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In order to study the temporal and spatial variation characteristics of the regional ionosphere, a regional ionosphere model was established based on the spherical harmonic function model and the GPS dual-frequency observation data of the European continuously operating reference station network.The reliability and stability of the differential CODE bias of the GPS satellites are analyzed, and the precision analysis and vertical total electron content of the ionosphere in the European region are carried out. The results showed that the average value of the DCB and CODE deviations of GPS satellites in the selected time period is less than 0.15 ns, and the root mean square is less than 0.2 ns.The root mean square of the difference between the calculated result and the vertical total electron content of CODE is less than 1.53 TECU.Applying the ionosphere in the European region to precise point positioning, the 327 d residual values are less than 0.3 cm in the E direction, less than 0.42 cm in the N direction, and less than 0.6 cm in the U direction, indicating that the addition of the ionosphere has the most obvious improvement in the U direction. In the 3D direction, the European region ionosphere is better than the CODE ionosphere, and the residual value is improved by 0.32 cm. [ABSTRACT FROM AUTHOR]

According to the problem of complex data processing caused by the correlation between stations and satellites in the double-difference network RTK(real-time kinematic), an algorithm of BDS un-difference network RTK with triple-frequency is proposed. Firstly, the integer linear relationship among extra-widelane, wide-lane and triple-frequency integer ambiguity is used to determine double-difference integer ambiguity between BDS network RTK reference stations. Then, according to the composition relationship between double-difference and un-difference integer ambiguity, un-difference integer ambiguity between reference stations is quickly determined at single epoch. On this basis, a high-precision region error correction model of BDS un-difference is established to realize the error correction and integer ambiguity fixing of use. This algorithm is tested by the measured triple-frequency data of BDS CORS(continuously operating reference stations) network. The results indicate that the algorithm of un-difference network RTK with triple-frequency can effectively overcome the correlation between station and satellite which is brought by the double-difference network RTK and make the operating type of the network RTK more flexible. [ABSTRACT FROM AUTHOR]

In order to avoid the problem of sorting in color image filtering, this paper proposed a multivariate filter method for color image based on the study of vector similarity. Firstly, in RGB color space, it defined the similarity measure between the color vectors by the distance and the angle to describe the color vector similarity consistent with the human visual perception. Secondly, it designed and constructed the color multivariate filter using the color similarity criterion, and analyzed and studied in depth the influence of the related parameters on the filtering performance. Finally, in order to verify the effectiveness of the proposed method, it was applied to the actual remote sensing image filtering. It can be seen from the experiment that the proposed method not only effectively solves the problem of sorting of the traditional filtering methods, but also overcomes the problems of blurring and unclear edges due to the filtering. In addition, compared with the results of other traditional methods, the results show that the proposed method not only can effectively filter many kinds of noise, but also maintains the original image information better, making the image information clear and fidelity. The visual effect of this filtering method is superior to the traditional, its objective evaluation index also has greatly improved . [ABSTRACT FROM AUTHOR]

In UWB indoor navigation, the accuracy of navigation resolution is greatly affected by non line of sight(NLOS) ranging error, and low filtering precision is influenced by uncertain system noise. To solve these problems, an improved robust Kalman filtering based on innovation is proposed and applied in ultra wideband(UWB) indoor navigation. On the foundation of the linear UWB indoor navigation model, the new method uses single innovation values to construct the matrix with robust factors and eliminate the influence of NLOS ranging error. Meanwhile, the new method does real-time estimation and corrects the system noise covariance matrix. Experimental result verifies the effectiveness of the new method. It is shown that the new method can not only effectively eliminate the influence of NLOS ranging error on navigation resolution, but also can further improve the filter precision and reliability in indoor navigation. [ABSTRACT FROM AUTHOR]

To extend the mathematical morphology for grayscale image to its alterative for color image, this paper proposed a color mathematical morphology based on fuzzy similarity defined on RGB color vector space. Firstly, in RGB color space, it defined the fuzzy similarity measure, which was consistent with the human visual perception, by using the distance and angle between two vectors to describe the similarity degree between the two colors. It defined the upper and lower bound functions in a collection of colors from in RGB color space by their similarity measures, and formulated the basic operations of the color mathematical morphology by using the upper and lower bounds for any pixel and its neighbor pixels within the structural unit centered the pixel, including dilation, erosion, opening and closing operations. This paper applied the proposed color morphological operations to the high resolution remote sensing images, and verified the deformation and smoothing ability to objects by comparing experiment, and explained its practicability and validity. [ABSTRACT FROM AUTHOR]

In order to efficiently obtain high quality information of highway alignment parameters, vehicle position orientation system is adopted to obtain information of dispersed coordinate and attitude, and line type parameters are calculated through post processing. This paper firstly presents a method of initial recognition based on curvature characteristic which is calculated by azimuth filtered by fast median filtering algorithm. Secondly, calculations and accurate recognition of line and circle type parameters are performed. Finally the parameters of approach curve are calculated by adjusted line and circle curve parameters. The method in this paper has been testified at a highway, and the results show that this method is practical. [ABSTRACT FROM AUTHOR]

Aiming at the situation of errors in observation data and coefficient matric in GPS Height anomaly, a robust total least squares (RTLS) is proposed with a IGGIII weight function based on standardized residuals. The method only takes the parts containing deviation in coefficient matrix into consideration. Taking the 80 groups GPS observation of benchmark as an example, the feasibility and accuracy of TRLS is analyzed compared with two kinds of experiment including 43 groups of data for fitting (4 groups of data with gross error) and 37 groups of data for testing. If the data have no robust, the result of RTLS is equal with robust LS. If the data have robust, the result of RTLS is better than robust LS. The experiment shows that the method of RTLS is the best choice when fitting GPS height anomaly. [ABSTRACT FROM AUTHOR]

The uncertainty of distance‐related error of global navigation satellite system is gradually increasing with the increase of distance between the reference stations and the rover station. Therefore, the dual ‐sys‐ tems of global positioning system (GPS) and BeiDou satellite navigation system (BDS) network real ‐ time kinematic (RTK) method was presented to meet the demand of high‐precision long range positioning RTK. Firstly, the wide‐lane ambiguities were fixed by the multi‐frequency observation data of GPS and BDS be‐ tween long‐range reference stations. The satellite clock errors can be eliminated by the double‐difference so‐ lution model, simultaneously the atmospheric error and satellite orbit errors can be weakened. Then the double ‐ difference carrier phase integer ambiguities can be fixed by the resolution model including atmo‐ spheric error and carrier phase ambiguity. The method of classification error corrections between long‐range reference stations network was used. The observation errors were classified, according to the characteris‐ tics of observation errors between long‐range reference station network. The ionosphere errors and non‐dis‐ persive errors of the rover station were calculated by using the reference stations’error correction and regional error interpolation. The atmospheric errors and satellite orbit errors of the rover station can be weakened by the method of interpolation. Then the errors of GPS/BDS carrier phase observation of the rover station were removed by the calculation errors. The carrier phase integer ambiguities of the rover station can be fixed by the method of resolution integer ambiguity with multi ‐frequency carrier phase, and the position of the rover station was obtained by the fixed ambiguities. The algorithm validation was carried out by the data on long ‐ range reference station network. Three long ‐ range reference stations and one rover station were used to test in Central China. The positioning accuracy of centimeter can be obtained by the algorithm of du‐ al ‐ systems of GPS and BDS network RTK. At the same time, single system can also get the centimeter level of position and the GPS is better than BDS. The method of dual ‐systems of GPS and BDS network RTK can guarantee the positioning accuracy of the rover station. The results of experiment indicate that the GPS/BDS long ‐ range network RTK can be realized and the centimeter level positioning accuracy can be achieved by this algorithm. [ABSTRACT FROM AUTHOR]

Objective: The uncertainty of influencing factors of BDS positioning is great in the disaster environment and emergency scene. The applicability and maneuverability of receiver in disaster emergency environment may not meet the needs of positioning. Therefore, the method of augmented positioning between long range stations on smart device was researched to meet the demand high-precision positioning in disaster emergency environment. The augmented positioning algorithm is convenient for high efficiency and easy to realize, and the user can use a very flexible data processing method. Methods: The un-difference error corrections between long-range reference stations was used of augmented positioning. The satellite clock error was eliminated and the atmospheric error and satellite orbit error can be weakened by the un-difference error corrections. The augmented positioning of user including pseudo-range, carrier phase and carrier phase smoothing pseudo-range between long range stations were achieved. And the demand of high-precision positioning of long range was meted by corrections of classified errors. The method of carrier phase smoothing pseudo-range by un-difference error corrections was used. The integer ambiguity was estimated by observations with eliminating errors and the pseudo-range was recalculated by the simple smoothing formula. The user station errors were removed or corrected by the reference station smoothing error corrections.The pseudo-range observations do not involve ambiguity with simple positioning mode and high- real-time performance, at the same time the accuracy of pseudo-range positioning can be improved by carrier phase observations. And this method can be better applied to the demand for high-precision positioning in disaster environment. The augmented positioning for specific receiver equipment was also integrated in the smart device. Results: Three reference stations between long range together with smart device and receiver in North China were used to test the augmented positioning. The positioning accuracy of dm or cm can be obtained by augmented positioning with pseudo-range and carrier phase smoothing of receiver, the accuracy on cm level obtained with carrier phase. The smart device can get the position on dm level of horizontal with carrier phase smoothing augmented positioning, and the augmented positioning with carrier phase was able to achieve the accuracy on cm level by fixed ambiguity or float ambiguity. The kinematic augmented positioning of smart device can get the positioning accuracy better than 1 meter with the test at Liaoning. Conclusions: The smart device can be used as the source of observation and the carrier of data processing for user receiver positioning. The Results: indicate that the method can achieve high-precision positioning with real-time dynamic centimetre, decimetre and sub-meter levels better than 1 meter. [ABSTRACT FROM AUTHOR]

Multi-spectral satellite image plays an increasingly important role in remote sensing applications. Its rich spectral characteristics and spectral correlation between bands provide richer feature information. Mathematical morphology helps to analyze the spatial correlation of pixel spectra due to its rigorous mathematical foundation, in order to enhance its ability to analyze spectral correlation between pixel bands. The paper is based on the principle of multivariate order of principal component analysis, and defines multi-spectral morphology. Firstly, the first principal component analysis is used to sort the pixel spectral vectors in the structural unit, and the upper and lower bound operators of the structural unit are defined accordingly. Then, using the upper and the lower bound to construct basic multi-spectral morphological operations, including dilation, erosion, opening and closing. Finally, the proposed multi-spectral morphological basic operations are applied to multi-spectral image processing. The performance of QuickBird, Ikonos and aerial remote sensing images is analyzed and studied. The experimental comparison is carried out to verify the target of the object spectral measurement smoothing ability and effective edge extraction, and also shows the practicability and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Objectives: BeiDou-3 satellite navigation system (BDS-3) has been officially completed and provides services, network real time kinematic(RTK) is the main means to improve positioning accuracy, we present a long-distance undifference network RTK method based on BDS multi frequency and multi system observation data. Methods: First, the ambiguity resolution model considering atmospheric error parameters is used to determine the integer ambiguity of multi-frequency carrier phase of long-distance BeiDou satellite navigation system (BDS) reference station.Then,the double difference integer ambiguity between reference stations is converted into non‐difference integer ambiguity of each reference station through linear change,and calculate the undifference observation error of each reference station. Considering the weakening of spatial correlation of observation errors between long-distance stations.According to the difference of error characteristics,obtain the correction number of classified undifference error of reference station network.Finally, by inverse distance weighted interpolation method, we calculate the error correction of mobile station, high precision positioning for users. Results: Select the measured data of long-distance continuous operation reference station network for experiment, the results show that: Compared with BeiDou-2 satellite navigation system (BDS-2), BDS-3 increases by 15.7%, 28% and 11.9% in E, N and U directions respectively. Compared with GPS, the positioning performance is equivalent or even better. The ambiguity fixing success rate and convergence time of multi-frequency data are better than GPS dual-frequency data. Dual system positioning results are better than single system, both of which can achieve centimeter level positioning of mobile stations. Conclusions: This method can avoid the correlation effect of double difference observations, high efficiency of spatial error calculation, mobile station positioning is more flexible, shows the advantages of BDS multi frequency observation data. [ABSTRACT FROM AUTHOR]

This paper presents a supervised image classification method based on fuzzy membership function to solve incorrect classification of high resolution remote sensing image, which caused by highlight detail information, the uncertainly of the pixels classification derived from the increase of the differences between pixels in the homogenous region, the uncertainly of classification decision and so on. First, Gaussian model is used to characterize the uncertainly of the membership of pixels; then the model is extended to build the image fuzzy membership function to define the uncertainly of the homogenous regions. To segment the image, the objective function is built by linear function of neural network, which the fuzzy membership functions and the membership degrees of the original fuzzy membership functions as input values. The proposed method is compared with the classification methods tested on the WorldView-2 panchromatic synthetic and real images. Through the qualitative and quantitative experiments, it can be found that the proposed method has better classification accuracy. [ABSTRACT FROM AUTHOR]

Uncalibrated phase delay at the receiver end may depend on the frequency of the signal received, which leads to mixed double difference ambiguity between GPS and BDS and, lost integer character. In order to solve this problem, inter-system biases between GPS and BDS need to be estimated or corrected. Taking the biases of time system, coordinate system and frequency between GPS and BDS into consideration, a computing model of GPS-BDS inter-system bias is deduced, based on which, different experiments verify the stability of inter-system biases. Experimental results show that GPS-BDS inter-system biases of different brand receivers have stability under certain conditions. GPS-BDS inter-system biases are nott influenced by antenna type and antenna cable length significantly. GPS-BDS tight combining with inter-system biases corrected performs well under poor observing condition, and improves the mean time-to-ambiguity-fixing by 33%, and the success rate of ambiguity-fixing by 31%. [ABSTRACT FROM AUTHOR]

Because the underwater gravity matching navigation is an important means to improve the underwater navigation accuracy of submarine, the research progress of marine gravity field, gravimeter and gravity gradiometer were reviewed. Firstly, the research progress of marine gravity field at home and abroad was summarized. The development history of SS series and KMS-DNSC-DTU series global gravity field models was reviewed. Secondly, the types, accuracy level and research progress of gravimeter/ gravity gradiometer at home and abroad were mainly introduced. The representative models of different types of gravimeters/ gravity gradients were listed. Finally, the phased research results of the research team of navigation and detection based on the information of aerospace-aeronauticsmarine integration in the Qian Xuesen Laboratory of Technology were briefly described. [ABSTRACT FROM AUTHOR]

Ambiguity fixing is the key to GNSS high-precision dynamic positioning. In order to analyze the performance of a GPS/BDS combined system on ambiguity search efficiency and the success rate of ambiguity fixing on a short baseline, this paper proposes an ambiguity search region correlation method based on the square roots of the eigenvalues of the variance/covariance matrix of ambiguity. This method compares and analyzes the ambiguity search region in a single system GPS,a single system BDS and combined GPS/BDS system, respectively. Experimental results show that the GPS and BDS combination influences the variance/covariance matrix of each single system, and reduces the search region of each single system. Furthermore, the statistical results show that the combined GPS/BDS system can improve the success rate of ambiguity fixing and the ambiguity search efficiency significantly within single- and dual- frequency observations. [ABSTRACT FROM AUTHOR]