show that the proposed method is better than visual odometer alone, and the positioning accuracy is controlled at about 0.4 m, which is 30% higher than the traditional tracking model.
The inertial measurement unit (IMU) is disturbed by its own temperature, bias, vibration and other factors, so the pose is easy to diverge when integrating, and the monocular vision positioning accuracy is poor when the robot moves rapidly. Therefore, this paper studies a visual inertial synchronous simultaneous localization and mapping (SLAM) method based on tight coupling. Firstly, the location problem of visualodometry (VO) is studied. In order to reduce the mismatching of feature points, the feature points extraction method based on Oriented FAST and Rotated BRIEF (ORB) is adopted. Then the mathematical model of IMU is constructed, and the discrete integral of the motion model is obtained by using the median method. Finally, the pose of monocular vision is aligned with IMU trajectory, and the optimal state estimation of robot motion is obtained by nonlinear optimization based on sliding window. The two experiments were verified by constructing the simulation scene ard comparing with the monocular ORB-SLAM algorithm. The results show that the proposed method is better than visual odometer alone, and the positioning accuracy is controlled at about 0.4 m, which is 30% higher than the traditional tracking model.
2021, 46(1): 43-49.
doi: 10.12265/j.gnss.2020101002
Abstract:
According to the coordinate time series results of 19 CMONOC reference stations in Gansu Province, the maximum likelihood estimate (MLE) was used to explore the optimal noise model of each reference station, the velocity field of the reference station was determined, and the crustal movement in Gansu Province was analyzed. The research results show that the noise characteristics of each coordinate component of the CMONOC reference station in Gansu Province are quite different. "WN+FN" is the optimal noise model, which can better describe the noise characteristics of the three components of the reference station coordinate time series, and The estimated rate uncertainty is 4 to 15 times when only white noise is considered. The average rate of horizontal movement of the CMONOC reference station in Gansu Province under the framework of ITRF14 is 34.54 mm/a and the direction of movement is SEE 98.07°; the average rate of horizontal movement relative to the Eurasian plate is 6.49 mm/a and the direction of movement is NEE 79.23°.
According to the coordinate time series results of 19 CMONOC reference stations in Gansu Province, the maximum likelihood estimate (MLE) was used to explore the optimal noise model of each reference station, the velocity field of the reference station was determined, and the crustal movement in Gansu Province was analyzed. The research results show that the noise characteristics of each coordinate component of the CMONOC reference station in Gansu Province are quite different. "WN+FN" is the optimal noise model, which can better describe the noise characteristics of the three components of the reference station coordinate time series, and The estimated rate uncertainty is 4 to 15 times when only white noise is considered. The average rate of horizontal movement of the CMONOC reference station in Gansu Province under the framework of ITRF14 is 34.54 mm/a and the direction of movement is SEE 98.07°; the average rate of horizontal movement relative to the Eurasian plate is 6.49 mm/a and the direction of movement is NEE 79.23°.
2021, 46(1): 50-56.
doi: 10.12265/j.gnss.2020100901
Abstract:
With the increasing complexity of modern electromagnetic environment, navigation receiver is at higher risk of various interference. Narrowband interference and pulse interference are common means of suppressing interference on satellite navigation signals. Different interference signals have different time-frequency domain characteristics, and their influence on satellite navigation signals is also very different, which is mainly reflected in the carrier-to-noise ratio and bit error rate. In view of the lack of research on pulse interference performance in China, a formula of anti-interference quality factor suitable for pulse interference is proposed by comparing narrowband interference performance evaluation method. This paper deduces the method of calculating the equivalent carrier-to-noise ratio in time domain under pulse interference, and verifies the result through simulation. The result shows that the calculation error of equivalent carrier-to-noise ratio under pulse interference with different duty ratio is less than 0.5 dB, and the result is quite accurate.
With the increasing complexity of modern electromagnetic environment, navigation receiver is at higher risk of various interference. Narrowband interference and pulse interference are common means of suppressing interference on satellite navigation signals. Different interference signals have different time-frequency domain characteristics, and their influence on satellite navigation signals is also very different, which is mainly reflected in the carrier-to-noise ratio and bit error rate. In view of the lack of research on pulse interference performance in China, a formula of anti-interference quality factor suitable for pulse interference is proposed by comparing narrowband interference performance evaluation method. This paper deduces the method of calculating the equivalent carrier-to-noise ratio in time domain under pulse interference, and verifies the result through simulation. The result shows that the calculation error of equivalent carrier-to-noise ratio under pulse interference with different duty ratio is less than 0.5 dB, and the result is quite accurate.
2021, 46(1): 57-61.
doi: 10.12265/j.gnss.2020102001
Abstract:
In order to compare and analyze BDS-3/Galileo compatible frequency pseudorange single-point positioning accuracy, based on the measured data of MGEX distributed tracking stations, singal point positioning accuracy of pseudorange combination of dual-system compatible frequencies and non-compatible frequenry of BDS-3 and Galileo are analyzed, together with that of single frequency of BDS-3 and Galileo respectively. It is found through research that BDS-3/Galileo combination effectively improves the visible number of satellites and the geometric structure of satellite spatial distribution compared to a single system. In terms of single system positioning, the single point positioning accuracy of B1C and B2a pseudorange of BDS-3 is better than that of comesponding compatible frequenry of Galileo. In terms of dual-system positioning, the single point positioning accuracy of compatible frequenry pseudorange combination of BDS-3/Galileo is better than that of non-compatible frequenry combination. and the dual-system combination positioning improves the Galileo single-system positioning accuracy better BDS-3, which indicates that the design of BDS-3 compatible frequency effectively improves the compatibility with Galileo system.
In order to compare and analyze BDS-3/Galileo compatible frequency pseudorange single-point positioning accuracy, based on the measured data of MGEX distributed tracking stations, singal point positioning accuracy of pseudorange combination of dual-system compatible frequencies and non-compatible frequenry of BDS-3 and Galileo are analyzed, together with that of single frequency of BDS-3 and Galileo respectively. It is found through research that BDS-3/Galileo combination effectively improves the visible number of satellites and the geometric structure of satellite spatial distribution compared to a single system. In terms of single system positioning, the single point positioning accuracy of B1C and B2a pseudorange of BDS-3 is better than that of comesponding compatible frequenry of Galileo. In terms of dual-system positioning, the single point positioning accuracy of compatible frequenry pseudorange combination of BDS-3/Galileo is better than that of non-compatible frequenry combination. and the dual-system combination positioning improves the Galileo single-system positioning accuracy better BDS-3, which indicates that the design of BDS-3 compatible frequency effectively improves the compatibility with Galileo system.
2021, 46(1): 62-67, 88.
doi: 10.12265/j.gnss.2020102002
Abstract:
For two coordinate reference frames which have no direct conversion parameters, a new method is developed to solve the complex and inefficient problem of traditional multi-step "transition" transformation. This paper takes the coordinates and velocities of 714 stations released by EUREF as an example to convert them from the ETRF2014 to the ETRF2000. The results show that, the coordinate and velocity difference between the traditional method and the method proposed in this paper is in the order of$ {10}^{-8} $ meters and $ {10}^{-9} $ meters per year, respectively. The analysis results verify the feasibility of the calculation method.
For two coordinate reference frames which have no direct conversion parameters, a new method is developed to solve the complex and inefficient problem of traditional multi-step "transition" transformation. This paper takes the coordinates and velocities of 714 stations released by EUREF as an example to convert them from the ETRF2014 to the ETRF2000. The results show that, the coordinate and velocity difference between the traditional method and the method proposed in this paper is in the order of
2021, 46(1): 68-76.
doi: 10.12265/j.gnss.2020102802
Abstract:
The construction of BDS-3 has been completed. At this time, it is very meaningful and necessary to carry out the study and analysis of BDS-3 data quality and positioning performance. Observation data of MGEX stations were used to assess the observation data quality and pseudorange single-point positioning accuracy of BDS-3. Meanwhile, the positioning accuracy of BDS-2 and GPS were compared with BDS-3. The results show that the data integrity rate of BDS-3 at each station is above 95%. The average signal-to-noise ratio of each frequency band is higher than 45 dB·Hz, but signal-to-noise ratio of GEO satellite fluctuates frequently. The average value multipath error of various types of BDS-3 satellites are all less than 35 cm, and the pseudorange noise of most BDS-3 satellites is generally less than 0.3 m. Compared with BDS-2 and BDS-3, the positioning accuracy of BDS-2/BDS-3 has been improved to different extents, but the improvement of BDS-3 positioning accuracy in high latitude areas is very small. BDS-3 can obtain a positioning accuracy better than 3 m and 4 m in horizontal and vertical directions in all regions of the world, which is roughly comparable to GPS positioning performance.
The construction of BDS-3 has been completed. At this time, it is very meaningful and necessary to carry out the study and analysis of BDS-3 data quality and positioning performance. Observation data of MGEX stations were used to assess the observation data quality and pseudorange single-point positioning accuracy of BDS-3. Meanwhile, the positioning accuracy of BDS-2 and GPS were compared with BDS-3. The results show that the data integrity rate of BDS-3 at each station is above 95%. The average signal-to-noise ratio of each frequency band is higher than 45 dB·Hz, but signal-to-noise ratio of GEO satellite fluctuates frequently. The average value multipath error of various types of BDS-3 satellites are all less than 35 cm, and the pseudorange noise of most BDS-3 satellites is generally less than 0.3 m. Compared with BDS-2 and BDS-3, the positioning accuracy of BDS-2/BDS-3 has been improved to different extents, but the improvement of BDS-3 positioning accuracy in high latitude areas is very small. BDS-3 can obtain a positioning accuracy better than 3 m and 4 m in horizontal and vertical directions in all regions of the world, which is roughly comparable to GPS positioning performance.
2021, 46(1): 77-82.
doi: 10.12265/j.gnss.2020111902
Abstract:
The unmanned helicopter equipped with LiDAR for transmission line inspection has the advantages of high accuracy and low cost. In order to obtain high-precision three-dimensional point cloud high-precision geospatial coordinates of high-precision transmission lines, it adopts three different positioning service methods, including base station differential post processed kinematic (PPK), Jiangsu Province CORS (JS-CORS), Qianxun location (QX-CORS), etc. to inspect transmission line inspections, and analyze of the point positioning accuracy and point cloud quality obtained under the three types of positioning. The actual results show that the average error between the plane check point and the elevation check point of the base station differential post-processing positioning method is within 0.1 m, which has the highest accuracy and the best data quality. The accuracy of the JS-CORS real-time positioning method and the Qianxun real-time positioning method are second. It provides a reference for unmanned helicopter carrying LiDAR for power transmission line inspection and selection of positioning methods.
The unmanned helicopter equipped with LiDAR for transmission line inspection has the advantages of high accuracy and low cost. In order to obtain high-precision three-dimensional point cloud high-precision geospatial coordinates of high-precision transmission lines, it adopts three different positioning service methods, including base station differential post processed kinematic (PPK), Jiangsu Province CORS (JS-CORS), Qianxun location (QX-CORS), etc. to inspect transmission line inspections, and analyze of the point positioning accuracy and point cloud quality obtained under the three types of positioning. The actual results show that the average error between the plane check point and the elevation check point of the base station differential post-processing positioning method is within 0.1 m, which has the highest accuracy and the best data quality. The accuracy of the JS-CORS real-time positioning method and the Qianxun real-time positioning method are second. It provides a reference for unmanned helicopter carrying LiDAR for power transmission line inspection and selection of positioning methods.
2021, 46(1): 83-88.
doi: 10.12265/j.gnss.2020120902
Abstract:
In view of the difference of period and noise characteristics in different regions, this paper takes the coordinate time series of 27 CORS in Shandong Province from 2015 to 2018 as the research object, and analyzed the period and noise of coordinate components of each station on the basis of data preprocessing. The results show that, there is no strict whole periodic signal in coordinate time series, and the periodic motion in U direction is relatively regular. The spectrum index of coordinate component shows that the noise model of most stations is white noise (WN) + flicker noise (FN). Using the maximum likelihood estimation criterion, the best noise model of coordinate time series in Shandong CORS station is WN + FN, and the best noise model in E and U direction is WN + FN. The best noise model is WN + FN + random walk noise (RWN).
In view of the difference of period and noise characteristics in different regions, this paper takes the coordinate time series of 27 CORS in Shandong Province from 2015 to 2018 as the research object, and analyzed the period and noise of coordinate components of each station on the basis of data preprocessing. The results show that, there is no strict whole periodic signal in coordinate time series, and the periodic motion in U direction is relatively regular. The spectrum index of coordinate component shows that the noise model of most stations is white noise (WN) + flicker noise (FN). Using the maximum likelihood estimation criterion, the best noise model of coordinate time series in Shandong CORS station is WN + FN, and the best noise model in E and U direction is WN + FN. The best noise model is WN + FN + random walk noise (RWN).
2021, 46(1): 89-97, 111.
doi: 10.12265/j.gnss.2020090802
Abstract:
The preliminary analysis of the atmospheric water vapor detection performance of Beidou-3 global satellite navigation system (BDS-3), which has just been deployed in China, can make better use of the meteorological detection potential of BDS-3. In this paper several methods are compared using data from diffent stations around the world. The results are representative and convincing. The results of the study showed, comparing BDS-3/PWV with GPS/PWV, the average deviation (BIAS) was preferable to 1.0 mm, the root mean square error (RMSE) was better than 2.0 mm, and the correlation coefficients were all above 94%; The mean of the absolute values of the difference between of BDS-3/PWV and GPS/PWV (MEAN) was 1.1 mm, which was 71% lower than BDS-2; The RMSE of BDS-3/PWV and GPS/PWV was 1.4 mm, which was 63% lower than BDS-2. Comparing BDS-3/PWV with ERA5/PWV, BIAS was preferable to 2.9 mm, RMSE was better than 2.8 mm, and the correlation coefficient was above 92%. The MEAN of BDS-3/PWV and ERA5/PWV was 2.1 mm, which was better than BDS-2 reduced by 48%; The RMSE of BDS-3/PWV and ERA5/PWV was 1.6 mm, which was 57% lower than BDS-2. The water vapor detection performance of BDS-3 was much better than BDS-2, which was in good agreement with GPS and ERA5 water vapor detection results.
The preliminary analysis of the atmospheric water vapor detection performance of Beidou-3 global satellite navigation system (BDS-3), which has just been deployed in China, can make better use of the meteorological detection potential of BDS-3. In this paper several methods are compared using data from diffent stations around the world. The results are representative and convincing. The results of the study showed, comparing BDS-3/PWV with GPS/PWV, the average deviation (BIAS) was preferable to 1.0 mm, the root mean square error (RMSE) was better than 2.0 mm, and the correlation coefficients were all above 94%; The mean of the absolute values of the difference between of BDS-3/PWV and GPS/PWV (MEAN) was 1.1 mm, which was 71% lower than BDS-2; The RMSE of BDS-3/PWV and GPS/PWV was 1.4 mm, which was 63% lower than BDS-2. Comparing BDS-3/PWV with ERA5/PWV, BIAS was preferable to 2.9 mm, RMSE was better than 2.8 mm, and the correlation coefficient was above 92%. The MEAN of BDS-3/PWV and ERA5/PWV was 2.1 mm, which was better than BDS-2 reduced by 48%; The RMSE of BDS-3/PWV and ERA5/PWV was 1.6 mm, which was 57% lower than BDS-2. The water vapor detection performance of BDS-3 was much better than BDS-2, which was in good agreement with GPS and ERA5 water vapor detection results.
2021, 46(1): 98-104.
doi: 10.12265/j.gnss.2020110401
Abstract:
Due to the problems of the diversity of the scale, the unclear boundary and the complex spectral information of the ground objects, the performance of the statistical method and machine learning method for the change detection of the high complexity street view images is poor. Therefore, a street view images change detection method combining semantic segmentation model and graph cuts (GC) is proposed in this paper. Firstly, the DeeplabV3+ semantic segmentation model combined with migration learning is used to pre-train the Camvid data set to obtain the pre-trained model in this method; Then a small number of annotated samples from the data set of this paper were used to Fine Tune the pre-training model, which was respectively used for semantic segmentation of street view images in two periods. Then GC method is used to remove the sky, roads,vegetation and other factors, which is impacting on the street view. Finally, change vector analysis (CVA) is used to obtain the difference images, and binarization and accuracy evaluation were carried out for the difference images. The results show that the overall accuracy of the proposed method is better than the Otsu method (OTSU), K-means method, Segnet network migration learning method and DeeplabV3+ network migration learning method, it is a feasible method for detecting changes in street view images.
Due to the problems of the diversity of the scale, the unclear boundary and the complex spectral information of the ground objects, the performance of the statistical method and machine learning method for the change detection of the high complexity street view images is poor. Therefore, a street view images change detection method combining semantic segmentation model and graph cuts (GC) is proposed in this paper. Firstly, the DeeplabV3+ semantic segmentation model combined with migration learning is used to pre-train the Camvid data set to obtain the pre-trained model in this method; Then a small number of annotated samples from the data set of this paper were used to Fine Tune the pre-training model, which was respectively used for semantic segmentation of street view images in two periods. Then GC method is used to remove the sky, roads,vegetation and other factors, which is impacting on the street view. Finally, change vector analysis (CVA) is used to obtain the difference images, and binarization and accuracy evaluation were carried out for the difference images. The results show that the overall accuracy of the proposed method is better than the Otsu method (OTSU), K-means method, Segnet network migration learning method and DeeplabV3+ network migration learning method, it is a feasible method for detecting changes in street view images.
2021, 46(1): 105-111.
doi: 10.12265/j.gnss.2020102005
Abstract:
In order to solve the problems of working condition monitoring of the ocean current machine and the difficulty of long-distance communication and data transmission between the ocean current machine and the shore, the BeiDou Navigation Satellite System (BDS) was chosen to be applied to the ocean current machine's positioning and communication in the sea. The characteristics of ocean currents and several common operating conditions of ocean current machines are analyzed. The positioning principle of ocean current machine based on BDS-RNSS and the short message communication characteristics of BDS are introduced. “Bit Splicing-LZW” double data compression is applied in the short message communication system. A main control system suitable for ocean current machine communication and draft a communication plan between ocean current machine and shore user terminal is designed, aiming to improve communication efficiency and increase data transmission volume.
In order to solve the problems of working condition monitoring of the ocean current machine and the difficulty of long-distance communication and data transmission between the ocean current machine and the shore, the BeiDou Navigation Satellite System (BDS) was chosen to be applied to the ocean current machine's positioning and communication in the sea. The characteristics of ocean currents and several common operating conditions of ocean current machines are analyzed. The positioning principle of ocean current machine based on BDS-RNSS and the short message communication characteristics of BDS are introduced. “Bit Splicing-LZW” double data compression is applied in the short message communication system. A main control system suitable for ocean current machine communication and draft a communication plan between ocean current machine and shore user terminal is designed, aiming to improve communication efficiency and increase data transmission volume.
2021, 46(1): 112-118.
doi: 10.12265/j.gnss.2020110601
Abstract:
Natural Gas Hydrate (NGH) development technology has become the frontier of scientific and technological innovation in the world. In the development of NGH resources, both safety development and environmental protection should be paid equal attention, in order to accelerate the commercialization of NGH production in the seabed, it is urgent to strengthen the long-term environment monitoring of seabed exploitation. This paper designs an environment monitoring and assessment system for NGH exploitation based on BeiDou Navigation Satellite System (BDS). By displaying the atmosphere, sea water, seabed and underground well of 'four in one' 3D visualization marine stereoscopic space scene, we can obtain the real-time data acquisition and remote transmission of NGH exploitation environment sensors, and realize the real-time safety analysis, tracking and warning function of exploitation environment in the seabed.
Natural Gas Hydrate (NGH) development technology has become the frontier of scientific and technological innovation in the world. In the development of NGH resources, both safety development and environmental protection should be paid equal attention, in order to accelerate the commercialization of NGH production in the seabed, it is urgent to strengthen the long-term environment monitoring of seabed exploitation. This paper designs an environment monitoring and assessment system for NGH exploitation based on BeiDou Navigation Satellite System (BDS). By displaying the atmosphere, sea water, seabed and underground well of 'four in one' 3D visualization marine stereoscopic space scene, we can obtain the real-time data acquisition and remote transmission of NGH exploitation environment sensors, and realize the real-time safety analysis, tracking and warning function of exploitation environment in the seabed.
2019, 44(2): 1-12.
doi: DOI:10.13442/j.gnss.1008-9268.2019.02.001
摘要：
自卫星导航系统诞生以来，人们发展了多种增强技术和手段，并建立了大批增强系统，以满足用户更高精度和完好性的需求.由于卫星导航增强技术客观上晚于基本系统出现，且都是按需独立建立，因此不可避免地存在着“碎片”和“补丁”式发展问题，相互之间功能重叠，缺乏统一的规划和标准，未成体系化建设.本文回顾和总结了卫星导航增强技术的产生和发展历程，梳理了相关技术内涵与定义，并重点介绍了中国北斗卫星导航系统（BDS）增强体系的建设和发展情况.在此基础上，结合5G通信、低轨卫星等新兴技术，对卫星导航增强体系未来发展动态进行了展望和分析，并对未来北斗定位、导航与授时（PNT）综合服务中的增强体系建设提出了建议.
自卫星导航系统诞生以来，人们发展了多种增强技术和手段，并建立了大批增强系统，以满足用户更高精度和完好性的需求.由于卫星导航增强技术客观上晚于基本系统出现，且都是按需独立建立，因此不可避免地存在着“碎片”和“补丁”式发展问题，相互之间功能重叠，缺乏统一的规划和标准，未成体系化建设.本文回顾和总结了卫星导航增强技术的产生和发展历程，梳理了相关技术内涵与定义，并重点介绍了中国北斗卫星导航系统（BDS）增强体系的建设和发展情况.在此基础上，结合5G通信、低轨卫星等新兴技术，对卫星导航增强体系未来发展动态进行了展望和分析，并对未来北斗定位、导航与授时（PNT）综合服务中的增强体系建设提出了建议.
2018, 43(1): 43-48.
doi: 0.13442/j.gnss.1008-9268.2018.01.008
摘要：
随着北斗卫星导航系统的建设与发展推动全球卫星导航事业在民航的发展。介绍了卫星导航系统的定位误差通过与作为真值数据的组合导航定位数据进行比较仿真分析了实测数据下精度因子与可见星数目的占比分布北斗卫星导航系统在低海拔平原地区和高海拔山脉地区均可以提供实时导航定位服务且定位结果均符合《北斗卫星导航系统公开服务性能规范》标准，满足用户的定位要求。
随着北斗卫星导航系统的建设与发展推动全球卫星导航事业在民航的发展。介绍了卫星导航系统的定位误差通过与作为真值数据的组合导航定位数据进行比较仿真分析了实测数据下精度因子与可见星数目的占比分布北斗卫星导航系统在低海拔平原地区和高海拔山脉地区均可以提供实时导航定位服务且定位结果均符合《北斗卫星导航系统公开服务性能规范》标准，满足用户的定位要求。
2017, 42(1): 70-73.
doi: 10.13442/j.gnss.1008-9268.2017.01.014
摘要：
NMEA0183 协议解析模块是导航系统中至关重要的软件模块,该模块的健壮性和高效性直接关系到整个导航系统的性能。为了能及时并高效解析NMEA数据流,分开处理NMEA数据流解析与数据显示,降低解析模块与显示模块的耦合性,提出一种基于正则表达式和MVC架构的NMEA0183协议解析方法。整个解析模块可分为四个阶段,原始NMEA数据流存储,NMEA数据流高效解析,NMEA数据校验,NMEA数据显示。目前该方法已应用到GPS 导航产品中,实测表明，该解析模块高效可靠,数据流解析显示实时性好。
NMEA0183 协议解析模块是导航系统中至关重要的软件模块,该模块的健壮性和高效性直接关系到整个导航系统的性能。为了能及时并高效解析NMEA数据流,分开处理NMEA数据流解析与数据显示,降低解析模块与显示模块的耦合性,提出一种基于正则表达式和MVC架构的NMEA0183协议解析方法。整个解析模块可分为四个阶段,原始NMEA数据流存储,NMEA数据流高效解析,NMEA数据校验,NMEA数据显示。目前该方法已应用到GPS 导航产品中,实测表明，该解析模块高效可靠,数据流解析显示实时性好。
2017, 42(2): 25-31.
doi: doi:10.13442/j.gnss.1008-9268.2017.02.006
摘要：
本文以高山峡谷地区以及城市建筑群区域GNSS卫星受山体及建筑物遮挡的实际问题为出发点,通过选取不同的卫星方位角模拟不同遮挡环境,研究GPS／BDS、GPS／GLONAS和GPS／BDS／GLONASS组合系统伪距单点定位模型对于单GPS、单BDS系统在不同遮挡环境下的定位精度和三维导航可用性等方面的改善情况。结果表明,组合系统相对于单系统,增加了可见卫星数,降低了PDOP值,当观测条件不佳时,可以很好地改善定位精度和提高三维导航可用性。
本文以高山峡谷地区以及城市建筑群区域GNSS卫星受山体及建筑物遮挡的实际问题为出发点,通过选取不同的卫星方位角模拟不同遮挡环境,研究GPS／BDS、GPS／GLONAS和GPS／BDS／GLONASS组合系统伪距单点定位模型对于单GPS、单BDS系统在不同遮挡环境下的定位精度和三维导航可用性等方面的改善情况。结果表明,组合系统相对于单系统,增加了可见卫星数,降低了PDOP值,当观测条件不佳时,可以很好地改善定位精度和提高三维导航可用性。
2018, 43(6): 1-7.
doi: doi:10.13442/j.gnss.1008-9268.2018.06.001
摘要：
卫星导航欺骗干扰信号检测是卫星导航接收机实施欺骗干扰抑制、防止产生错误定位和测速、定时信息的必要步骤.在介绍了导航战背景下卫星导航欺骗干扰技术的基础上,分析比较了当前主要卫星导航欺骗干扰信号检测技术的实现难度、效果和场景适应性,指出了现阶段卫星导航接收机端最具研究价值的欺骗干扰信号检测技术.最后对欺骗干扰检测技术研究的趋势和发展方向进行了总结展望.
卫星导航欺骗干扰信号检测是卫星导航接收机实施欺骗干扰抑制、防止产生错误定位和测速、定时信息的必要步骤.在介绍了导航战背景下卫星导航欺骗干扰技术的基础上,分析比较了当前主要卫星导航欺骗干扰信号检测技术的实现难度、效果和场景适应性,指出了现阶段卫星导航接收机端最具研究价值的欺骗干扰信号检测技术.最后对欺骗干扰检测技术研究的趋势和发展方向进行了总结展望.
2017, 42(6): 16-23.
doi: 10.13442/j.gnss.1008-9268.2017.06.003
摘要：
针对在不同截止卫星高度角的情况下,GPS、BDS、GPS／BDS、GPS／GALILEO、BDS／GALILEO 、GPS／BDS／GALILEO间伪距单点定位精度的差异,本文对多系统融合伪距单点定位的数学模型和误差项处理方法进行了研究,以香港CORS站HKMW站点全天的数据为实验数据,在截止卫星高度角10°、15°、20°、30°、40°的情况下,进行了GPS、BDS、GPS／BDS、GPS／GALILEO、BDS／GALILEO、GPS／BDS／GALILEO伪距单点定位解算。结果表明,GPS／BDS／GALILEO组合系统在X、Y、Z各方向的定位精度都优于单系统,定位结果更加稳定,尤其在截止高度角达到30°、40°时,单系统的定位精度急剧下降,历元可用率降低,而GPS／BDS／GALILEO组合系统仍能满足定位的要求。
针对在不同截止卫星高度角的情况下,GPS、BDS、GPS／BDS、GPS／GALILEO、BDS／GALILEO 、GPS／BDS／GALILEO间伪距单点定位精度的差异,本文对多系统融合伪距单点定位的数学模型和误差项处理方法进行了研究,以香港CORS站HKMW站点全天的数据为实验数据,在截止卫星高度角10°、15°、20°、30°、40°的情况下,进行了GPS、BDS、GPS／BDS、GPS／GALILEO、BDS／GALILEO、GPS／BDS／GALILEO伪距单点定位解算。结果表明,GPS／BDS／GALILEO组合系统在X、Y、Z各方向的定位精度都优于单系统,定位结果更加稳定,尤其在截止高度角达到30°、40°时,单系统的定位精度急剧下降,历元可用率降低,而GPS／BDS／GALILEO组合系统仍能满足定位的要求。
2017, 42(1): 95-99.
doi: 10.13442/j.gnss.1008-9268.2017.01.019
摘要：
本文基于RTKLIB现有的框架,对精密单点定位中的主要误差模型进行分析,通过调用其误差改正模型算法,实现了精密单点定位解算;对定位误差分析表明,X、Y、Z三个方向均在80个历元内误差达到0.1 m,而且逐步减小趋于稳定。定位误差在180个历元达到7 cm.
本文基于RTKLIB现有的框架,对精密单点定位中的主要误差模型进行分析,通过调用其误差改正模型算法,实现了精密单点定位解算;对定位误差分析表明,X、Y、Z三个方向均在80个历元内误差达到0.1 m,而且逐步减小趋于稳定。定位误差在180个历元达到7 cm.
2017, 42(3): 32-37.
doi: 10.13442/j.gnss.1008-9268.2017.03.007
摘要：
GNSS伪距单点定位速度快且不存在整周模糊度问题,其原理简单易于编程实现,所以在进行GNSS数据处理时,经常用到该方法。本文以GPS、GLONASS、BDS多模融合为例,简单介绍多模融合存在的坐标统一、时间基准统一问题,再详细介绍多模融合伪距单点定位原理以及解算模型,基于Visual Studio2010平台,编写GPS、GLONASS、BDS多模融合的伪距单点定位及单点测速程序。结合相关算例,对该程序多系统伪距单点定位的精度以及单点测速精度进行分析。
GNSS伪距单点定位速度快且不存在整周模糊度问题,其原理简单易于编程实现,所以在进行GNSS数据处理时,经常用到该方法。本文以GPS、GLONASS、BDS多模融合为例,简单介绍多模融合存在的坐标统一、时间基准统一问题,再详细介绍多模融合伪距单点定位原理以及解算模型,基于Visual Studio2010平台,编写GPS、GLONASS、BDS多模融合的伪距单点定位及单点测速程序。结合相关算例,对该程序多系统伪距单点定位的精度以及单点测速精度进行分析。
2018, 43(1): 19-24.
doi: doi:10.13442/j.gnss.1008-9268.2018.01.004
摘要：
伽利略系统(Galileo)是全球四大卫星导航系统之一,目前已初步具备全球定位能力。研究Galileo的信号质量和双／三频定位性能不仅对Galileo系统应用具有重要价值,对多全球卫星导航系统（GNSS）融合定位也有重要促进作用。在使用基准站网(MGEX)地面跟踪站的基础上,分析了伽利略信号的载噪比、多路径、以及双／三频精密单点定位(PPP)的定位精度。结果表明,Galileo与GPS相比,载噪比E5> E5a≈E5b≈L5>E1≈L1>L2,多路径误差E5
伽利略系统(Galileo)是全球四大卫星导航系统之一,目前已初步具备全球定位能力。研究Galileo的信号质量和双／三频定位性能不仅对Galileo系统应用具有重要价值,对多全球卫星导航系统（GNSS）融合定位也有重要促进作用。在使用基准站网(MGEX)地面跟踪站的基础上,分析了伽利略信号的载噪比、多路径、以及双／三频精密单点定位(PPP)的定位精度。结果表明,Galileo与GPS相比,载噪比E5> E5a≈E5b≈L5>E1≈L1>L2,多路径误差E5
2018, 43(5): 77-83.
doi: 10.13442/j.gnss.1008-9268.2018.05.015
摘要：
本文利用GAMIT10.61软件对重庆8个CORS站GPS数据和BDS数据进行处理,并从基线重复性、单日解时间序列、联合解平差等三个方面对GPS和BDS解算结果进行对比分析.结果表明，GPS解算结果整体优于BDS,且单BDS解与单GPS解在水平方向差值小于0.7 cm,高程方向差值在1～3 cm;基于GAMIT 10.61的BDS基线解算重复性在南北方向上1.39 mm+0.205 mm×10 -8 ,东西方向上为3.10 mm+0.252×10-8 ,高程方向上为7.81 mm+2.001×10-8,基线长度方向上2.13 mm+0.384×10-8,解算精度能满足高精度数据处理要求.
本文利用GAMIT10.61软件对重庆8个CORS站GPS数据和BDS数据进行处理,并从基线重复性、单日解时间序列、联合解平差等三个方面对GPS和BDS解算结果进行对比分析.结果表明，GPS解算结果整体优于BDS,且单BDS解与单GPS解在水平方向差值小于0.7 cm,高程方向差值在1～3 cm;基于GAMIT 10.61的BDS基线解算重复性在南北方向上1.39 mm+0.205 mm×10 -8 ,东西方向上为3.10 mm+0.252×10-8 ,高程方向上为7.81 mm+2.001×10-8,基线长度方向上2.13 mm+0.384×10-8,解算精度能满足高精度数据处理要求.
2019, 44(2): 1-12.
doi: DOI:10.13442/j.gnss.1008-9268.2019.02.001
Abstract:
2018, 43(6): 8-13.
doi: doi:10.13442/j.gnss.1008-9268.2018.06.002
Abstract:
2017, 42(5): 53-58.
doi: 10.13442/j.gnss.1008-9268.2017.05.011
Abstract:
2019, 44(1): 1-9.
doi: DOI:10.13442/j.gnss.1008-9268.2019.01.001
Abstract:
2019, 44(5): 1-9.
doi: DOI:10.13442/j.gnss.1008-9268.2019.05.001
Abstract:
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ISSN 1008-9268
CN 41-1317/TN
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