Pub Date : 2017-05-01DOI: 10.1109/CPGPS.2017.8075107
Hao Mei, X. Zhan, Xin Zhang
Satellite-based communications, navigation, surveillance and air traffic management systems (CNS/ATM) are extremely promising in future use because of its great advantages in coverage and accuracy, yet can be seriously disabled by Global Navigation Satellite System (GNSS) vulnerability factors such as satellite anomaly, ionospheric perturbation, and electromagnetic interference. To improve the reliability of CNS/ATM system, this paper focuses on the influence of GNSS vulnerability on satellite-based navigation. Vulnerability of an airline is assessed based on the combination of vulnerability of each airspace, utilizing Advanced RAIM (ARAIM) user algorithm. Vulnerability assessment results of single airline are presented.
{"title":"GNSS vulnerability assessment method based on ARAIM user algorithm","authors":"Hao Mei, X. Zhan, Xin Zhang","doi":"10.1109/CPGPS.2017.8075107","DOIUrl":"https://doi.org/10.1109/CPGPS.2017.8075107","url":null,"abstract":"Satellite-based communications, navigation, surveillance and air traffic management systems (CNS/ATM) are extremely promising in future use because of its great advantages in coverage and accuracy, yet can be seriously disabled by Global Navigation Satellite System (GNSS) vulnerability factors such as satellite anomaly, ionospheric perturbation, and electromagnetic interference. To improve the reliability of CNS/ATM system, this paper focuses on the influence of GNSS vulnerability on satellite-based navigation. Vulnerability of an airline is assessed based on the combination of vulnerability of each airspace, utilizing Advanced RAIM (ARAIM) user algorithm. Vulnerability assessment results of single airline are presented.","PeriodicalId":340067,"journal":{"name":"2017 Forum on Cooperative Positioning and Service (CPGPS）","volume":"29 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":"125004050","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.2017.8075108
Li Zhang, Junping Li, T. Cui, Shuo Liu
Receiver Autonomous Integrity Monitoring (RAIM) has been successfully used for fault detection and exclusion in aviation applications. For airborne environment, the Geometric Dilution Of Precision (GDOP) and pseudo-range measurement quality is good. However, for urban canyon environment the GDOP may increase much and the pseudo-range measurement may contain huge multipath error. In this case, the exclusion of any pseudo-range measurement with multipath may make the GDOP increase much more and make the user position accuracy even worse. In this work, we propose an Urban Adapted-RAIM (UA-RAIM) algorithm to adjust the particular poor satellite geometry and multipath environment of urban canyon. Exclusion Accuracy Filter (EAF) is designed to check the position accuracy before and after fault exclusion. The fault satellite which can improve the positioning accuracy is processed using weighted estimation technique. Static experiment was carried out and a reflector was set to simulate the urban canyon environment. The user position errors in North, East and Up direction are 63.70%, 55.25% and 64.52% lower compared with the RAIM algorithm. From the urban vehicle tests, the vehicle positions of UA-RAIM are more like a straight line compared with RAIM. The 95% accuracy decreases from 20.32m to 16.55m using UA-RAIM and about 81.45% compared with the original.
{"title":"An adapted RAIM algorithm for urban canyon environment","authors":"Li Zhang, Junping Li, T. Cui, Shuo Liu","doi":"10.1109/CPGPS.2017.8075108","DOIUrl":"https://doi.org/10.1109/CPGPS.2017.8075108","url":null,"abstract":"Receiver Autonomous Integrity Monitoring (RAIM) has been successfully used for fault detection and exclusion in aviation applications. For airborne environment, the Geometric Dilution Of Precision (GDOP) and pseudo-range measurement quality is good. However, for urban canyon environment the GDOP may increase much and the pseudo-range measurement may contain huge multipath error. In this case, the exclusion of any pseudo-range measurement with multipath may make the GDOP increase much more and make the user position accuracy even worse. In this work, we propose an Urban Adapted-RAIM (UA-RAIM) algorithm to adjust the particular poor satellite geometry and multipath environment of urban canyon. Exclusion Accuracy Filter (EAF) is designed to check the position accuracy before and after fault exclusion. The fault satellite which can improve the positioning accuracy is processed using weighted estimation technique. Static experiment was carried out and a reflector was set to simulate the urban canyon environment. The user position errors in North, East and Up direction are 63.70%, 55.25% and 64.52% lower compared with the RAIM algorithm. From the urban vehicle tests, the vehicle positions of UA-RAIM are more like a straight line compared with RAIM. The 95% accuracy decreases from 20.32m to 16.55m using UA-RAIM and about 81.45% compared with the original.","PeriodicalId":340067,"journal":{"name":"2017 Forum on Cooperative Positioning and Service (CPGPS）","volume":"17 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":"129302751","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.2017.8075138
Rui Sun, D. Xue, Yucheng Zhang
Rear-End Collision has been considered as one of the most frequent accidents on roadways. In recent years, Global Satellite Navigation System (GNSS) with the merit of flexible and low cost, has exhibited the great potential for the rear-end Collision Avoidance Systems (CAS) for vehicles. Nevertheless, two main issues associated with the current rear-end CAS are: 1) accessing to high accuracy vehicle relative positioning and dynamic parameters; and 2) the reliable method to extract the car-following status from such information. This paper has developed a novel GNSS/compass fusion with the Adaptive Neuro Fuzzy Inference System (ANFIS) based algorithm for the real-time car-following status identification. The initial field test results have demonstrated the effectiveness of the proposed algorithms with the false alarm of 7.25% in the 10Hz output rate.
{"title":"Rear-End Collision detection based on GNSS/compass fusion and adaptive neuro fuzzy inference system","authors":"Rui Sun, D. Xue, Yucheng Zhang","doi":"10.1109/CPGPS.2017.8075138","DOIUrl":"https://doi.org/10.1109/CPGPS.2017.8075138","url":null,"abstract":"Rear-End Collision has been considered as one of the most frequent accidents on roadways. In recent years, Global Satellite Navigation System (GNSS) with the merit of flexible and low cost, has exhibited the great potential for the rear-end Collision Avoidance Systems (CAS) for vehicles. Nevertheless, two main issues associated with the current rear-end CAS are: 1) accessing to high accuracy vehicle relative positioning and dynamic parameters; and 2) the reliable method to extract the car-following status from such information. This paper has developed a novel GNSS/compass fusion with the Adaptive Neuro Fuzzy Inference System (ANFIS) based algorithm for the real-time car-following status identification. The initial field test results have demonstrated the effectiveness of the proposed algorithms with the false alarm of 7.25% in the 10Hz output rate.","PeriodicalId":340067,"journal":{"name":"2017 Forum on Cooperative Positioning and Service (CPGPS）","volume":"11 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":"116518505","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.2017.8075095
Shuai Chen, Zhen Shi, Jicheng Ding
This paper is focused on the application of 2nd-order Smooth Variable Structure Filter (SVSF) algorithm in the initial alignment of Strapdown Inertial Navigation System (SINS), which is used to achieve robust and precise alignment results in large azimuth misalignment angle. Normally, the SVSF method requires the system to be observable and controllable, motivated by this, a combined alignment structure is proposed based on the Kalman type filter alignment method and gyrocompass alignment method firstly and the 2nd-order SVSF method is used to estimate the misalignment angles in the process of the combined alignment. Compared to the conventional alignment estimation method, the simulation results show that the 2nd-order SVSF alignment method could gain a more stable and accurate misalignment angle.
{"title":"Application of the 2nd-order Smooth Variable Structure Filter algorithm for SINS initial alignment","authors":"Shuai Chen, Zhen Shi, Jicheng Ding","doi":"10.1109/CPGPS.2017.8075095","DOIUrl":"https://doi.org/10.1109/CPGPS.2017.8075095","url":null,"abstract":"This paper is focused on the application of 2nd-order Smooth Variable Structure Filter (SVSF) algorithm in the initial alignment of Strapdown Inertial Navigation System (SINS), which is used to achieve robust and precise alignment results in large azimuth misalignment angle. Normally, the SVSF method requires the system to be observable and controllable, motivated by this, a combined alignment structure is proposed based on the Kalman type filter alignment method and gyrocompass alignment method firstly and the 2nd-order SVSF method is used to estimate the misalignment angles in the process of the combined alignment. Compared to the conventional alignment estimation method, the simulation results show that the 2nd-order SVSF alignment method could gain a more stable and accurate misalignment angle.","PeriodicalId":340067,"journal":{"name":"2017 Forum on Cooperative Positioning and Service (CPGPS）","volume":"14 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":"126724889","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.2017.8075103
Yulong Kong, Hongzhou Chai, JinYao Li, Zongpeng Pan, Yang Chong
The ordinary ARMA forecast model uses the differential method to get the stationary ionosphere VTEC (Vertical Total Electron Content Unit) series. This paper proposes a new un-difference method to stabilize the VTEC time series. The superiority and reasonability of the new method is proved by comparing the result of two methods. Then, the un-difference predicting method is used to process the long series of IGS ionosphere VTEC products in this paper. By calculating the predicting result of the 263th day to 272th day from 2006 to 2015, this paper comes to conclusions that the predicting precision is higher during solar inactive years and lower during solar active years. The difference of the predicting precision can be used to distinguish the activity level of ionosphere.
{"title":"A modified forecast method of ionosphere VTEC series based on ARMA model","authors":"Yulong Kong, Hongzhou Chai, JinYao Li, Zongpeng Pan, Yang Chong","doi":"10.1109/CPGPS.2017.8075103","DOIUrl":"https://doi.org/10.1109/CPGPS.2017.8075103","url":null,"abstract":"The ordinary ARMA forecast model uses the differential method to get the stationary ionosphere VTEC (Vertical Total Electron Content Unit) series. This paper proposes a new un-difference method to stabilize the VTEC time series. The superiority and reasonability of the new method is proved by comparing the result of two methods. Then, the un-difference predicting method is used to process the long series of IGS ionosphere VTEC products in this paper. By calculating the predicting result of the 263th day to 272th day from 2006 to 2015, this paper comes to conclusions that the predicting precision is higher during solar inactive years and lower during solar active years. The difference of the predicting precision can be used to distinguish the activity level of ionosphere.","PeriodicalId":340067,"journal":{"name":"2017 Forum on Cooperative Positioning and Service (CPGPS）","volume":"58 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":"125159206","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.2017.8075131
Tianxia Liu, Bofeng Li
Technology of low-cost single-frequency RTK (real time kinematic) is booming in popular GNSS application, however, the poor data quality and hardware performance of low-cost receivers bring about great challenges to its positioning algorithm. In this contribution, a BDS/GPS single-frequency inexpensive navigation and positioning (SINAP) system is developed to achieve high-precise high-stability single-frequency RTK positioning with low-cost GNSS receivers. In data processing, we implement the Kalman filter estimation with constant velocity (CV) and constant acceleration (CA) dynamic models. Since it is not feasible to fix the whole integer ambiguities in real applications, we utilize the PAR (partial ambiguity resolution) method to acquire a subset of integer ambiguities effectively. Experiments with static and kinematic data were carried out by using low-cost single-frequency u-blox receivers. To emphasize the benefits of the proposed method, we compare the performance of SINAP to those of the open source software RTKLIB and the u-blox chip. It is shown that results of SINAP are competitive to the ones of u-blox and outperform the ones of RTKLIB. Moreover, the performance of GPS-only, BDS-only and combination of BDS/GPS are investigated. The results reveal that using BDS/GPS can achieve higher fix-rate and higher positioning accuracy than using GPS or BDS only. Additionally, with Kalman filter, we compare the CA and the CV dynamic models using kinematic data, which illustrates that both models can provide comparatively ideal results with no obvious difference.
{"title":"Single-frequency BDS/GPS RTK with low-cost U-blox receivers","authors":"Tianxia Liu, Bofeng Li","doi":"10.1109/CPGPS.2017.8075131","DOIUrl":"https://doi.org/10.1109/CPGPS.2017.8075131","url":null,"abstract":"Technology of low-cost single-frequency RTK (real time kinematic) is booming in popular GNSS application, however, the poor data quality and hardware performance of low-cost receivers bring about great challenges to its positioning algorithm. In this contribution, a BDS/GPS single-frequency inexpensive navigation and positioning (SINAP) system is developed to achieve high-precise high-stability single-frequency RTK positioning with low-cost GNSS receivers. In data processing, we implement the Kalman filter estimation with constant velocity (CV) and constant acceleration (CA) dynamic models. Since it is not feasible to fix the whole integer ambiguities in real applications, we utilize the PAR (partial ambiguity resolution) method to acquire a subset of integer ambiguities effectively. Experiments with static and kinematic data were carried out by using low-cost single-frequency u-blox receivers. To emphasize the benefits of the proposed method, we compare the performance of SINAP to those of the open source software RTKLIB and the u-blox chip. It is shown that results of SINAP are competitive to the ones of u-blox and outperform the ones of RTKLIB. Moreover, the performance of GPS-only, BDS-only and combination of BDS/GPS are investigated. The results reveal that using BDS/GPS can achieve higher fix-rate and higher positioning accuracy than using GPS or BDS only. Additionally, with Kalman filter, we compare the CA and the CV dynamic models using kinematic data, which illustrates that both models can provide comparatively ideal results with no obvious difference.","PeriodicalId":340067,"journal":{"name":"2017 Forum on Cooperative Positioning and Service (CPGPS）","volume":"119 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":"132970548","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.2017.8075130
Yanheng Wang, S. Pan, Ruicheng Zhang, H. Hu
The users of real time kinematic(RTK) still base on basic frequency carrier for ambiguity resolution(AR) and positioning, which leads to impossibility for positioning instantaneously. However, higher timeliness instead of precision by centimeter level is in high and increasing demand in some areas. Therefore, a method of single-epoch ambiguity resolution and positioning was researched in the paper. Firstly, (0,-1,1) extra-wide-lane(EWL) combination was fixed using Melbourne-Wübbena method. Then, (1,0,-1) wide-lane(WL) was fixed with aid of (0,-1,1). Finally, the performance of positioning with WL was tested. The test was conducted in the paper using a baseline of Jiangsu province Continuously Operating Reference Stations on 41.5km and a baseline in Huangpu district of Guangzhou City on 8km. The results showed that the success rate of single-epoch AR reached 99.9% and both horizontal and zenith direction were better than 30cm of 8km. And the success rate reached 99.9%, the horizontal direction was better than 25cm and the zenith direction was better than 35cm of 41.5km. The conclusion has been proved that the method would get great performance in AR in single-epoch of short-range and medium-range baseline and precision of positioning by decimeter level.
实时运动学(RTK)的用户仍然基于基频载波进行模糊度分辨(AR)和定位，这导致无法实现即时定位。然而，在某些领域，更高的及时性而不是厘米级精度的需求很高，而且还在不断增长。为此，本文研究了一种单历元模糊度分辨与定位方法。首先，采用melbourne - w bbena方法固定(0，-1,1)超宽车道(EWL)组合;然后，借助(0，-1,1)固定(1,0，-1)宽车道(WL)。最后，对WL定位的性能进行了测试。本文采用江苏省连续运行参考站41.5km基线和广州市黄浦区8km基线进行试验。结果表明，单历元AR成功率达99.9%，水平方向和天顶方向均优于30cm / 8km。41.5km的水平方向优于25cm，天顶方向优于35cm，成功率达99.9%。实验结果表明，该方法在单历元近程和中程基线条件下具有良好的AR性能和分米级定位精度。
{"title":"Single-epoch real-time differential positioning with BDS triple-frequency wide-lane combination","authors":"Yanheng Wang, S. Pan, Ruicheng Zhang, H. Hu","doi":"10.1109/CPGPS.2017.8075130","DOIUrl":"https://doi.org/10.1109/CPGPS.2017.8075130","url":null,"abstract":"The users of real time kinematic(RTK) still base on basic frequency carrier for ambiguity resolution(AR) and positioning, which leads to impossibility for positioning instantaneously. However, higher timeliness instead of precision by centimeter level is in high and increasing demand in some areas. Therefore, a method of single-epoch ambiguity resolution and positioning was researched in the paper. Firstly, (0,-1,1) extra-wide-lane(EWL) combination was fixed using Melbourne-Wübbena method. Then, (1,0,-1) wide-lane(WL) was fixed with aid of (0,-1,1). Finally, the performance of positioning with WL was tested. The test was conducted in the paper using a baseline of Jiangsu province Continuously Operating Reference Stations on 41.5km and a baseline in Huangpu district of Guangzhou City on 8km. The results showed that the success rate of single-epoch AR reached 99.9% and both horizontal and zenith direction were better than 30cm of 8km. And the success rate reached 99.9%, the horizontal direction was better than 25cm and the zenith direction was better than 35cm of 41.5km. The conclusion has been proved that the method would get great performance in AR in single-epoch of short-range and medium-range baseline and precision of positioning by decimeter level.","PeriodicalId":340067,"journal":{"name":"2017 Forum on Cooperative Positioning and Service (CPGPS）","volume":"41 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":"133446357","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.2017.8075097
Baoyu Liu, X. Zhan, Maolin Chen, Jinyu Liu
This paper presents a scheme for building a deeply coupled GNSS/INS software defined receiver based on Matlab. Two key issues involved, the “real-time” calculation and the alignment between GNSS IF data and IMU data, are elaborated in detail. The proposed software defined receiver has a pure software implementation; the only hardware for it is the front end. It is compatible with a variety of data sources and is able to give a complete simulation for the real deeply coupled GNSS/INS navigation system. Compared to the hardware platform based on DSP+FPGA, this proposed software defined receiver is more flexible and is more efficient for algorithm testing or development. A studied example is presented to show the usage and performance of the proposed software defined receiver.
{"title":"An approach for the deeply coupled GNSS/INS software defined receiver based on Matlab","authors":"Baoyu Liu, X. Zhan, Maolin Chen, Jinyu Liu","doi":"10.1109/CPGPS.2017.8075097","DOIUrl":"https://doi.org/10.1109/CPGPS.2017.8075097","url":null,"abstract":"This paper presents a scheme for building a deeply coupled GNSS/INS software defined receiver based on Matlab. Two key issues involved, the “real-time” calculation and the alignment between GNSS IF data and IMU data, are elaborated in detail. The proposed software defined receiver has a pure software implementation; the only hardware for it is the front end. It is compatible with a variety of data sources and is able to give a complete simulation for the real deeply coupled GNSS/INS navigation system. Compared to the hardware platform based on DSP+FPGA, this proposed software defined receiver is more flexible and is more efficient for algorithm testing or development. A studied example is presented to show the usage and performance of the proposed software defined receiver.","PeriodicalId":340067,"journal":{"name":"2017 Forum on Cooperative Positioning and Service (CPGPS）","volume":"27 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":"132944176","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.2017.8075113
Xiaolei Wang, Shuangcheng Zhang, Qin Zhang
Accurate and long-term monitoring of soil moisture is of great significance for global water and carbon cycles. The soil moisture variation estimated from GPS-IR (GPS-InterferometricReflectometry) overcomes some drawbacks of traditional ways, and has become an important topic. Changes in the permittivity of the soil, which are associated with fluctuations in soil moisture, affect the effective frequency, phase, and amplitude of signal-to-noise ratio (SNR) data recorded by the GPS receiver. This study used Fast Fourier Transform (FFT) algorithm with equal sinusoidal elevation angle-interval sampling and Least Square (LS) method mainly used in most previous studies to acquire GPS interferogram metrics, by comparing the retrievals with volumetric soil moisture retrieved by PBO H2O group. The values of frequency extracted by these two algorithms linearly and negatively correlate with surface soil moisture, showing correlations of −0.57 for LS and −0.45 for FFT. However, the correlation coefficient for phase extracted by FFT was 0.61, greater than that by LS of 0.31, both positively.
{"title":"Soil moisture variation estimated from GPS-IR using FFT and LS","authors":"Xiaolei Wang, Shuangcheng Zhang, Qin Zhang","doi":"10.1109/CPGPS.2017.8075113","DOIUrl":"https://doi.org/10.1109/CPGPS.2017.8075113","url":null,"abstract":"Accurate and long-term monitoring of soil moisture is of great significance for global water and carbon cycles. The soil moisture variation estimated from GPS-IR (GPS-InterferometricReflectometry) overcomes some drawbacks of traditional ways, and has become an important topic. Changes in the permittivity of the soil, which are associated with fluctuations in soil moisture, affect the effective frequency, phase, and amplitude of signal-to-noise ratio (SNR) data recorded by the GPS receiver. This study used Fast Fourier Transform (FFT) algorithm with equal sinusoidal elevation angle-interval sampling and Least Square (LS) method mainly used in most previous studies to acquire GPS interferogram metrics, by comparing the retrievals with volumetric soil moisture retrieved by PBO H2O group. The values of frequency extracted by these two algorithms linearly and negatively correlate with surface soil moisture, showing correlations of −0.57 for LS and −0.45 for FFT. However, the correlation coefficient for phase extracted by FFT was 0.61, greater than that by LS of 0.31, both positively.","PeriodicalId":340067,"journal":{"name":"2017 Forum on Cooperative Positioning and Service (CPGPS）","volume":"35 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":"132954232","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.2017.8075128
Guochao Zhang, Q. Gui, Songhui Han, Jun Zhao, Wenhua Huang
Based on the time series analysis method, this article develops a Bayesian method of detecting and repairing the cycle slips in the GNSS carrier-phase data. Firstly, this article analyses the characteristics of the cycle slips in the GNSS carrier-phase observations and establishes the relationships between the cycle slips and the additive outliers (AOs) in the stationary time series. When the ARMA (autoregressive moving-average) model is used to fit the stationary time series obtained by differencing the GNSS carrier-phase observations, the detection of cycle slips in the GNSS carrier-phase observations can be transformed to the detection of AOs in the ARMA model. Then, this article proposes a Bayesian method of detecting the AOs in the ARMA model, and the implementation of detecting the cycle slips in the GNSS carrier-phase observations is also developed. Finally, the new Bayesian method of detecting the cycle slips is used to the real GNSS carrier-phase data. From the comparison among the Bayesian method, the high-order differences method and ionospheric residual method, we can find that the Bayesian method has a better detection efficiency for several kinds of cycle slips in the GNSS carrier-phase observations than other methods.
{"title":"A Bayesian method of GNSS cycle slips detection based on ARMA model","authors":"Guochao Zhang, Q. Gui, Songhui Han, Jun Zhao, Wenhua Huang","doi":"10.1109/CPGPS.2017.8075128","DOIUrl":"https://doi.org/10.1109/CPGPS.2017.8075128","url":null,"abstract":"Based on the time series analysis method, this article develops a Bayesian method of detecting and repairing the cycle slips in the GNSS carrier-phase data. Firstly, this article analyses the characteristics of the cycle slips in the GNSS carrier-phase observations and establishes the relationships between the cycle slips and the additive outliers (AOs) in the stationary time series. When the ARMA (autoregressive moving-average) model is used to fit the stationary time series obtained by differencing the GNSS carrier-phase observations, the detection of cycle slips in the GNSS carrier-phase observations can be transformed to the detection of AOs in the ARMA model. Then, this article proposes a Bayesian method of detecting the AOs in the ARMA model, and the implementation of detecting the cycle slips in the GNSS carrier-phase observations is also developed. Finally, the new Bayesian method of detecting the cycle slips is used to the real GNSS carrier-phase data. From the comparison among the Bayesian method, the high-order differences method and ionospheric residual method, we can find that the Bayesian method has a better detection efficiency for several kinds of cycle slips in the GNSS carrier-phase observations than other methods.","PeriodicalId":340067,"journal":{"name":"2017 Forum on Cooperative Positioning and Service (CPGPS）","volume":"92 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":"133659564","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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