Pub Date : 2017-05-01DOI: 10.1109/CPGPS.2017.8075116
Bowen Li, Bo Zhang, Dongkai Yang, Yongqiang Qi
Global Navigation Satellite System-Reflection (GNSS-R) technology has attracted more and more attention in remote sensing and navigation field, especially in the ocean remote sensing. A feasible GNSS-R model based on reverse thinking method was proposed in our previous work. In this paper, in order to make the model applicable to the case of higher wind speed, we presented an improved GNSS-R model by expanding the range of time delay from 5 to 9 chips. A mathematical derivation was built to guide the design of the model. The number of reflected signals was 30 and the delay interval was 0.3 chip in the newly built model by optimizing the accuracy and computation of the model. Moreover, a GNSS-R software simulator was designed based on the improved GNSS-R model. The simulation reflected signals were compared with the experimental data collected in Yantai, Shandong province. Good agreement was found in the simulation results and experimental data, and the correlation coefficient between two correlation power curves was 0.9964, with the error in retrieving wind speed of 0.8 m/s. These results proved that the improved GNSS-R model and the simulator design can be applied in simulation of GNSS ocean reflected signals.
{"title":"An improved model and simulator design of GNSS ocean reflected signals","authors":"Bowen Li, Bo Zhang, Dongkai Yang, Yongqiang Qi","doi":"10.1109/CPGPS.2017.8075116","DOIUrl":"https://doi.org/10.1109/CPGPS.2017.8075116","url":null,"abstract":"Global Navigation Satellite System-Reflection (GNSS-R) technology has attracted more and more attention in remote sensing and navigation field, especially in the ocean remote sensing. A feasible GNSS-R model based on reverse thinking method was proposed in our previous work. In this paper, in order to make the model applicable to the case of higher wind speed, we presented an improved GNSS-R model by expanding the range of time delay from 5 to 9 chips. A mathematical derivation was built to guide the design of the model. The number of reflected signals was 30 and the delay interval was 0.3 chip in the newly built model by optimizing the accuracy and computation of the model. Moreover, a GNSS-R software simulator was designed based on the improved GNSS-R model. The simulation reflected signals were compared with the experimental data collected in Yantai, Shandong province. Good agreement was found in the simulation results and experimental data, and the correlation coefficient between two correlation power curves was 0.9964, with the error in retrieving wind speed of 0.8 m/s. These results proved that the improved GNSS-R model and the simulator design can be applied in simulation of GNSS ocean reflected signals.","PeriodicalId":340067,"journal":{"name":"2017 Forum on Cooperative Positioning and Service (CPGPS）","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116685793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-05-01DOI: 10.1109/CPGPS.2017.8075127
N. Zang, Bofeng Li, Yunzhong Shen
This contribution mainly addresses PPP augmentation with current Galileo constellation. The GPS-only, GPS+Galileo, and GPS+Galileo+BDS PPP will be numerically studied with both single- and dual-frequency signals. The results show that the single-frequency GPS PPP solutions in obstructed situation can reach only meter level accuracy while GPS+Galileo and GPS+Galileo+BDS PPP solutions get 0.15m and 0.5m accuracy in horizontal and vertical direction, respectively. In dual-frequency kinematic PPP experiments, the GPS-only cannot provide centimeter solutions in obstructed case whereas the Galileo augmented PPP significantly improves the positioning accuracy up to centimeter in all three components.
{"title":"PPP augmentation with current Galileo and BeiDou constellations","authors":"N. Zang, Bofeng Li, Yunzhong Shen","doi":"10.1109/CPGPS.2017.8075127","DOIUrl":"https://doi.org/10.1109/CPGPS.2017.8075127","url":null,"abstract":"This contribution mainly addresses PPP augmentation with current Galileo constellation. The GPS-only, GPS+Galileo, and GPS+Galileo+BDS PPP will be numerically studied with both single- and dual-frequency signals. The results show that the single-frequency GPS PPP solutions in obstructed situation can reach only meter level accuracy while GPS+Galileo and GPS+Galileo+BDS PPP solutions get 0.15m and 0.5m accuracy in horizontal and vertical direction, respectively. In dual-frequency kinematic PPP experiments, the GPS-only cannot provide centimeter solutions in obstructed case whereas the Galileo augmented PPP significantly improves the positioning accuracy up to centimeter in all three components.","PeriodicalId":340067,"journal":{"name":"2017 Forum on Cooperative Positioning and Service (CPGPS）","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114974917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-05-01DOI: 10.1109/CPGPS.2017.8075092
Pengfei Wu, Dezhi Duan, Guochen Wang, Runfeng Zhang, Jiachong Chang
In this paper, the model of thermally induced nonreciprocal error is established in three-dimensional cylindrical coordinate system. Make finite-element thermal analysis for fiber loop to get the simulated result of temperature field inside the fiber loop by ANSYS based on the actual temperature on the surface of fiber loop detected under the static condition, get heat transfer rates by comparing area of regions where temperature changes inside the fiber loop section at the equal time intervals, through which we can guess the relationship between the thermally induced nonreciprocal error and heat-transfer rate. Different heat transfer rates are achieved by changing layers of fiber loop under the premise of the same fiber length and the same thermal load, then gain temperature curves of center node on different models. Program the algorithm based on the Shupe effect and the theory of thermal stress to calculate the thermally induced nonreciprocity error for different fiber loop models, which is convenient to determine the optimal layers based on quadrupole winding method. This paper shows the relationship between thermally induced nonreciprocal error and the heat transfer rate.
{"title":"The influence of heat transfer rate on the thermally induced nonreciprocal error of FOG","authors":"Pengfei Wu, Dezhi Duan, Guochen Wang, Runfeng Zhang, Jiachong Chang","doi":"10.1109/CPGPS.2017.8075092","DOIUrl":"https://doi.org/10.1109/CPGPS.2017.8075092","url":null,"abstract":"In this paper, the model of thermally induced nonreciprocal error is established in three-dimensional cylindrical coordinate system. Make finite-element thermal analysis for fiber loop to get the simulated result of temperature field inside the fiber loop by ANSYS based on the actual temperature on the surface of fiber loop detected under the static condition, get heat transfer rates by comparing area of regions where temperature changes inside the fiber loop section at the equal time intervals, through which we can guess the relationship between the thermally induced nonreciprocal error and heat-transfer rate. Different heat transfer rates are achieved by changing layers of fiber loop under the premise of the same fiber length and the same thermal load, then gain temperature curves of center node on different models. Program the algorithm based on the Shupe effect and the theory of thermal stress to calculate the thermally induced nonreciprocity error for different fiber loop models, which is convenient to determine the optimal layers based on quadrupole winding method. This paper shows the relationship between thermally induced nonreciprocal error and the heat transfer rate.","PeriodicalId":340067,"journal":{"name":"2017 Forum on Cooperative Positioning and Service (CPGPS）","volume":"98 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120978611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-05-01DOI: 10.1109/CPGPS.2017.8075150
Fucheng Song, Peng Gao, Shuangshuang Shi
Constellation of regional BDS has been completed with five Geostationary Earth Orbit (GEO) satellites, five Inclined Geosynchronous Satellite Orbit (IGSO) satellites and four Medium Earth Orbit (MEO) satellites, which can provide positioning, navigation, timing, short-message communication and other services for regional users. China's BDS continues to develop a global system in near future. In order to analyze and assess the positioning performance of BDS B1 frequency, we discuss and analyze the performance of regional BDS (5 GEO + 5 IGSO + 4 MEO) and global BDS (5 GEO + 3 IGSO + 27 MEO) with simulated data in term of satellite visibility, PDOP value and positioning accuracy in the most regions of China. Wuhan station is also selected to test positioning performance for a single day. The results show that the global BDS can provide Chinese users with better service. Compared with the regional BDS, the global BDS improves significantly. The number of average visible satellites increases by 8–10, the average PDOP value decreases by 1–3, and the average positioning accuracy increases by 2–3 m.
{"title":"Positioning performance analysis and assessment for BDS B1 frequency based on simulation","authors":"Fucheng Song, Peng Gao, Shuangshuang Shi","doi":"10.1109/CPGPS.2017.8075150","DOIUrl":"https://doi.org/10.1109/CPGPS.2017.8075150","url":null,"abstract":"Constellation of regional BDS has been completed with five Geostationary Earth Orbit (GEO) satellites, five Inclined Geosynchronous Satellite Orbit (IGSO) satellites and four Medium Earth Orbit (MEO) satellites, which can provide positioning, navigation, timing, short-message communication and other services for regional users. China's BDS continues to develop a global system in near future. In order to analyze and assess the positioning performance of BDS B1 frequency, we discuss and analyze the performance of regional BDS (5 GEO + 5 IGSO + 4 MEO) and global BDS (5 GEO + 3 IGSO + 27 MEO) with simulated data in term of satellite visibility, PDOP value and positioning accuracy in the most regions of China. Wuhan station is also selected to test positioning performance for a single day. The results show that the global BDS can provide Chinese users with better service. Compared with the regional BDS, the global BDS improves significantly. The number of average visible satellites increases by 8–10, the average PDOP value decreases by 1–3, and the average positioning accuracy increases by 2–3 m.","PeriodicalId":340067,"journal":{"name":"2017 Forum on Cooperative Positioning and Service (CPGPS）","volume":"91 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126879372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-05-01DOI: 10.1109/CPGPS.2017.8075137
Chen Zhengsheng, Z. Qinghua, Sun Dashuang, Lv Hao, Zhang Runtao, Liu Xuerui, Chen Jinlong
In the research and precise applications of Global Navigation Satellite System(GNSS), it is often necessary to choose a reference satellite for differential combination calculation, such as Real Time Kinematic(RTK) positioning, Uncalibrated Phase Delays(UPD) solving based on between satellite difference etc. In a specific period, the more reasonable selection of the reference satellite is, the better achievements of the calculation results will be. In this paper, three reference satellites selection principles are used: 1) the observation period is long enough; 2) satellite elevation angle is high enough and 3) reference satellite is not changed in a specified period. Based on these principles, two common reference satellite selection algorithms are compared, including the algorithm of Maximal Elevation Angle in Whole Period and the algorithm of Longest Period Span with a restriction condition of maximal elevation angle during the specified period. After analyzing the changes of elevation angle of all the visible GNSS satellites of three observation stations in different latitude with time, it is found that there is a parabola relationship between elevation angles (over 30°) of satellite and epochs. This paper presents a fast reference satellite selection algorithm based on the maximum elevation angle at the epoch period center. The analysis results show that the new algorithm is more easily realized under the same conditions than the other two algorithms, and the selected reference satellite not only has enough available period, but also has better geometry structure.
{"title":"A reference satellite selection method based on maximal elevation angle during the observation period","authors":"Chen Zhengsheng, Z. Qinghua, Sun Dashuang, Lv Hao, Zhang Runtao, Liu Xuerui, Chen Jinlong","doi":"10.1109/CPGPS.2017.8075137","DOIUrl":"https://doi.org/10.1109/CPGPS.2017.8075137","url":null,"abstract":"In the research and precise applications of Global Navigation Satellite System(GNSS), it is often necessary to choose a reference satellite for differential combination calculation, such as Real Time Kinematic(RTK) positioning, Uncalibrated Phase Delays(UPD) solving based on between satellite difference etc. In a specific period, the more reasonable selection of the reference satellite is, the better achievements of the calculation results will be. In this paper, three reference satellites selection principles are used: 1) the observation period is long enough; 2) satellite elevation angle is high enough and 3) reference satellite is not changed in a specified period. Based on these principles, two common reference satellite selection algorithms are compared, including the algorithm of Maximal Elevation Angle in Whole Period and the algorithm of Longest Period Span with a restriction condition of maximal elevation angle during the specified period. After analyzing the changes of elevation angle of all the visible GNSS satellites of three observation stations in different latitude with time, it is found that there is a parabola relationship between elevation angles (over 30°) of satellite and epochs. This paper presents a fast reference satellite selection algorithm based on the maximum elevation angle at the epoch period center. The analysis results show that the new algorithm is more easily realized under the same conditions than the other two algorithms, and the selected reference satellite not only has enough available period, but also has better geometry structure.","PeriodicalId":340067,"journal":{"name":"2017 Forum on Cooperative Positioning and Service (CPGPS）","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130499265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-05-01DOI: 10.1109/CPGPS.2017.8075126
Zongpeng Pan, Hongzhou Chai, Yang Chong, Yulong Kong, Rui Wang, Xiaodong Pan
The current constellation of GLONASS uses frequency division multiple access (FDMA), meaning the code observations of different satellites have inter-frequency biases (IFB). The code IFB is usually included in the pseudo-range residuals when performing precise point positioning (PPP). However, it will affect the convergence of PPP when the value of code IFB is large. In this contribution, a GLONASS PPP algorithm considering the influence of pseudo-range IFB is presented. The unified model of the algorithm in the ionosphere-free combination PPP and original observation PPP is given. At the same time, the validity of this algorithm is verified through the GLONASS observation data. The results show that the algorithm can effectively weaken the influence of the code IFB and the convergence speed and residual distribution of the GLONASS PPP considering the influence of code IFB is better than traditional method.
{"title":"GLONASS precise point positioning considering the influence of code inter-frequency biases","authors":"Zongpeng Pan, Hongzhou Chai, Yang Chong, Yulong Kong, Rui Wang, Xiaodong Pan","doi":"10.1109/CPGPS.2017.8075126","DOIUrl":"https://doi.org/10.1109/CPGPS.2017.8075126","url":null,"abstract":"The current constellation of GLONASS uses frequency division multiple access (FDMA), meaning the code observations of different satellites have inter-frequency biases (IFB). The code IFB is usually included in the pseudo-range residuals when performing precise point positioning (PPP). However, it will affect the convergence of PPP when the value of code IFB is large. In this contribution, a GLONASS PPP algorithm considering the influence of pseudo-range IFB is presented. The unified model of the algorithm in the ionosphere-free combination PPP and original observation PPP is given. At the same time, the validity of this algorithm is verified through the GLONASS observation data. The results show that the algorithm can effectively weaken the influence of the code IFB and the convergence speed and residual distribution of the GLONASS PPP considering the influence of code IFB is better than traditional method.","PeriodicalId":340067,"journal":{"name":"2017 Forum on Cooperative Positioning and Service (CPGPS）","volume":"329 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122738906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-05-01DOI: 10.1109/CPGPS.2017.8075110
Sen Huang, Shuxin Chen, Kun Chen, Zhuowei Liu, Jianhua Chen, Hao Wu
The traditional GNSS spoofing signals power distribution strategy only considers availability and validity in single channel mode without multiple channel mode. Therefore, a new strategy based on acquisition and tracing performance threshold is proposed. The relationship between the signal acquisition/tracking performance and carrier-to-noise ratio (C/N0) is analyzed. Then the influence of spoofing signal power on C/N0 is also analyzed through taking cross-correlation interference into consideration. The optimal spoofing power is calculated by the strategy under the C/N0 constraints and corresponding objective functions to different spoofing signal detecting. Simulations show that spoofing signal injection will be realized if the multiple spoofing power is −143.8dBW and denial power is 158.86dBW or the minimum elevation spoofing power is −124.04dBW. The concealment of interference is enhanced when it deals with the wideband white noise detection.
{"title":"A power distributing strategy of GNSS spoofing signal under dual-threshold","authors":"Sen Huang, Shuxin Chen, Kun Chen, Zhuowei Liu, Jianhua Chen, Hao Wu","doi":"10.1109/CPGPS.2017.8075110","DOIUrl":"https://doi.org/10.1109/CPGPS.2017.8075110","url":null,"abstract":"The traditional GNSS spoofing signals power distribution strategy only considers availability and validity in single channel mode without multiple channel mode. Therefore, a new strategy based on acquisition and tracing performance threshold is proposed. The relationship between the signal acquisition/tracking performance and carrier-to-noise ratio (C/N0) is analyzed. Then the influence of spoofing signal power on C/N0 is also analyzed through taking cross-correlation interference into consideration. The optimal spoofing power is calculated by the strategy under the C/N0 constraints and corresponding objective functions to different spoofing signal detecting. Simulations show that spoofing signal injection will be realized if the multiple spoofing power is −143.8dBW and denial power is 158.86dBW or the minimum elevation spoofing power is −124.04dBW. The concealment of interference is enhanced when it deals with the wideband white noise detection.","PeriodicalId":340067,"journal":{"name":"2017 Forum on Cooperative Positioning and Service (CPGPS）","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122378652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-05-01DOI: 10.1109/CPGPS.2017.8075154
Yijian Cui, Xiaolin Meng, Qusen Chen, Yang Gao, Changxue Xu, Simon Roberts, Yi-Ting Wang
For Connected and Autonomous Vehicle (CAV) applications, the location solution is desired to provide better than 0.1m real-time positioning accuracy. This level of accuracy can only be achieved by using geodetic GNSS receivers under an open sky observation condition, and each unit costs around £20,000. This kind of geodetic GNSS receiver is not a good option for mass market use in terms of price and ubiquity aspects. Therefore, using low-cost receiver to achieve real-time, high accuracy and ubiquitous positioning performance could be a future trend. This paper will first establish a framework of assessing low-cost receivers based on required navigation performance (RNP) concept in aviation and required accuracy categories in ITS. Then adynamic test that was conducted to simulate the future CAV driving environment will be introduced. Under the guidance of the former established framework, the collected data was post-processed to explore the real positioning performance of both two grades receivers. By comparing real-time/post-processed results and high-end/low-cost receivers, the limitations and technical gaps between two types of receivers, as well as current positioning solution and required positioning performance will be identified.
{"title":"Feasibility analysis of low-cost GNSS receivers for achieving required positioning performance in CAV applications","authors":"Yijian Cui, Xiaolin Meng, Qusen Chen, Yang Gao, Changxue Xu, Simon Roberts, Yi-Ting Wang","doi":"10.1109/CPGPS.2017.8075154","DOIUrl":"https://doi.org/10.1109/CPGPS.2017.8075154","url":null,"abstract":"For Connected and Autonomous Vehicle (CAV) applications, the location solution is desired to provide better than 0.1m real-time positioning accuracy. This level of accuracy can only be achieved by using geodetic GNSS receivers under an open sky observation condition, and each unit costs around £20,000. This kind of geodetic GNSS receiver is not a good option for mass market use in terms of price and ubiquity aspects. Therefore, using low-cost receiver to achieve real-time, high accuracy and ubiquitous positioning performance could be a future trend. This paper will first establish a framework of assessing low-cost receivers based on required navigation performance (RNP) concept in aviation and required accuracy categories in ITS. Then adynamic test that was conducted to simulate the future CAV driving environment will be introduced. Under the guidance of the former established framework, the collected data was post-processed to explore the real positioning performance of both two grades receivers. By comparing real-time/post-processed results and high-end/low-cost receivers, the limitations and technical gaps between two types of receivers, as well as current positioning solution and required positioning performance will be identified.","PeriodicalId":340067,"journal":{"name":"2017 Forum on Cooperative Positioning and Service (CPGPS）","volume":"133 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122902529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-05-01DOI: 10.1109/CPGPS.2017.8075125
S. Xin, Xiaotao Li, J. Geng, E. Jiang, Qiang Wen
With the development of precise point positioning (PPP) techniques, the real-time PPP service is also progressing. The realization of this real-time system can develop the market of PPP and it can also do some real-time researches, such as earthquake, etc. In addition, multi-GNSS can increase the number of satellites and also good constellation geometries. Therefore, it is beneficial to the positioning performance in terms of availability and reliability. This paper mainly introduces the structure of multi-GNSS real-time precise point positioning service system and the measures about how to build the platform. And it also discusses the differences between real-time PPP and post-processing PPP, and the differences between single-system and dual-system PPP. Certainly, it also briefly introduces the theories and methods of real-time satellite clock error and PPP computations. The experiments are carried out and the positioning achievement is analyzed. Based on the experimental results, the positioning precision and the convergence efficiency of dual-system are better than the GPS-only system. All 3D components of positions can reach centimeter-level accuracy.
{"title":"The implementation of multi-GNSS real-time precise point positioning service system: GPS/GLONASS","authors":"S. Xin, Xiaotao Li, J. Geng, E. Jiang, Qiang Wen","doi":"10.1109/CPGPS.2017.8075125","DOIUrl":"https://doi.org/10.1109/CPGPS.2017.8075125","url":null,"abstract":"With the development of precise point positioning (PPP) techniques, the real-time PPP service is also progressing. The realization of this real-time system can develop the market of PPP and it can also do some real-time researches, such as earthquake, etc. In addition, multi-GNSS can increase the number of satellites and also good constellation geometries. Therefore, it is beneficial to the positioning performance in terms of availability and reliability. This paper mainly introduces the structure of multi-GNSS real-time precise point positioning service system and the measures about how to build the platform. And it also discusses the differences between real-time PPP and post-processing PPP, and the differences between single-system and dual-system PPP. Certainly, it also briefly introduces the theories and methods of real-time satellite clock error and PPP computations. The experiments are carried out and the positioning achievement is analyzed. Based on the experimental results, the positioning precision and the convergence efficiency of dual-system are better than the GPS-only system. All 3D components of positions can reach centimeter-level accuracy.","PeriodicalId":340067,"journal":{"name":"2017 Forum on Cooperative Positioning and Service (CPGPS）","volume":"93 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127907544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-05-01DOI: 10.1109/CPGPS.2017.8075102
Xiaohua Xu, Daocheng Yu, Jia Luo
Seasonal variations of gravity waves over the globe in the stratosphere are investigated using radio occultation data from the Constellation Observing System for Meteorology, Ionosphere and Climate mission from September 2006 to June 2016. The global distributions of 10-year averaged seasonal means of gravity waves indicate that potential energy is large over tropical and subtropical latitudes (30°S-30°N) in all seasons, as well as over middle and high latitudes in winter hemisphere. Gravity wave potential energy and the outgoing longwave radiation (OLR) which is a proxy for deep convection are negative correlated at equatorial latitudes. This suggests that convection is the primary source of gravity waves in the Tropics. At 50°N and 50°S, gravity waves are mainly generated by the diverse terrains of mountains, and either propagate upward or are filtered out under the effect of background zonal wind. Intense eastward wind, which mainly happens in winter hemisphere, makes great contributions to the upward propagation of gravity waves, while 0 m/s wind level, which is apparent in summer hemisphere, filters out most of the gravity waves. This can explain the seasonal variations of gravity waves at middle and high latitudes.
{"title":"Seasonal variations of global stratospheric gravity wave activity revealed by COSMIC RO data","authors":"Xiaohua Xu, Daocheng Yu, Jia Luo","doi":"10.1109/CPGPS.2017.8075102","DOIUrl":"https://doi.org/10.1109/CPGPS.2017.8075102","url":null,"abstract":"Seasonal variations of gravity waves over the globe in the stratosphere are investigated using radio occultation data from the Constellation Observing System for Meteorology, Ionosphere and Climate mission from September 2006 to June 2016. The global distributions of 10-year averaged seasonal means of gravity waves indicate that potential energy is large over tropical and subtropical latitudes (30°S-30°N) in all seasons, as well as over middle and high latitudes in winter hemisphere. Gravity wave potential energy and the outgoing longwave radiation (OLR) which is a proxy for deep convection are negative correlated at equatorial latitudes. This suggests that convection is the primary source of gravity waves in the Tropics. At 50°N and 50°S, gravity waves are mainly generated by the diverse terrains of mountains, and either propagate upward or are filtered out under the effect of background zonal wind. Intense eastward wind, which mainly happens in winter hemisphere, makes great contributions to the upward propagation of gravity waves, while 0 m/s wind level, which is apparent in summer hemisphere, filters out most of the gravity waves. This can explain the seasonal variations of gravity waves at middle and high latitudes.","PeriodicalId":340067,"journal":{"name":"2017 Forum on Cooperative Positioning and Service (CPGPS）","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127178797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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