The combination of Precision Point Positioning(PPP)with Multi-Global Navigation Satellite System(MultiGNSS),called MGPPP,can improve the positioning precision and shorten the convergence time more effectively than the...The combination of Precision Point Positioning(PPP)with Multi-Global Navigation Satellite System(MultiGNSS),called MGPPP,can improve the positioning precision and shorten the convergence time more effectively than the combination of PPP with only the BeiDou Navigation Satellite System(BDS).However,the Inter-System Bias(ISB)measurement of Multi-GNSS,including the time system offset,the coordinate system difference,and the inter-system hardware delay bias,must be considered for Multi-GNSS data fusion processing.The detected ISB can be well modeled and predicted by using a quadratic model(QM),an autoregressive integrated moving average model(ARIMA),as well as the sliding window strategy(SW).In this study,the experimental results indicate that there is no apparent difference in the ISB between BDS-2 and BDS-3 observations if B1I/B3I signals are used.However,an obvious difference in ISB can be found between BDS-2 and BDS-3 observations if B1I/B3I and B1C/B2a signals are used.Meanwhile,the precision of the Predicted ISB(PISB)on the next day of all stations is about 0.1−0.6 ns.Besides,to effectively utilize the PISB,a new strategy for predicting the PISB for MGPPP is proposed.In the proposed strategy,the PISB is used by adding two virtual observation equations,and an adaptive factor is adopted to balance the contribution of the Observed ISB(OISB)and the PISB to the final estimations of ISB.To validate the effectiveness of the proposed method,some experimental schemes are designed and tested under different satellite availability conditions.The results indicate that in open sky environment,the selective utilization of the PISB achieves almost the same positioning precision of MGPPP as the direct utilization of the PISB,but the convergence time of MGPPP is reduced by 7.1%at most in the north(N),east(E),and up(U)components.In the blocked sky environment,the selective utilization of the PISB contributes to more significant improvement of the positioning precision and convergence time than that in the open sky environment.Compared with the direct utilization of the PISB,the selective utilization of the PISB improves the positioning precision and convergence time by 6.7%and 12.7%at most in the N,E,and U components,respectively.展开更多
With the gradual development and modernization of satellite navigation systems,using observation information from multi-GNss has become one of the hot-spot issues in recent years.Multi-system loose combinations form d...With the gradual development and modernization of satellite navigation systems,using observation information from multi-GNss has become one of the hot-spot issues in recent years.Multi-system loose combinations form double-difference observation equations within their respective systems,and the positioning effect is improved.However,the interchangeability and compatible interoperability between global navigation satellite systems(GNSS)cannot be truly realized.At the same time,when the number of visible satellites decreases abruptly,the positioning performance deteriorates sharply.This paper focuses on the GNsS multi-system tight combination relative positioning technique,gives a mathe-matical model of multi-system tight combination relative positioning considering differential inter-system bias(DISB),and analyzes the time-varying characteristics of DISB at overlapping and non-overlapping frequencies among GPS/Galileo,GPS/BDS,and GPS/QZSS in terms of receiver brand,tem-perature,and receiver restart.The GNsS tight combination relative positioning performance is verified by static data from Curtin University and dynamic data measured at Taiyuan University of Technology.The results show that compared with loose combination,the ambiguity-fixed rate increases from 62.18%to 97.60%for static data and from 74.97%to 99.53%for dynamic data when the elevation mask angle is 50°,resulting in a significant improvement in positioning performance.展开更多
通过北斗三号精密单点定位服务信号(Precise Point Positioning B2b,PPP-B2b)差分码偏差(Differential Code Biases,DCB)对实时非组合精密单点定位(Uncombined Precise Point Positioning,UPPP)解算参数的影响进行研究。基于PPP-B2b服务...通过北斗三号精密单点定位服务信号(Precise Point Positioning B2b,PPP-B2b)差分码偏差(Differential Code Biases,DCB)对实时非组合精密单点定位(Uncombined Precise Point Positioning,UPPP)解算参数的影响进行研究。基于PPP-B2b服务的UPPP模型,分析了DCB对UPPP定位、收敛时间、对流层、钟差及斜向电离层解算的影响。在非组合模型下,采用北斗三号PPP-B2b实时精密单点定位(Real-Time Precise Point Positioning B2b,RTPPP-B2b)软件对接收机实测数据进行实验分析。实验结果表明:载波与伪距观测值权比为103∶1时,DCB对定位精度和收敛时间影响均较小,载波与伪距观测值权比为102∶1时,无DCB校正的UPPP定位误差收敛时间会变长;DCB对解算对流层天顶总延迟的影响可以忽略,对接收机钟差影响在亚纳秒级别;在使用UPPP提取斜向电离层过程中,DCB主要影响斜向电离层的计算精度。展开更多
A new on-line methodology is used to characterize the negative bias temperature instability （NBTI） without inherent recovery. Saturation drain voltage shift and mobility shift are extracted by ID-VD characterization...A new on-line methodology is used to characterize the negative bias temperature instability （NBTI） without inherent recovery. Saturation drain voltage shift and mobility shift are extracted by ID-VD characterizations, which were measured before stress, and after every certain stress phase, using the proportional differential operator （PDO） method. The new on-line methodology avoids the mobility linearity assumption as compared with the previous onthe-fly method. It is found that both reaction-diffusion and charge-injection processes are important in NBTI effect under either DC or AC stress. A similar activation energy, 0.15 eV, occurred in both DC and AC NBTI processes. Also degradation rate factor is independent of temperature below 90℃ and sharply increases above it. The frequency dependence of NBTI degradation shows that NBTI degradation is independent of frequencies. The carrier tunnelling and reaction-diffusion mechanisms exist simultaneously in NBTI degradation of sub-micron pMOSFETs, and the carrier tunnelling dominates the earlier NBTI stage and the reaction-diffusion mechanism follows when the generation rate of traps caused by carrier tunnelling reaches its maximum.展开更多
When only data transmission signals with a bandwidth of 1 MHz exist in the rover, the position can be obtained using the differential group delay data of the same-beam very long baseline interferometry (VLBI). The rel...When only data transmission signals with a bandwidth of 1 MHz exist in the rover, the position can be obtained using the differential group delay data of the same-beam very long baseline interferometry (VLBI). The relative position between a lunar rover and a lander can be determined with an error of several hundreds of meters. When the guidance information of the rover is used to determine relative position, the rover's wheel skid behavior and integral movement may influence the accuracy of the determined position. This paper proposes a new method for accurately determining relative position. The differential group delay and biased differential phase delay are obtained from the same-beam VLBI observation, while the modified biased differential phase delay is obtained using the statistic mean value of the differential group delay and the biased phase delay as basis. The small bias in the modified biased phase delay is estimated together with other parameters when the relative position of the rover is calculated. The effectiveness of the proposed method is confirmed using the same-beam VLBI observation data of SELENE. The radio sources onboard the rover and the lander are designed for same-beam VLBI observations. The results of the simulations of the differential delay of the same-beam VLBI observation between the rover and the lander show that the differential delay is sensitive to relative position. An approach to solving the relative position and a strategy for tracking are also introduced. When the lunar topography data near the rover are used and the observations are scheduled properly, the determined relative position of the rover may be nearly as accurate as that solved using differential phase delay data.展开更多
A common practice adopted for the pseudorange bias estimation and calibration assumes that Global Navigation Satellite System satellite-dependent pseudorange biases vary gently over time.Whereupon satellite pseudorang...A common practice adopted for the pseudorange bias estimation and calibration assumes that Global Navigation Satellite System satellite-dependent pseudorange biases vary gently over time.Whereupon satellite pseudorange biases are routinely estimated and provided as the products with low temporal resolution,e.g.,hourly or daily,by the agencies.The story sounds unquestionably perfect under the acquainted assumption.To validate the inadequacy of the above hypothesis we herein present an approach to the estimate the BeiDou Navigation Satellite System(BDS)pseudorange biases with high temporal resolution.Its feasibility,affecting factors,and necessity are discussed.Concretely,the Geometry-Free function models are first constructed to retrieve the linear combination of the pseudorange biases;then the pseudorange Observable-specific Signal Bias(OSB)values with respect to baseline frequencies(e.g.,BDS C2I/C6I)are estimated along with the ionosphere modeling;subsequently,all multi-frequency pseudorange OSBs are determined by using the ionospheric information with constraint conditions;finally,the possible Differential Code Bias sets are attainable with the estimated pseudorange OSBs.Using the observation data of four months when the estimated BDS pseudorange biases are stable,their reliability is demonstrated with the stability at the level of sub-nanosecond and the BeiDou-3 Navigation Satellite System(BDS-3)values more stable than that of BeiDou-2 Navigation Satellite System(BDS-2).The comparison between the estimated pseudorange biases and the Chinese Academy of Sciences products reveals that the accuracy of the estimated pseudorange biases is 0.2–0.4 ns.Moreover,the large magnitude of the short-term pseudorange bias variation in the tens of nanoseconds for the BDS-2 and BDS-3 are found in years 2021 and 2022,which are affected by two types of the satellite flex power for the BDS-2 and BDS-3,respectively.We stress that it’s necessary to estimate the BDS pseudorange biases with high temporal resolution in the case of the satellite flex power and the products currently provided by the agencies cannot reflect the true quantity under the circumstance.展开更多
基金supported by“The National Key Research and Development Program of China(No.2020YFA0713502)”“The National Natural Science Foundation of China(No.41874039)”+1 种基金“Jiangsu National Science Foundation(No.BK20191342)”“Fundamental Research Funds for the Central Universities(No.2019ZDPY-RH03)”。
文摘The combination of Precision Point Positioning(PPP)with Multi-Global Navigation Satellite System(MultiGNSS),called MGPPP,can improve the positioning precision and shorten the convergence time more effectively than the combination of PPP with only the BeiDou Navigation Satellite System(BDS).However,the Inter-System Bias(ISB)measurement of Multi-GNSS,including the time system offset,the coordinate system difference,and the inter-system hardware delay bias,must be considered for Multi-GNSS data fusion processing.The detected ISB can be well modeled and predicted by using a quadratic model(QM),an autoregressive integrated moving average model(ARIMA),as well as the sliding window strategy(SW).In this study,the experimental results indicate that there is no apparent difference in the ISB between BDS-2 and BDS-3 observations if B1I/B3I signals are used.However,an obvious difference in ISB can be found between BDS-2 and BDS-3 observations if B1I/B3I and B1C/B2a signals are used.Meanwhile,the precision of the Predicted ISB(PISB)on the next day of all stations is about 0.1−0.6 ns.Besides,to effectively utilize the PISB,a new strategy for predicting the PISB for MGPPP is proposed.In the proposed strategy,the PISB is used by adding two virtual observation equations,and an adaptive factor is adopted to balance the contribution of the Observed ISB(OISB)and the PISB to the final estimations of ISB.To validate the effectiveness of the proposed method,some experimental schemes are designed and tested under different satellite availability conditions.The results indicate that in open sky environment,the selective utilization of the PISB achieves almost the same positioning precision of MGPPP as the direct utilization of the PISB,but the convergence time of MGPPP is reduced by 7.1%at most in the north(N),east(E),and up(U)components.In the blocked sky environment,the selective utilization of the PISB contributes to more significant improvement of the positioning precision and convergence time than that in the open sky environment.Compared with the direct utilization of the PISB,the selective utilization of the PISB improves the positioning precision and convergence time by 6.7%and 12.7%at most in the N,E,and U components,respectively.
基金supported by the Natural Science Foundation of Shanxi Provincial(Grant No.202203021211153)the Basic Research Program of Shanxi Province(Grant No.202203021212284)+2 种基金Open Foundation of the State Key Laboratory of Satellite Navigation System and Equipment Technology(Grant No.CEPNT2022B07)the Open Foundation of the State Key Laboratory of Geodesy and Earth's Dynamics(Grant No.SKLGED2022-3-4)the research on application technology of Beidou in the field of energy and power(Grant No.CEEC2022-ZDYF-01).
文摘With the gradual development and modernization of satellite navigation systems,using observation information from multi-GNss has become one of the hot-spot issues in recent years.Multi-system loose combinations form double-difference observation equations within their respective systems,and the positioning effect is improved.However,the interchangeability and compatible interoperability between global navigation satellite systems(GNSS)cannot be truly realized.At the same time,when the number of visible satellites decreases abruptly,the positioning performance deteriorates sharply.This paper focuses on the GNsS multi-system tight combination relative positioning technique,gives a mathe-matical model of multi-system tight combination relative positioning considering differential inter-system bias(DISB),and analyzes the time-varying characteristics of DISB at overlapping and non-overlapping frequencies among GPS/Galileo,GPS/BDS,and GPS/QZSS in terms of receiver brand,tem-perature,and receiver restart.The GNsS tight combination relative positioning performance is verified by static data from Curtin University and dynamic data measured at Taiyuan University of Technology.The results show that compared with loose combination,the ambiguity-fixed rate increases from 62.18%to 97.60%for static data and from 74.97%to 99.53%for dynamic data when the elevation mask angle is 50°,resulting in a significant improvement in positioning performance.
文摘通过北斗三号精密单点定位服务信号(Precise Point Positioning B2b,PPP-B2b)差分码偏差(Differential Code Biases,DCB)对实时非组合精密单点定位(Uncombined Precise Point Positioning,UPPP)解算参数的影响进行研究。基于PPP-B2b服务的UPPP模型,分析了DCB对UPPP定位、收敛时间、对流层、钟差及斜向电离层解算的影响。在非组合模型下,采用北斗三号PPP-B2b实时精密单点定位(Real-Time Precise Point Positioning B2b,RTPPP-B2b)软件对接收机实测数据进行实验分析。实验结果表明:载波与伪距观测值权比为103∶1时,DCB对定位精度和收敛时间影响均较小,载波与伪距观测值权比为102∶1时,无DCB校正的UPPP定位误差收敛时间会变长;DCB对解算对流层天顶总延迟的影响可以忽略,对接收机钟差影响在亚纳秒级别;在使用UPPP提取斜向电离层过程中,DCB主要影响斜向电离层的计算精度。
文摘A new on-line methodology is used to characterize the negative bias temperature instability （NBTI） without inherent recovery. Saturation drain voltage shift and mobility shift are extracted by ID-VD characterizations, which were measured before stress, and after every certain stress phase, using the proportional differential operator （PDO） method. The new on-line methodology avoids the mobility linearity assumption as compared with the previous onthe-fly method. It is found that both reaction-diffusion and charge-injection processes are important in NBTI effect under either DC or AC stress. A similar activation energy, 0.15 eV, occurred in both DC and AC NBTI processes. Also degradation rate factor is independent of temperature below 90℃ and sharply increases above it. The frequency dependence of NBTI degradation shows that NBTI degradation is independent of frequencies. The carrier tunnelling and reaction-diffusion mechanisms exist simultaneously in NBTI degradation of sub-micron pMOSFETs, and the carrier tunnelling dominates the earlier NBTI stage and the reaction-diffusion mechanism follows when the generation rate of traps caused by carrier tunnelling reaches its maximum.
基金supported by the Hundred Talent Project(s) of Chinese Academy of Sciencesthe National Natural Science Foundation of China (Grant Nos.11073048 and 11073047)+1 种基金the Pujiang Project of Shanghai (Grant No.10PJ1411700)Shanghai Key Laboratory of Space Navigation and Position Techniques (Grant No.Y054262001)
文摘When only data transmission signals with a bandwidth of 1 MHz exist in the rover, the position can be obtained using the differential group delay data of the same-beam very long baseline interferometry (VLBI). The relative position between a lunar rover and a lander can be determined with an error of several hundreds of meters. When the guidance information of the rover is used to determine relative position, the rover's wheel skid behavior and integral movement may influence the accuracy of the determined position. This paper proposes a new method for accurately determining relative position. The differential group delay and biased differential phase delay are obtained from the same-beam VLBI observation, while the modified biased differential phase delay is obtained using the statistic mean value of the differential group delay and the biased phase delay as basis. The small bias in the modified biased phase delay is estimated together with other parameters when the relative position of the rover is calculated. The effectiveness of the proposed method is confirmed using the same-beam VLBI observation data of SELENE. The radio sources onboard the rover and the lander are designed for same-beam VLBI observations. The results of the simulations of the differential delay of the same-beam VLBI observation between the rover and the lander show that the differential delay is sensitive to relative position. An approach to solving the relative position and a strategy for tracking are also introduced. When the lunar topography data near the rover are used and the observations are scheduled properly, the determined relative position of the rover may be nearly as accurate as that solved using differential phase delay data.
文摘A common practice adopted for the pseudorange bias estimation and calibration assumes that Global Navigation Satellite System satellite-dependent pseudorange biases vary gently over time.Whereupon satellite pseudorange biases are routinely estimated and provided as the products with low temporal resolution,e.g.,hourly or daily,by the agencies.The story sounds unquestionably perfect under the acquainted assumption.To validate the inadequacy of the above hypothesis we herein present an approach to the estimate the BeiDou Navigation Satellite System(BDS)pseudorange biases with high temporal resolution.Its feasibility,affecting factors,and necessity are discussed.Concretely,the Geometry-Free function models are first constructed to retrieve the linear combination of the pseudorange biases;then the pseudorange Observable-specific Signal Bias(OSB)values with respect to baseline frequencies(e.g.,BDS C2I/C6I)are estimated along with the ionosphere modeling;subsequently,all multi-frequency pseudorange OSBs are determined by using the ionospheric information with constraint conditions;finally,the possible Differential Code Bias sets are attainable with the estimated pseudorange OSBs.Using the observation data of four months when the estimated BDS pseudorange biases are stable,their reliability is demonstrated with the stability at the level of sub-nanosecond and the BeiDou-3 Navigation Satellite System(BDS-3)values more stable than that of BeiDou-2 Navigation Satellite System(BDS-2).The comparison between the estimated pseudorange biases and the Chinese Academy of Sciences products reveals that the accuracy of the estimated pseudorange biases is 0.2–0.4 ns.Moreover,the large magnitude of the short-term pseudorange bias variation in the tens of nanoseconds for the BDS-2 and BDS-3 are found in years 2021 and 2022,which are affected by two types of the satellite flex power for the BDS-2 and BDS-3,respectively.We stress that it’s necessary to estimate the BDS pseudorange biases with high temporal resolution in the case of the satellite flex power and the products currently provided by the agencies cannot reflect the true quantity under the circumstance.
