Conventional GNSS positioning algorithms rely on the assumption that the pseudo-range error follows a normal distribution, which allows for the use of statistical techniques and probabilistic models to improve the accuracy and reliability of the positioning solution. However, this assumption does not always hold true in practice, especially in urban environments where blocking, reflections, and other factors can significantly impact the quality of the GNSS signals and lead to errors that do not conform to a normal distribution. In this paper, an efficient NLOS mitigation algorithm is proposed to improve positioning performance in cities. It allows conventional least-squares ranging (LSR) and extended Kalman filtering (EKF) to handle asymmetric distributions and to determine an appropriate distribution for each measurement based on its signal strength. This algorithm can be implemented on any GNSS receiver with only a small increase in processing load, and it does not require any additional information or hardware. The experiments were conducted in 13 different locations alongside busy roads in the London Borough of Camden, where two 3-minute sessions of static pedestrian navigation data were collected at each location using a u-blox ZED-F9P GNSS receiver, one for training and the other for testing. The experimental results confirm that the pseudo-range error of the NLOS signal does not conform to a normal distribution. Compared to the conventional approaches, the proposed method was able to reduce the RMS horizontal position error by about 21% and 34% in the single and multi-epoch cases, respectively. The performance of the proposed method was also compared to 3D-mapping-aided (3DMA) GNSS positioning.
{"title":"Asymmetric Positioning for NLOS Mitigation","authors":"Qiming Zhong","doi":"10.33012/2023.19336","DOIUrl":"https://doi.org/10.33012/2023.19336","url":null,"abstract":"Conventional GNSS positioning algorithms rely on the assumption that the pseudo-range error follows a normal distribution, which allows for the use of statistical techniques and probabilistic models to improve the accuracy and reliability of the positioning solution. However, this assumption does not always hold true in practice, especially in urban environments where blocking, reflections, and other factors can significantly impact the quality of the GNSS signals and lead to errors that do not conform to a normal distribution. In this paper, an efficient NLOS mitigation algorithm is proposed to improve positioning performance in cities. It allows conventional least-squares ranging (LSR) and extended Kalman filtering (EKF) to handle asymmetric distributions and to determine an appropriate distribution for each measurement based on its signal strength. This algorithm can be implemented on any GNSS receiver with only a small increase in processing load, and it does not require any additional information or hardware. The experiments were conducted in 13 different locations alongside busy roads in the London Borough of Camden, where two 3-minute sessions of static pedestrian navigation data were collected at each location using a u-blox ZED-F9P GNSS receiver, one for training and the other for testing. The experimental results confirm that the pseudo-range error of the NLOS signal does not conform to a normal distribution. Compared to the conventional approaches, the proposed method was able to reduce the RMS horizontal position error by about 21% and 34% in the single and multi-epoch cases, respectively. The performance of the proposed method was also compared to 3D-mapping-aided (3DMA) GNSS positioning.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"301 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135483681","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}
WiFi has vast infrastructure presence making it an ideal candidate for mobile indoor positioning. WiFi Fine Time Measurement (FTM), is a WiFi protocol that enables the time of flight (ToF) of a WiFi signal to be determined; referred to as WiFi Round Trip Timing (RTT). Providing a ToF based protocol has allowed ToF based positioning algorithms to be applied to WiFi signals which could provide an improvement over the current RSSI-fingerprinting state of the art. Non line of sight (NLOS) reception and multipath interference degrade WiFi RTT accuracy. The research in this paper explores the accuracy of WiFi RTT positioning in a variety of indoor environments by utilising filtering techniques and RSSI-based outlier detection. Four positioning algorithms are explored: Least squares, a particle filter, a genetic filter and a grid filter. 67% of trials resulted in sub-metre accuracy and 90.5% of trials had a RMSE below 2m, the accuracy was worst in environments with NLOS conditions where 38% of trials resulted in sub-metre accuracy whereas for environments with complete LOS conditions 95.2% of trials resulted in sub-metre accuracy. A method to mitigate NLOS error is RSSI-based outlier detection, this method detects anomalies between the RSSI and the measured RTT range and de-weights anomalous signals during filtering. This outlier detection performed well in environments with NLOS conditions, at its best providing an average improvement of 41.3% over no outlier detection across all algorithms in an environment. The Genetic Filter performed best overall with a mean improvement of 49.2% when compared to least squares, the particle filter performed achieved an average of 38%. For the particle filter, this can be attributed to poorer mitigation of particle degeneracy. The genetic filter was also the only algorithm to provide a performance improvement over least squares in all environments.
WiFi拥有广泛的基础设施，使其成为室内移动定位的理想选择。WiFi Fine Time Measurement (FTM)，是一种WiFi协议，可以确定WiFi信号的飞行时间(ToF);被称为WiFi往返计时(RTT)。提供基于ToF的协议允许基于ToF的定位算法应用于WiFi信号，这可能比当前的rssi指纹识别技术提供改进。非视距(NLOS)接收和多径干扰会降低WiFi RTT精度。本文研究利用滤波技术和基于rssi的离群点检测，探讨了WiFi RTT在各种室内环境下的定位精度。研究了四种定位算法:最小二乘、粒子滤波、遗传滤波和网格滤波。67%的试验导致亚米精度，90.5%的试验RMSE低于2m，在NLOS条件下的精度最差，其中38%的试验导致亚米精度，而在完全LOS条件下的环境中，95.2%的试验导致亚米精度。一种减轻NLOS误差的方法是基于RSSI的离群值检测，该方法检测RSSI与测量RTT范围之间的异常，并在滤波过程中对异常信号进行去权重处理。这种离群值检测在具有NLOS条件的环境中表现良好，在最佳情况下，在一个环境中的所有算法中，与没有离群值检测相比，平均提高41.3%。与最小二乘法相比，遗传滤波器的平均改进率为49.2%，粒子滤波器的平均改进率为38%。对于粒子滤波器，这可归因于较差的粒子退化缓解。遗传滤波器也是在所有环境中提供比最小二乘性能改进的唯一算法。
{"title":"WiFi-RTT Indoor Positioning Using Particle, Genetic and Grid Filters with RSSI-Based Outlier Detection","authors":"K. Jibran Raja, Paul D. Groves","doi":"10.33012/2023.19211","DOIUrl":"https://doi.org/10.33012/2023.19211","url":null,"abstract":"WiFi has vast infrastructure presence making it an ideal candidate for mobile indoor positioning. WiFi Fine Time Measurement (FTM), is a WiFi protocol that enables the time of flight (ToF) of a WiFi signal to be determined; referred to as WiFi Round Trip Timing (RTT). Providing a ToF based protocol has allowed ToF based positioning algorithms to be applied to WiFi signals which could provide an improvement over the current RSSI-fingerprinting state of the art. Non line of sight (NLOS) reception and multipath interference degrade WiFi RTT accuracy. The research in this paper explores the accuracy of WiFi RTT positioning in a variety of indoor environments by utilising filtering techniques and RSSI-based outlier detection. Four positioning algorithms are explored: Least squares, a particle filter, a genetic filter and a grid filter. 67% of trials resulted in sub-metre accuracy and 90.5% of trials had a RMSE below 2m, the accuracy was worst in environments with NLOS conditions where 38% of trials resulted in sub-metre accuracy whereas for environments with complete LOS conditions 95.2% of trials resulted in sub-metre accuracy. A method to mitigate NLOS error is RSSI-based outlier detection, this method detects anomalies between the RSSI and the measured RTT range and de-weights anomalous signals during filtering. This outlier detection performed well in environments with NLOS conditions, at its best providing an average improvement of 41.3% over no outlier detection across all algorithms in an environment. The Genetic Filter performed best overall with a mean improvement of 49.2% when compared to least squares, the particle filter performed achieved an average of 38%. For the particle filter, this can be attributed to poorer mitigation of particle degeneracy. The genetic filter was also the only algorithm to provide a performance improvement over least squares in all environments.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135483682","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}
This work proposes a new method for detecting ionospheric activity in the context of future dual-frequency Ground Based Augmentation Systems (GBAS). We utilize measurements available to an airborne GBAS user to derive a probability for large anomalous ionospheric gradients currently present between the aircraft and the local GBAS station. For this purpose, two metrics in satellite range domain are introduced for activity detection: the first is based on the total ionospheric delay difference between ground and air and the second one uses a cumulative sum (CUSUM) based monitoring approach of the rate of change of ionospheric delay difference estimates. After introducing the new concept for this ionospheric activity monitoring, we explain the design parameters that influence the sensitivity of the test and how they can be adjusted. Based on a large simulation dataset, we evaluate the detection capability of the new approach and subsequently the potential to reduce the ionospheric protection levels under nominal conditions by ensuring the absence of harmful ionospheric disturbances. Finally, the monitoring is applied to a measurement dataset within an experimental GBAS facility to evaluate the potential to improve monitor performance and thus improve nominal availability in the presence of significant local multipath. Overall, the results indicate the potential to improve system availability, especially in situations where few satellites are available, such as when using a single constellation, while being able to detect ionospheric activity before the onset of harmful errors for an airborne GBAS user on approach.
{"title":"Adaptive Airborne Ionospheric Gradient Monitoring for Dual-Frequency GBAS","authors":"Daniel Gerbeth, Maria Caamano","doi":"10.33012/2023.19268","DOIUrl":"https://doi.org/10.33012/2023.19268","url":null,"abstract":"This work proposes a new method for detecting ionospheric activity in the context of future dual-frequency Ground Based Augmentation Systems (GBAS). We utilize measurements available to an airborne GBAS user to derive a probability for large anomalous ionospheric gradients currently present between the aircraft and the local GBAS station. For this purpose, two metrics in satellite range domain are introduced for activity detection: the first is based on the total ionospheric delay difference between ground and air and the second one uses a cumulative sum (CUSUM) based monitoring approach of the rate of change of ionospheric delay difference estimates. After introducing the new concept for this ionospheric activity monitoring, we explain the design parameters that influence the sensitivity of the test and how they can be adjusted. Based on a large simulation dataset, we evaluate the detection capability of the new approach and subsequently the potential to reduce the ionospheric protection levels under nominal conditions by ensuring the absence of harmful ionospheric disturbances. Finally, the monitoring is applied to a measurement dataset within an experimental GBAS facility to evaluate the potential to improve monitor performance and thus improve nominal availability in the presence of significant local multipath. Overall, the results indicate the potential to improve system availability, especially in situations where few satellites are available, such as when using a single constellation, while being able to detect ionospheric activity before the onset of harmful errors for an airborne GBAS user on approach.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135483692","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}
W. Jacob Wagner, Isaac Blankenau, Maribel DeLaTorre, Amartya Purushottam, Ahmet Soylemezoglu
This work addresses the challenge of developing a localization system for an uncrewed ground vehicle (UGV) operating autonomously in unstructured outdoor Global Navigation Satellite System (GNSS)-denied environments. The goal is to enable accurate mapping and long-range navigation with practical applications in domains such as autonomous construction, military engineering missions, and exploration of non-Earth planets. The proposed system - Terrain-Referenced Assured Engineer Localization System (TRAELS) – integrates pose estimates produced by two complementary terrain referenced navigation (TRN) methods with wheel odometry and inertial measurement unit (IMU) measurements using an Extended Kalman Filter (EKF). Unlike simultaneous localization and mapping (SLAM) systems that require loop closures, the described approach maintains accuracy over long distances and one-way missions without the need to revisit previous positions. Evaluation of TRAELS is performed across a range of environments. In regions where a combination of distinctive geometric and ground surface features are present, the developed TRN methods are leveraged by TRAELS to consistently achieve an absolute trajectory error of less than 3.0 m. The approach is also shown to be capable of recovering from large accumulated drift when traversing feature-sparse areas, which is essential in ensuring robust performance of the system across a wide variety of challenging GNSS-denied environments. Overall, the effectiveness of the system in providing precise localization and mapping capabilities in challenging GNSS-denied environments is demonstrated and an analysis is performed leading to insights for improving TRN approaches for UGVs.
{"title":"A Robust Localization Solution for an Uncrewed Ground Vehicle in Unstructured Outdoor GNSS-Denied Environments","authors":"W. Jacob Wagner, Isaac Blankenau, Maribel DeLaTorre, Amartya Purushottam, Ahmet Soylemezoglu","doi":"10.33012/2023.19412","DOIUrl":"https://doi.org/10.33012/2023.19412","url":null,"abstract":"This work addresses the challenge of developing a localization system for an uncrewed ground vehicle (UGV) operating autonomously in unstructured outdoor Global Navigation Satellite System (GNSS)-denied environments. The goal is to enable accurate mapping and long-range navigation with practical applications in domains such as autonomous construction, military engineering missions, and exploration of non-Earth planets. The proposed system - Terrain-Referenced Assured Engineer Localization System (TRAELS) – integrates pose estimates produced by two complementary terrain referenced navigation (TRN) methods with wheel odometry and inertial measurement unit (IMU) measurements using an Extended Kalman Filter (EKF). Unlike simultaneous localization and mapping (SLAM) systems that require loop closures, the described approach maintains accuracy over long distances and one-way missions without the need to revisit previous positions. Evaluation of TRAELS is performed across a range of environments. In regions where a combination of distinctive geometric and ground surface features are present, the developed TRN methods are leveraged by TRAELS to consistently achieve an absolute trajectory error of less than 3.0 m. The approach is also shown to be capable of recovering from large accumulated drift when traversing feature-sparse areas, which is essential in ensuring robust performance of the system across a wide variety of challenging GNSS-denied environments. Overall, the effectiveness of the system in providing precise localization and mapping capabilities in challenging GNSS-denied environments is demonstrated and an analysis is performed leading to insights for improving TRN approaches for UGVs.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135483708","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}
Numerous methods have been proposed for global navigation satellite system (GNSS) receivers to detect faulty GNSS signals. One such fault detection and exclusion (FDE) method is based on the mathematical concept of Euclidean distance matrices (EDMs). This paper outlines a greedy approach that uses an improved Euclidean distance matrix-based fault detection and exclusion algorithm. The novel greedy EDM FDE method implements a new fault detection test statistic and fault exclusion strategy that drastically simplifies the complexity of the algorithm over previous work. To validate the novel greedy EDM FDE algorithm, we created a simulated dataset using receiver locations from around the globe. The simulated dataset allows us to verify our results on 2,601 different satellite geometries. The Python implementation of the greedy EDM FDE algorithm is shown to be computed much more rapidly than a comparable greedy residual FDE method while obtaining similar fault exclusion accuracy. We provide discussion on the comparative time complexities of greedy EDM FDE and greedy residual FDE. We also explain common modifications to greedy residual FDE that can also be added to greedy EDM FDE to alter performance characteristics.
{"title":"Detection and Exclusion of Multiple Faults using Euclidean Distance Matrices","authors":"Derek Knowles, Grace Gao","doi":"10.33012/2023.19280","DOIUrl":"https://doi.org/10.33012/2023.19280","url":null,"abstract":"Numerous methods have been proposed for global navigation satellite system (GNSS) receivers to detect faulty GNSS signals. One such fault detection and exclusion (FDE) method is based on the mathematical concept of Euclidean distance matrices (EDMs). This paper outlines a greedy approach that uses an improved Euclidean distance matrix-based fault detection and exclusion algorithm. The novel greedy EDM FDE method implements a new fault detection test statistic and fault exclusion strategy that drastically simplifies the complexity of the algorithm over previous work. To validate the novel greedy EDM FDE algorithm, we created a simulated dataset using receiver locations from around the globe. The simulated dataset allows us to verify our results on 2,601 different satellite geometries. The Python implementation of the greedy EDM FDE algorithm is shown to be computed much more rapidly than a comparable greedy residual FDE method while obtaining similar fault exclusion accuracy. We provide discussion on the comparative time complexities of greedy EDM FDE and greedy residual FDE. We also explain common modifications to greedy residual FDE that can also be added to greedy EDM FDE to alter performance characteristics.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135483910","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}
Autonomous multi-agent systems similar to NASA’s CADRE mission could substantially improve the efficiency of robotic exploration on other planets. However, communication challenges pose a large risk to two main capabilities: collision avoidance and active collaborative localization. This work expands on Reachability-based Trajectory Design (RTD), intent prediction, and fault-based planning to develop an approach that improves the robustness of these capabilities under communication loss scenarios. This approach is then validated on turtlebots simulated in Gazebo.
{"title":"Intent- and Fault-based Trajectory Prediction for Cooperative Localization and Collision Avoidance in Swarms","authors":"Isabella Torres, Grace Gao","doi":"10.33012/2023.19470","DOIUrl":"https://doi.org/10.33012/2023.19470","url":null,"abstract":"Autonomous multi-agent systems similar to NASA’s CADRE mission could substantially improve the efficiency of robotic exploration on other planets. However, communication challenges pose a large risk to two main capabilities: collision avoidance and active collaborative localization. This work expands on Reachability-based Trajectory Design (RTD), intent prediction, and fault-based planning to develop an approach that improves the robustness of these capabilities under communication loss scenarios. This approach is then validated on turtlebots simulated in Gazebo.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"439 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135483917","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}
Philipp Rudnik, Lothar Kurz, Andreas Winterstein, Manuel Cuntz
The multi-antenna Global Navigation Satellite System (GNSS) receiver GALileo ANTenna (GALANT) has been developed at German Aerospace Center (DLR) since several years. Recently, effort has been spent to miniaturize the antennas and digital processing system in order to enable applications in the field of Unmanned Aerial Vehicle (UAV) navigation for example. In addition, array processing technologies have been further improved for this kind of application. This publication focuses on the conduction of flight test of the complete system and the therein occurring advantages towards a commercial receiver in difficult navigation scenarios like under the influence of jamming. The flight experiments are divided into two parts. Firstly, it is investigated how the different receivers react to corresponding jamming from the ground while the receiver is not moving, but is hovering close to the ground. During this experiment, the jamming power is increased step by step. The reference receiver goes into saturation, gradually loses all satellites, the position accuracy drops and finally no valid Position/Velocity/Timing (PVT) can be computed. In contrast, the GALANT receiver detects the interference and suppresses it appropriately based on spatial signal processing techniques. In the second part of the experiments, it is investigated how jamming signals emitted from ground affect the receiver during real flight scenarios. A static and directional jammer is set up and the UAV flies a trajectory passing multiple times through the beam. Interestingly the reference receiver does not only lose all satellites in track, like expected from the first experiment, but computes a false position increasingly diverging from ground truth before and after the total loss. The deviation of position is in the range of multiple hundred meters. The GALANT receiver is able to keep most of the satellites in track, and computes a continuous position with negligible deviation. The flight experiments conducted show that it is reasonable to protect UAVs appropriately against interference such as jamming. The tests also show that techniques, such as those presented, can be an effective solution to the stated problems. The developed robust, multi-antenna receiver outperformed the corresponding comparison receiver in the presented areas.
{"title":"Advantages of a Robust Multi-Antenna GNSS Receiver in UAV Flight Jamming Scenarios","authors":"Philipp Rudnik, Lothar Kurz, Andreas Winterstein, Manuel Cuntz","doi":"10.33012/2023.19378","DOIUrl":"https://doi.org/10.33012/2023.19378","url":null,"abstract":"The multi-antenna Global Navigation Satellite System (GNSS) receiver GALileo ANTenna (GALANT) has been developed at German Aerospace Center (DLR) since several years. Recently, effort has been spent to miniaturize the antennas and digital processing system in order to enable applications in the field of Unmanned Aerial Vehicle (UAV) navigation for example. In addition, array processing technologies have been further improved for this kind of application. This publication focuses on the conduction of flight test of the complete system and the therein occurring advantages towards a commercial receiver in difficult navigation scenarios like under the influence of jamming. The flight experiments are divided into two parts. Firstly, it is investigated how the different receivers react to corresponding jamming from the ground while the receiver is not moving, but is hovering close to the ground. During this experiment, the jamming power is increased step by step. The reference receiver goes into saturation, gradually loses all satellites, the position accuracy drops and finally no valid Position/Velocity/Timing (PVT) can be computed. In contrast, the GALANT receiver detects the interference and suppresses it appropriately based on spatial signal processing techniques. In the second part of the experiments, it is investigated how jamming signals emitted from ground affect the receiver during real flight scenarios. A static and directional jammer is set up and the UAV flies a trajectory passing multiple times through the beam. Interestingly the reference receiver does not only lose all satellites in track, like expected from the first experiment, but computes a false position increasingly diverging from ground truth before and after the total loss. The deviation of position is in the range of multiple hundred meters. The GALANT receiver is able to keep most of the satellites in track, and computes a continuous position with negligible deviation. The flight experiments conducted show that it is reasonable to protect UAVs appropriately against interference such as jamming. The tests also show that techniques, such as those presented, can be an effective solution to the stated problems. The developed robust, multi-antenna receiver outperformed the corresponding comparison receiver in the presented areas.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135483983","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}
Syed Ali Kazim, Juliette Marais, Nourdine Aït Tmazirte
Radio frequency interferences (RFIs) pose a severe threat to the Global Navigation Satellite System (GNSS). It is one of the main concerns that continue to challenge GNSS deployment in safety-related applications. Adaptive Notch Filter (ANF) is a classical method often used for the suppression of chirp signals. However, ANF performance is conditioned to the parameters selection where an inappropriate choice could also have a negative consequence. The adaptation step and pole contraction factor are mostly the two important parameters controlling the filter dynamics and suppression level. An appropriate compromise is needed while keeping in view the characteristics of the chirp signal. This study proposes a parameterization approach for ANF while dealing with a wide range of chirp signals with different values of sweep bandwidth, sweep rate, and power level. To provide labels RMSE criterion is investigated at the signal level before the de-spreading process. Finally, a generalized multivariate polynomial regression (MPR) model is presented that takes sweep bandwidth, sweep rate and power level as input features and predicts the values of the pole contraction factor and adaptation step. To validate the performance of ANF with the predictions, three scenarios with different chirp signals exhibiting slow, moderate and fast variations are presented. The mitigation performance is analyzed on several levels including, interference frequency estimation, satellite signal tracking, carrier-to-noise ratio and most importantly positioning KPIs such as accuracy, availability and safety.
{"title":"On the Parameterization of Single Pole Adaptive Notch Filter Against Wide Range of Linear Chirp Interference","authors":"Syed Ali Kazim, Juliette Marais, Nourdine Aït Tmazirte","doi":"10.33012/2023.19390","DOIUrl":"https://doi.org/10.33012/2023.19390","url":null,"abstract":"Radio frequency interferences (RFIs) pose a severe threat to the Global Navigation Satellite System (GNSS). It is one of the main concerns that continue to challenge GNSS deployment in safety-related applications. Adaptive Notch Filter (ANF) is a classical method often used for the suppression of chirp signals. However, ANF performance is conditioned to the parameters selection where an inappropriate choice could also have a negative consequence. The adaptation step and pole contraction factor are mostly the two important parameters controlling the filter dynamics and suppression level. An appropriate compromise is needed while keeping in view the characteristics of the chirp signal. This study proposes a parameterization approach for ANF while dealing with a wide range of chirp signals with different values of sweep bandwidth, sweep rate, and power level. To provide labels RMSE criterion is investigated at the signal level before the de-spreading process. Finally, a generalized multivariate polynomial regression (MPR) model is presented that takes sweep bandwidth, sweep rate and power level as input features and predicts the values of the pole contraction factor and adaptation step. To validate the performance of ANF with the predictions, three scenarios with different chirp signals exhibiting slow, moderate and fast variations are presented. The mitigation performance is analyzed on several levels including, interference frequency estimation, satellite signal tracking, carrier-to-noise ratio and most importantly positioning KPIs such as accuracy, availability and safety.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135483989","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}
Francesco Darugna, Temmo Wübbena, Gerhard Wübbena, Henning Albers, Jannes B. Wübbena
Airborne gravimetry is an alternative to traditional ground measurements for difficultly accessible areas like mountains or deserts and provides a valuable tool to link ground and satellite gravity measurements. In such applications, one of the main challenges is to separate the gravitational from the kinematic acceleration. As the vertical kinematic acceleration is the second derivative of the ellipsoidal height, it is typically estimated by GNSS-based positioning. Recent developments in the field of absolute quantum gravimetry will be part of the German Absolute Aero Quantengravimetrie (AeroQGrav) initiative. The AeroQGrav concept includes the fusion of multiple sensors to recover the gravity signal, aiming for resolutions of about 1 µm/s2 . The position of the gravimeter will mainly be estimated by a differential multi-frequency and multi-GNSS evaluation. Strongly correlated with the height of the computed position is the estimation of the tropospheric delay. Current differential GNSS positioning techniques rely on ground-based reference stations to provide accurate a priori tropospheric error estimates. These approaches are not sufficient for airborne gravity measurements as the altitude of reference stations and aircraft might differ significantly. Here, we suggest improving the a priori troposphere error information by utilizing numerical weather models (NWMs) with a high vertical resolution. A ray-tracing technique is implemented to compute the NWM-based satellite-dependent mapping functions to project the zenith delay onto the line of sight between the GNSS satellite and the receiver. The NWM-based tropospheric products are compared to GNSS-estimated delays. Finally, the benefits of adopting a NWM-based a priori model and NWM-enhanced mapping functions are evaluated in a precise point positioning (PPP) application. Results with and without using the a priori information and NWM-based mapping functions are compared and discussed in the context of the aircraft positioning for airborne quantum gravimetry to provide the rover algorithm with the best tropospheric delay possible.
{"title":"Improving GNSS-Based Tropospheric Delay Estimation for Airborne Quantum Gravimetry: First Results Using NWM Forecasting","authors":"Francesco Darugna, Temmo Wübbena, Gerhard Wübbena, Henning Albers, Jannes B. Wübbena","doi":"10.33012/2023.19266","DOIUrl":"https://doi.org/10.33012/2023.19266","url":null,"abstract":"Airborne gravimetry is an alternative to traditional ground measurements for difficultly accessible areas like mountains or deserts and provides a valuable tool to link ground and satellite gravity measurements. In such applications, one of the main challenges is to separate the gravitational from the kinematic acceleration. As the vertical kinematic acceleration is the second derivative of the ellipsoidal height, it is typically estimated by GNSS-based positioning. Recent developments in the field of absolute quantum gravimetry will be part of the German Absolute Aero Quantengravimetrie (AeroQGrav) initiative. The AeroQGrav concept includes the fusion of multiple sensors to recover the gravity signal, aiming for resolutions of about 1 µm/s2 . The position of the gravimeter will mainly be estimated by a differential multi-frequency and multi-GNSS evaluation. Strongly correlated with the height of the computed position is the estimation of the tropospheric delay. Current differential GNSS positioning techniques rely on ground-based reference stations to provide accurate a priori tropospheric error estimates. These approaches are not sufficient for airborne gravity measurements as the altitude of reference stations and aircraft might differ significantly. Here, we suggest improving the a priori troposphere error information by utilizing numerical weather models (NWMs) with a high vertical resolution. A ray-tracing technique is implemented to compute the NWM-based satellite-dependent mapping functions to project the zenith delay onto the line of sight between the GNSS satellite and the receiver. The NWM-based tropospheric products are compared to GNSS-estimated delays. Finally, the benefits of adopting a NWM-based a priori model and NWM-enhanced mapping functions are evaluated in a precise point positioning (PPP) application. Results with and without using the a priori information and NWM-based mapping functions are compared and discussed in the context of the aircraft positioning for airborne quantum gravimetry to provide the rover algorithm with the best tropospheric delay possible.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135484034","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}
Carlos Catalán Catalán, Luis García Iglesias, Andrés Juez Muñoz, Eduardo Fernández Matamala, César Pisonero Berges, Adrián Monreal Moreno, Mar Paüls Gassió, Eric Arnal Fort, María D. Laínez Samper, Jon Bruno Álvarez, José Caro Ramón
Leveraged by LEO (Low Earth Orbit) mega constellations deployed in recent times for communications, LEO PNT (Positioning, Navigation and Timing) has raised a high interest worldwide. Current integrity augmentations such as Space Based Augmentation Systems cannot provide time to alarms (TTAs) shorter than 6 seconds and rely on complex dedicated ground segments. The usage of the planned LEO mega constellations is investigated to implement an Integrity Monitor for a future Integrity Concept for the European Global Navigation Satellite System (EGNSS) high accuracy focused on automotive users with no intervention of a ground segment and with minimal capabilities on board of the satellite. The selected solution for the Integrity Monitor relies solely on a GNSS receiver on board of each LEO for collecting MEO-LEO observables and a communications link to the user for relaying this data, potentially in the same L-band. The user combines this information from the different LEOs in view and implements locally an Integrity Monitor. The Integrity Monitor checks individually each MEO against the Failure Modes allocated according to the Fault Tree Analysis (FTA) of the Integrity Concept. This study addresses generic failure modes such as satellite clock events or pseudorange errors. Service Volume Simulations are presented to demonstrate the feasibility of the proposed solution based on existing on-board GNSS receivers’ features and the future LEO mega constellations.
{"title":"Integrity Monitoring of GNSS with LEO Satellites to Reduce the Time to Alarm","authors":"Carlos Catalán Catalán, Luis García Iglesias, Andrés Juez Muñoz, Eduardo Fernández Matamala, César Pisonero Berges, Adrián Monreal Moreno, Mar Paüls Gassió, Eric Arnal Fort, María D. Laínez Samper, Jon Bruno Álvarez, José Caro Ramón","doi":"10.33012/2023.19460","DOIUrl":"https://doi.org/10.33012/2023.19460","url":null,"abstract":"Leveraged by LEO (Low Earth Orbit) mega constellations deployed in recent times for communications, LEO PNT (Positioning, Navigation and Timing) has raised a high interest worldwide. Current integrity augmentations such as Space Based Augmentation Systems cannot provide time to alarms (TTAs) shorter than 6 seconds and rely on complex dedicated ground segments. The usage of the planned LEO mega constellations is investigated to implement an Integrity Monitor for a future Integrity Concept for the European Global Navigation Satellite System (EGNSS) high accuracy focused on automotive users with no intervention of a ground segment and with minimal capabilities on board of the satellite. The selected solution for the Integrity Monitor relies solely on a GNSS receiver on board of each LEO for collecting MEO-LEO observables and a communications link to the user for relaying this data, potentially in the same L-band. The user combines this information from the different LEOs in view and implements locally an Integrity Monitor. The Integrity Monitor checks individually each MEO against the Failure Modes allocated according to the Fault Tree Analysis (FTA) of the Integrity Concept. This study addresses generic failure modes such as satellite clock events or pseudorange errors. Service Volume Simulations are presented to demonstrate the feasibility of the proposed solution based on existing on-board GNSS receivers’ features and the future LEO mega constellations.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135484048","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：