Brodie Wallace, Scott Palo, Penina Axelrad, John Marino, Nicholas Rainville, Ryan Kingsbury, Julia DiTomas, Mazen Shihabi, Dennis Ogbe
Interest in the Moon has grown significantly over the past few years as NASA works to return astronauts to the lunar surface. Historically, lunar missions have primarily been supported by Earth-based ground stations for communication and radionavigation. However, the quantity and scope of proposed lunar exploration, science, and commercial missions require in-situ infrastructure for continuous communication support and precision navigation services. We propose a lunar surface-based Position, Navigation, and Timing (PNT) and emergency broadcast pseudolite system as a cost-effective solution to support regional operations over exploration critical areas, and have previously explored architecture design characteristics, defined the pseudolite concept of operations, and identified potential navigation performance. This research is focused on developing a lunar pseudolite testbed with two primary objectives: demonstrating lunar surface communication and radionavigation techniques and characterizing the performance of low-cost, commercially available radio frequency (RF) hardware alternatives for supporting lunar operations. The work is comprised of four primary phases: (1) integration of the terrestrial pseudolite testbed, (2) development and testing of the communication and radionavigation protocols in a benchtop environment, (3) characterizing the relative range and time synchronization performance with different reference oscillators, and (4) over-the-air demonstrations with multiple pseudolite units. Pseudorandom noise (PRN) code ranging is the baseline relative positioning methodology, with signal tracking, range estimation, and absolute position estimates obtained by modifying open-source Global Navigation Satellite System (GNSS) software engines. Hardware tests were conducted to characterize the ranging performance, with average range error of less than 1.3 meters, primarily driven by time synchronization offsets. Initial tests demonstrate how low SWaP pseudolites can provide communication coverage and < 10 m error absolute positioning accuracy over critical lunar regions, helping to jumpstart exploration and commercialization on the lunar surface.
{"title":"Development of a Lunar Surface Navigation Pseudolite Testbed","authors":"Brodie Wallace, Scott Palo, Penina Axelrad, John Marino, Nicholas Rainville, Ryan Kingsbury, Julia DiTomas, Mazen Shihabi, Dennis Ogbe","doi":"10.33012/2023.19275","DOIUrl":"https://doi.org/10.33012/2023.19275","url":null,"abstract":"Interest in the Moon has grown significantly over the past few years as NASA works to return astronauts to the lunar surface. Historically, lunar missions have primarily been supported by Earth-based ground stations for communication and radionavigation. However, the quantity and scope of proposed lunar exploration, science, and commercial missions require in-situ infrastructure for continuous communication support and precision navigation services. We propose a lunar surface-based Position, Navigation, and Timing (PNT) and emergency broadcast pseudolite system as a cost-effective solution to support regional operations over exploration critical areas, and have previously explored architecture design characteristics, defined the pseudolite concept of operations, and identified potential navigation performance. This research is focused on developing a lunar pseudolite testbed with two primary objectives: demonstrating lunar surface communication and radionavigation techniques and characterizing the performance of low-cost, commercially available radio frequency (RF) hardware alternatives for supporting lunar operations. The work is comprised of four primary phases: (1) integration of the terrestrial pseudolite testbed, (2) development and testing of the communication and radionavigation protocols in a benchtop environment, (3) characterizing the relative range and time synchronization performance with different reference oscillators, and (4) over-the-air demonstrations with multiple pseudolite units. Pseudorandom noise (PRN) code ranging is the baseline relative positioning methodology, with signal tracking, range estimation, and absolute position estimates obtained by modifying open-source Global Navigation Satellite System (GNSS) software engines. Hardware tests were conducted to characterize the ranging performance, with average range error of less than 1.3 meters, primarily driven by time synchronization offsets. Initial tests demonstrate how low SWaP pseudolites can provide communication coverage and < 10 m error absolute positioning accuracy over critical lunar regions, helping to jumpstart exploration and commercialization on the lunar surface.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"49 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":"135483473","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}
Global Navigation Satellite System (GNSS) receivers are vulnerable to intentional radio frequency interferences, posing significant risks to their performance and reliability. Among these threats, it has been widely argued that modern GNSS-equipped Android™ smartphones are resilient to non-coherent spoofing attacks. This study challenges such a perception by highlighting the vulnerability of GNSS-equipped Android™ smartphones to single-antenna, non-coherent spoofing attacks and proposing a novel, application-level detection technique solely based on raw GNSS observables, i.e., carrier-to-noise-density time series. The analysis demonstrated the capability of successfully detecting such attacks by observing the cross-correlation among Global Navigation Satellite System (GNSS) measurements time series. Cross-correlation quantified by Pearson’s correlation coefficients shows a relevant increment during harmful spoofing attacks. Under these conditions, the proposed methodology allows to rise a spoofing alarm in about 5 seconds with a false alarm probability of 1.5%. Furthermore, the proposed technique does not require low-level signal access, making it suitable for implementation at the application layer in a large number of smart devices with limited knowledge of their low-level system architecture. A validation campaign has been performed by testing 18 different Android™ devices and chipsets, thus demonstrating the applicability of the proposed method independently from the device under test.
{"title":"Detecting Single-Antenna Spoofing Attacks by Correlation in Time Series of Raw Measurements","authors":"Alex Minetto, Akmal Rustamov, Fabio Dovis","doi":"10.33012/2023.19205","DOIUrl":"https://doi.org/10.33012/2023.19205","url":null,"abstract":"Global Navigation Satellite System (GNSS) receivers are vulnerable to intentional radio frequency interferences, posing significant risks to their performance and reliability. Among these threats, it has been widely argued that modern GNSS-equipped Android™ smartphones are resilient to non-coherent spoofing attacks. This study challenges such a perception by highlighting the vulnerability of GNSS-equipped Android™ smartphones to single-antenna, non-coherent spoofing attacks and proposing a novel, application-level detection technique solely based on raw GNSS observables, i.e., carrier-to-noise-density time series. The analysis demonstrated the capability of successfully detecting such attacks by observing the cross-correlation among Global Navigation Satellite System (GNSS) measurements time series. Cross-correlation quantified by Pearson’s correlation coefficients shows a relevant increment during harmful spoofing attacks. Under these conditions, the proposed methodology allows to rise a spoofing alarm in about 5 seconds with a false alarm probability of 1.5%. Furthermore, the proposed technique does not require low-level signal access, making it suitable for implementation at the application layer in a large number of smart devices with limited knowledge of their low-level system architecture. A validation campaign has been performed by testing 18 different Android™ devices and chipsets, thus demonstrating the applicability of the proposed method independently from the device under test.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"80 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":"135483541","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}
J-L. Demonfort, T. Authié, S. Trilles, P. Giorgis, R. Lembachar, G. Greze, F. Dufour, C. Boulanger, J. Lapie, G. Ceubah, L.S. Lawal
Four remarkable events are currently concurring to make possible the establishment of a very first demonstration of a preliminary DFMC SBAS service in Africa: • Galileo and GPS constellations near completion and/or replenishment ensure the provision of a significant number of operational dual frequencies (L1 & L5) navigation satellites; • The collaborative work of the Eurocae-RTCA WG-62 is well underway and DFMC MOPS are close to their finalization, while DFMC SARPs are endorsed and will be applicable by November 2023; • TAS (Thales Alenia Space) has developed an efficient DFMC navigation kernel compliant to the latest versions of those DFMC SBAS related standards; • And last but not the least, ASECNA (Agency for Air Navigation Safety in Africa and Madagascar) has officially launched its Augmented Navigation for Africa (ANGA) initiative, recognised by the International Civil Aviation Organisation, that intends to provide a full Legacy SBAS SoL service in the coming years but that is already broadcasting a demonstration service over African sub-saharian regions. More specifically, the Galileo constellation comprises 24 operational E1-E5a capable satellites since the last satellites launched in December 2021 are operational. The modernization of GPS space and ground segment is also in progress, and with the newest block III satellite operational since February 2023, the GPS constellation now comprises 18 operational L1-L5 capable satellites. GPS and Galileo have not reached the full operational capability for L1-L5/E1-E5a services, still they now offer a wide range of DFMC observability and measurements anywhere on the ground. The joint work of EUROCAE and RTCA is expected to give birth to a MOPS DFMC L5 Revision A (ED259A) in mid-2023. However, many successive work/draft versions have been produced up to now and we have based the results of this study on the latest available versions. Based on its long experience on various SBAS such as EGNOS or ANGA, TAS has developed a DFMC SBAS navigation kernel compliant with the work of the WG-62. As its Legacy SBAS L1 counterpart, this DFMC navigation kernel can be used to feed various SBAS performance studies with relevant and valuable augmentation messages. Moreover, it can also run in real time with actual GNSS stations measurements to provide an initial non safety-of-life SBAS service, very similarly to an operational SBAS system. The first part of the paper will deal with simulation studies in Africa. Under a CNES (Centre National d’Etudes Spatiales) contract, TAS has evaluated the performances of its DFMC navigation kernel using real GNSS data over a few representative African scenarios. The scenarios cover nominal and also degraded conditions (such as the loss of monitoring stations, or a depleted constellation). Two of those DFMC SBAS scenarios will be presented in the paper. They both augment GPS and Galileo constellations, they use the same network of 15 reference stations, but they differ on the t
目前，有四个值得注意的事件同时发生，使在非洲建立初步DFMC SBAS服务的首次演示成为可能:•伽利略和GPS星座接近完工和/或补充，确保提供大量可操作的双频(L1和L5)导航卫星;•Eurocae-RTCA WG-62的合作工作正在顺利进行，DFMC MOPS即将完成，而DFMC sarp已获得批准，将于2023年11月适用;TAS (Thales Alenia Space)开发了一种高效的DFMC导航内核，符合DFMC SBAS相关标准的最新版本;•最后但并非最不重要的是，ASECNA(非洲和马达加斯加空中航行安全局)已经正式启动了非洲增强导航(ANGA)计划，该计划得到了国际民航组织的认可，打算在未来几年内提供完整的传统SBAS SoL服务，但已经在非洲撒哈拉以南地区播放了示范服务。更具体地说，自2021年12月发射的最后一颗卫星开始运行以来，伽利略星座由24颗具有E1-E5a能力的卫星组成。GPS空间和地面部分的现代化也在进行中，随着最新的block III卫星自2023年2月开始运行，GPS星座现在由18颗具有L1-L5能力的卫星组成。GPS和伽利略还没有达到L1-L5/E1-E5a服务的完全操作能力，但它们现在仍然可以在地面上的任何地方提供广泛的DFMC可观测性和测量。EUROCAE和RTCA的联合工作预计将在2023年中期产生MOPS DFMC L5修订版a (ED259A)。然而，到目前为止，已经编写了许多后续的工作/草案版本，我们的研究结果是根据现有的最新版本。基于其在各种SBAS(如EGNOS或ANGA)上的长期经验，TAS已经开发了符合WG-62工作的DFMC SBAS导航内核。作为它的Legacy SBAS L1对应版本，这个DFMC导航内核可用于为各种SBAS性能研究提供相关且有价值的增强消息。此外，它还可以与实际的GNSS站测量实时运行，以提供初始的非生命安全SBAS服务，非常类似于操作SBAS系统。该文件的第一部分将讨论非洲的模拟研究。根据CNES (Centre National d’etudes Spatiales)的合同，TAS已经在几个具有代表性的非洲场景中使用真实GNSS数据评估了其DFMC导航内核的性能。这些情景包括名义条件和退化条件(例如失去监测站或耗尽星座)。本文将介绍其中两种DFMC SBAS场景。它们都增加了GPS和伽利略星座，它们使用相同的15个参考站网络，但它们在时间周期(第一种方案为2021年12月，第二种方案为2022年3月)上有所不同，以评估电离层活动对DFMC SBAS性能的影响。选定的参考台站网络包括参加国际GNSS服务(IGS)的各个机构的台站和SAGAIE网络的台站(stations ASECNA pour l 'Etude de l ' ionosphere re equoriale)。这些台站主要位于非洲赤道地区，它们的观测资料是从IGS或CNES服务器收集的。初步分析表明，该系统具有良好的导航性能。伪橙完整性满足高边际。水平位置误差(95%)小于0.9m，垂直位置误差(95%)小于1.6m，最大安全指数小于0.47。APVI和LPV200服务99%的可用区域主要覆盖非洲，从西经40°到东经80°，从南纬60°到北纬60°。此外，在整个非洲大陆，具有10米垂直警报限制的CAT-I可用性在90%以上的时间都是可用的。在本文的最后一部分，我们将描述根据2023年春季开始的演示而建立的实时DFMC SBAS测试台。该测试平台将使用ASECNA演示基础设施广播的ANGA信号来产生有价值的演示L1和L5增强消息。空间信号(SiS)将由Nigcomsat 1-R GEO卫星广播。据我们所知，这将是通过NIGCOMSAT-1R SBAS GEO在非洲播出的第一个DFMC SBAS演示SIS，也是世界上第一个。最后，本文将介绍ANGA DFMC演示信号在服务区域的定位精度、可用性、连续性和完整性裕度方面的性能分析。
{"title":"DFMC SBAS Prototype in Africa","authors":"J-L. Demonfort, T. Authié, S. Trilles, P. Giorgis, R. Lembachar, G. Greze, F. Dufour, C. Boulanger, J. Lapie, G. Ceubah, L.S. Lawal","doi":"10.33012/2023.19179","DOIUrl":"https://doi.org/10.33012/2023.19179","url":null,"abstract":"Four remarkable events are currently concurring to make possible the establishment of a very first demonstration of a preliminary DFMC SBAS service in Africa: • Galileo and GPS constellations near completion and/or replenishment ensure the provision of a significant number of operational dual frequencies (L1 & L5) navigation satellites; • The collaborative work of the Eurocae-RTCA WG-62 is well underway and DFMC MOPS are close to their finalization, while DFMC SARPs are endorsed and will be applicable by November 2023; • TAS (Thales Alenia Space) has developed an efficient DFMC navigation kernel compliant to the latest versions of those DFMC SBAS related standards; • And last but not the least, ASECNA (Agency for Air Navigation Safety in Africa and Madagascar) has officially launched its Augmented Navigation for Africa (ANGA) initiative, recognised by the International Civil Aviation Organisation, that intends to provide a full Legacy SBAS SoL service in the coming years but that is already broadcasting a demonstration service over African sub-saharian regions. More specifically, the Galileo constellation comprises 24 operational E1-E5a capable satellites since the last satellites launched in December 2021 are operational. The modernization of GPS space and ground segment is also in progress, and with the newest block III satellite operational since February 2023, the GPS constellation now comprises 18 operational L1-L5 capable satellites. GPS and Galileo have not reached the full operational capability for L1-L5/E1-E5a services, still they now offer a wide range of DFMC observability and measurements anywhere on the ground. The joint work of EUROCAE and RTCA is expected to give birth to a MOPS DFMC L5 Revision A (ED259A) in mid-2023. However, many successive work/draft versions have been produced up to now and we have based the results of this study on the latest available versions. Based on its long experience on various SBAS such as EGNOS or ANGA, TAS has developed a DFMC SBAS navigation kernel compliant with the work of the WG-62. As its Legacy SBAS L1 counterpart, this DFMC navigation kernel can be used to feed various SBAS performance studies with relevant and valuable augmentation messages. Moreover, it can also run in real time with actual GNSS stations measurements to provide an initial non safety-of-life SBAS service, very similarly to an operational SBAS system. The first part of the paper will deal with simulation studies in Africa. Under a CNES (Centre National d’Etudes Spatiales) contract, TAS has evaluated the performances of its DFMC navigation kernel using real GNSS data over a few representative African scenarios. The scenarios cover nominal and also degraded conditions (such as the loss of monitoring stations, or a depleted constellation). Two of those DFMC SBAS scenarios will be presented in the paper. They both augment GPS and Galileo constellations, they use the same network of 15 reference stations, but they differ on the t","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"1 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":"135483546","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}
Andrea Nardin, Alex Minetto, Salvatore Guzzi, Fabio Dovis, Lauren Konitzer, Joel J. K. Parker
The latest space missions have unveiled GNSS usability for distances greater than 187 000 km from the Earth’s surface. The actual availability and usability of GNSS signals beyond such an altitude are still questionable, and experimental evidence still lacks. The Lunar GNSS Receiver Experiment (LuGRE) is a joint NASA-Italian Space Agency (ASI) payload aiming at demonstrating GNSS-based positioning, navigation, and timing through its trajectory towards the Moon. After the launch in 2024, the payload will receive multi-frequency Global Positioning System (GPS) and Galileo signals across the different mission phases, and will conduct onboard and ground-based scientific experiments. Besides positioning and raw GNSS observables, the LuGRE payload will deliver snapshots of GNSS digital signal samples. Such snapshots will be at the core of a set of science investigations, and require the development of a post-processing unit being operated within the LuGRE ground segment throughout the mission. In this paper, we present an analysis that aims at identifying a minimum snapshot duration suitable for a successful, post-processing tracking of the recorded signal along the Moon transfer orbit and on the Moon surface. The processing of realistic mission-related signals has been performed to tune the receiver architecture and investigate the tracking performance in the LuGRE framework. Subsequently, a statistical analysis of the tracking lock conditions has been carried out leveraging a Monte Carlo approach to characterize the performance for different settings of the receiver front-end.
{"title":"Snapshot Tracking of GNSS Signals in Space: A Case Study at Lunar Distances","authors":"Andrea Nardin, Alex Minetto, Salvatore Guzzi, Fabio Dovis, Lauren Konitzer, Joel J. K. Parker","doi":"10.33012/2023.19174","DOIUrl":"https://doi.org/10.33012/2023.19174","url":null,"abstract":"The latest space missions have unveiled GNSS usability for distances greater than 187 000 km from the Earth’s surface. The actual availability and usability of GNSS signals beyond such an altitude are still questionable, and experimental evidence still lacks. The Lunar GNSS Receiver Experiment (LuGRE) is a joint NASA-Italian Space Agency (ASI) payload aiming at demonstrating GNSS-based positioning, navigation, and timing through its trajectory towards the Moon. After the launch in 2024, the payload will receive multi-frequency Global Positioning System (GPS) and Galileo signals across the different mission phases, and will conduct onboard and ground-based scientific experiments. Besides positioning and raw GNSS observables, the LuGRE payload will deliver snapshots of GNSS digital signal samples. Such snapshots will be at the core of a set of science investigations, and require the development of a post-processing unit being operated within the LuGRE ground segment throughout the mission. In this paper, we present an analysis that aims at identifying a minimum snapshot duration suitable for a successful, post-processing tracking of the recorded signal along the Moon transfer orbit and on the Moon surface. The processing of realistic mission-related signals has been performed to tune the receiver architecture and investigate the tracking performance in the LuGRE framework. Subsequently, a statistical analysis of the tracking lock conditions has been carried out leveraging a Monte Carlo approach to characterize the performance for different settings of the receiver front-end.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"80 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":"135483673","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}
In today's smartphone-driven era, our lives revolve around smartphones, resulting in high smartphone densities in various contexts. Furthermore, modern smartphones can exchange inter-user measurements via different sources, such as WiFi and BLE. In turn, the concept of online multi-user collaboration has recently emerged as a promising solution to improve the performance of standalone user-based indoor positioning systems (SU-IPSs). On this basis, this research proposes a real-time multi-user collaborative indoor positioning (RT-MUCIP) scheme. This scheme aims at boosting the indoor positioning performance of users with unavailable position information or low position confidence. The procedures of the proposed scheme can be summarized as follows: First, it checks the density and position confidence of the surrounding users. Users with high position confidence are identified. Subsequently, the proposed scheme adapts to the changing density of users in the following manner: In scenarios with sparse users, a nearby user with high confidence is explored and exploited to boost a near-neighbor with low position confidence. In areas with dense users, the weight of surrounding users’ positions and inter-user measurements are determined, and the RT-MUCIP solution is estimated using a weighted non-linear least squares algorithm. Additionally, inspired by wireless sensor networks, RT-MUCIP scheme proposed method to upgrade users observed in static mode with high positioning confidence to act as temporary anchor points. As a result of this upgrade, anchor node density increases, and overall positioning performance can be improved. To evaluate the performance of the proposed scheme, several tests were conducted in three scenarios. In light of the tests results, we can conclude that the proposed collaborative localization scheme can improve the localization accuracy of collaborated users without the need to use external resources.
{"title":"The Power of Many: Multi-User Collaborative Indoor Localization for Boosting Standalone User-Based Systems in Different Scenarios","authors":"Ahmed Mansour, Wu Chen, Huan Luo, Duojie Weng","doi":"10.33012/2023.19439","DOIUrl":"https://doi.org/10.33012/2023.19439","url":null,"abstract":"In today's smartphone-driven era, our lives revolve around smartphones, resulting in high smartphone densities in various contexts. Furthermore, modern smartphones can exchange inter-user measurements via different sources, such as WiFi and BLE. In turn, the concept of online multi-user collaboration has recently emerged as a promising solution to improve the performance of standalone user-based indoor positioning systems (SU-IPSs). On this basis, this research proposes a real-time multi-user collaborative indoor positioning (RT-MUCIP) scheme. This scheme aims at boosting the indoor positioning performance of users with unavailable position information or low position confidence. The procedures of the proposed scheme can be summarized as follows: First, it checks the density and position confidence of the surrounding users. Users with high position confidence are identified. Subsequently, the proposed scheme adapts to the changing density of users in the following manner: In scenarios with sparse users, a nearby user with high confidence is explored and exploited to boost a near-neighbor with low position confidence. In areas with dense users, the weight of surrounding users’ positions and inter-user measurements are determined, and the RT-MUCIP solution is estimated using a weighted non-linear least squares algorithm. Additionally, inspired by wireless sensor networks, RT-MUCIP scheme proposed method to upgrade users observed in static mode with high positioning confidence to act as temporary anchor points. As a result of this upgrade, anchor node density increases, and overall positioning performance can be improved. To evaluate the performance of the proposed scheme, several tests were conducted in three scenarios. In light of the tests results, we can conclude that the proposed collaborative localization scheme can improve the localization accuracy of collaborated users without the need to use external resources.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"2012 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":"135483685","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}
The Ground-Based Augmentation System (GBAS) is designed to augment the Global Positioning System (GPS) to provide precision approach and landing capabilities with essential accuracy and integrity. The variation of ionospheric delay between GBAS ground facility and the aircraft leads to residual error and need to be bounded. In order to do this, the GBAS ground facility broadcasts a parameter known as sigmavig to the aircraft, which represents the standard deviation of vertical ionospheric gradients that bounds the spatial gradients under nominal conditions. The sigmavig parameter is used to compute vertical protection levels for evaluating navigation integrity. As sigmavig varies with different region, the sigmavig for Hong Kong needs to be estimated to support GBAS implementation in this region. In this study, sigmavig for the year 2014 is estimated based on GNSS data obtained from Hong Kong Satellite Positioning Reference Station Network (SatRef). The results of sigmavig vary seasonally, with the maximum and minimum values occurring in spring and summer, respectively. To reflect this seasonality, quadratic polynomial expressions as functions of the day of the year were derived to upper-bound all sigmavig values.
{"title":"Seasonality of Nominal Ionospheric Gradient Using Time-Step Method Based on GNSS CORS Observations in Hong Kong","authors":"Wang Li, Yiping Jiang","doi":"10.33012/2023.19223","DOIUrl":"https://doi.org/10.33012/2023.19223","url":null,"abstract":"The Ground-Based Augmentation System (GBAS) is designed to augment the Global Positioning System (GPS) to provide precision approach and landing capabilities with essential accuracy and integrity. The variation of ionospheric delay between GBAS ground facility and the aircraft leads to residual error and need to be bounded. In order to do this, the GBAS ground facility broadcasts a parameter known as sigmavig to the aircraft, which represents the standard deviation of vertical ionospheric gradients that bounds the spatial gradients under nominal conditions. The sigmavig parameter is used to compute vertical protection levels for evaluating navigation integrity. As sigmavig varies with different region, the sigmavig for Hong Kong needs to be estimated to support GBAS implementation in this region. In this study, sigmavig for the year 2014 is estimated based on GNSS data obtained from Hong Kong Satellite Positioning Reference Station Network (SatRef). The results of sigmavig vary seasonally, with the maximum and minimum values occurring in spring and summer, respectively. To reflect this seasonality, quadratic polynomial expressions as functions of the day of the year were derived to upper-bound all sigmavig values.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"36 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":"135483691","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}
The vertical synthetic aperture radar (VSAR) is proposed as a navigation sensor, and a companion navigation algorithm – Trusted Inertial Terrain-Aided Navigation (TITAN) – is introduced. The TITAN algorithm consumes vector range-Doppler measurements produced by a VSAR and correlates them against a local digital terrain elevation map with an extended Kalman filter, enabling accurate navigation without the need for GPS. The navigation accuracy of the VSAR/TITAN combination is quantified with post-processed flight data, and shown to be within 15 meters.
{"title":"Trusted Inertial Terrain-Aided Navigation (TITAN)","authors":"Tucker Haydon, Todd E. Humphreys","doi":"10.33012/2023.19409","DOIUrl":"https://doi.org/10.33012/2023.19409","url":null,"abstract":"The vertical synthetic aperture radar (VSAR) is proposed as a navigation sensor, and a companion navigation algorithm – Trusted Inertial Terrain-Aided Navigation (TITAN) – is introduced. The TITAN algorithm consumes vector range-Doppler measurements produced by a VSAR and correlates them against a local digital terrain elevation map with an extended Kalman filter, enabling accurate navigation without the need for GPS. The navigation accuracy of the VSAR/TITAN combination is quantified with post-processed flight data, and shown to be within 15 meters.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"4 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":"135483694","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}
Odile Maliet, Julie Antic, Sébastien Trilles, Marie Abbal, Hélène Delfour-Cormier, Mickael Dall’Orso, Nicolas Giron, Guillaume Buscaret, Frédéric Bauert, Carlos Lopez de Echazarreta
The present paper summarizes the work carried out under the European H2020 R&D study “EGNOS Next System Feasibility study” for which a dedicated activity addresses a new integrity concept focused on the SBAS’ products in the pseudorange domain and aimed at new potential SoL users beyond the civil aviation user compliant to RTCA/EUROCAE MOPS [1], [2]. In GNSS applications, integrity is defined as a measure of the level of trust a user can place in a position estimate [3]. Th e classical Satellite Based Augmentation Systems (SBAS) aviation integrity concept relies on a stringent specification of the user algorithm implementation, described in the annex of the Minimum Operational Performance Standard (MOPS) [1], [2]. Similarly, again according to MOPS, current SBAS integrity data assumes that residual errors from broadcast corrections (satellite orbit/clock and ionosphere delays) are overbounded by a Gaussian Cumulative Distribution Function (CDF). For possible future SBAS’ applications such as maritime, rail, automotive and Unmanned Aerial Vehicle (UAV), the ability to provide tight and reliable protection volumes will be a critical enabler. To meet this level of performance, users will need to use more accurate positioning algorithms than the one specified in the MOPS for aviation users. This improved positioning service should address both the SBAS ability to broadcast highly accurate corrections and reliable integrity data, as well as the user algorithm formulation which uses these SBAS products. Moreover, these users may evolve in environments not favorable to the correct reception of GNSS signals, implying possibly a fusion with measurements coming from other sensors. In this context, the use of Kalman filtering and hybridization with non-GNSS sensors seem highly recommended. For users implementing Kalman filtering, the knowledge of the time correlation of the GNSS measurements errors is of importance to determine correct overbounding models. The current MOPS integrity concept is not adapted for such new user solutions. Typically, CDF overbounding is applicable only for GNSS measurements with residual errors not correlated with time. To cope with time correlation, recent developments introduce overbounding models of the Power Spectral Density (PSD) of the GNSS measurements residual errors[7]. In this paper we describe a new potential SBAS service which provides integrity parameters for a wide class of user algorithms. The new concept focuses on the integrity of SBAS products at pseudorange level to stay as much user agnostic as it can be, in the sense that it is demonstrated that these products are compatible with several user design solutions (variety of GNSS pre-correlation filters, variety of positioning algorithm formulations, several environments and user characteristics, etc…) and target integrity risks. For instance, these products are compatible with a Kalman filter using only code measurements and either the ionosphere -free combinati
{"title":"Integrity for Future SBAS Users: Concept and Experimentations","authors":"Odile Maliet, Julie Antic, Sébastien Trilles, Marie Abbal, Hélène Delfour-Cormier, Mickael Dall’Orso, Nicolas Giron, Guillaume Buscaret, Frédéric Bauert, Carlos Lopez de Echazarreta","doi":"10.33012/2023.19191","DOIUrl":"https://doi.org/10.33012/2023.19191","url":null,"abstract":"The present paper summarizes the work carried out under the European H2020 R&D study “EGNOS Next System Feasibility study” for which a dedicated activity addresses a new integrity concept focused on the SBAS’ products in the pseudorange domain and aimed at new potential SoL users beyond the civil aviation user compliant to RTCA/EUROCAE MOPS [1], [2]. In GNSS applications, integrity is defined as a measure of the level of trust a user can place in a position estimate [3]. Th e classical Satellite Based Augmentation Systems (SBAS) aviation integrity concept relies on a stringent specification of the user algorithm implementation, described in the annex of the Minimum Operational Performance Standard (MOPS) [1], [2]. Similarly, again according to MOPS, current SBAS integrity data assumes that residual errors from broadcast corrections (satellite orbit/clock and ionosphere delays) are overbounded by a Gaussian Cumulative Distribution Function (CDF). For possible future SBAS’ applications such as maritime, rail, automotive and Unmanned Aerial Vehicle (UAV), the ability to provide tight and reliable protection volumes will be a critical enabler. To meet this level of performance, users will need to use more accurate positioning algorithms than the one specified in the MOPS for aviation users. This improved positioning service should address both the SBAS ability to broadcast highly accurate corrections and reliable integrity data, as well as the user algorithm formulation which uses these SBAS products. Moreover, these users may evolve in environments not favorable to the correct reception of GNSS signals, implying possibly a fusion with measurements coming from other sensors. In this context, the use of Kalman filtering and hybridization with non-GNSS sensors seem highly recommended. For users implementing Kalman filtering, the knowledge of the time correlation of the GNSS measurements errors is of importance to determine correct overbounding models. The current MOPS integrity concept is not adapted for such new user solutions. Typically, CDF overbounding is applicable only for GNSS measurements with residual errors not correlated with time. To cope with time correlation, recent developments introduce overbounding models of the Power Spectral Density (PSD) of the GNSS measurements residual errors[7]. In this paper we describe a new potential SBAS service which provides integrity parameters for a wide class of user algorithms. The new concept focuses on the integrity of SBAS products at pseudorange level to stay as much user agnostic as it can be, in the sense that it is demonstrated that these products are compatible with several user design solutions (variety of GNSS pre-correlation filters, variety of positioning algorithm formulations, several environments and user characteristics, etc…) and target integrity risks. For instance, these products are compatible with a Kalman filter using only code measurements and either the ionosphere -free combinati","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"107 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":"135483696","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}
The Korean satellite based augmentation system (SBAS) named the Korea augmentation satellite system (KASS) program has been initiated in October 2014. The program work is currently in the system qualification phase. The KASS complies with the SBAS requirements from the International Civil Aviation Organization (ICAO) published in Annex 10. The KASS signal-in-space also complies with the corresponding requirements in the SBAS minimum operational performance standards (MOPS) published by Radio Technical Commission for Aeronautics (RTCA). The KASS system has four ground subsystems and two GEO satellites. The configuration of the KASS ground subsystems comprises of seven KASS reference stations (KRS), two KASS processing stations (KPS), two KASS control stations (KCS) and three KASS uplink stations (KUS). The KRS collects measurement data and broadcast messages from all GPS and geostationary earth orbit (GEO) satellites in view and delivers the data and messages to the KPS. The KPS performs correction processing, safety processing, and SBAS message processing. The KUS generates “GPS-like” signals combined with the SBAS messages from the KPS and transmits them to the GEO satellites. The GEO satellites receive signals from the KUS and transmit GPS compatible signals. The KCS controls and monitors all the KASS subsystems. The KASS system comprises the network segment ensuring all subsystems distributed across Korea wide area network (WAN) and the WAN network monitoring (WNM). The virtual private network (VPN) for WAN were installed in each subsystem sites and one of key parameters for the WAN qualification was verified with data stream generated by tool. This connectivity validation which is to ensure the reliability of the dedicated line and network equipment by measuring the number of delays and losses of packets transmitted from the KASS WAN, which enables the detection of coarse unstable line installations. This paper covers the overall KASS WAN architecture on the installed sites, measurement methods and, the connectivity validation results. The connectivity validation measures delay and loss of the dedicated line and equipment connected between the subsystems at each site. Although the measurements have been observed during the test period, the connectivity validation results satisfied the confidence level to be assigned by system requirements.
{"title":"Wide Area Network (WAN) Connectivity Validation on Installed Sites of Korea Augmentation Satellite System (KASS)","authors":"Chulhee Choi, Eunsung Lee, Daehee Won","doi":"10.33012/2023.19176","DOIUrl":"https://doi.org/10.33012/2023.19176","url":null,"abstract":"The Korean satellite based augmentation system (SBAS) named the Korea augmentation satellite system (KASS) program has been initiated in October 2014. The program work is currently in the system qualification phase. The KASS complies with the SBAS requirements from the International Civil Aviation Organization (ICAO) published in Annex 10. The KASS signal-in-space also complies with the corresponding requirements in the SBAS minimum operational performance standards (MOPS) published by Radio Technical Commission for Aeronautics (RTCA). The KASS system has four ground subsystems and two GEO satellites. The configuration of the KASS ground subsystems comprises of seven KASS reference stations (KRS), two KASS processing stations (KPS), two KASS control stations (KCS) and three KASS uplink stations (KUS). The KRS collects measurement data and broadcast messages from all GPS and geostationary earth orbit (GEO) satellites in view and delivers the data and messages to the KPS. The KPS performs correction processing, safety processing, and SBAS message processing. The KUS generates “GPS-like” signals combined with the SBAS messages from the KPS and transmits them to the GEO satellites. The GEO satellites receive signals from the KUS and transmit GPS compatible signals. The KCS controls and monitors all the KASS subsystems. The KASS system comprises the network segment ensuring all subsystems distributed across Korea wide area network (WAN) and the WAN network monitoring (WNM). The virtual private network (VPN) for WAN were installed in each subsystem sites and one of key parameters for the WAN qualification was verified with data stream generated by tool. This connectivity validation which is to ensure the reliability of the dedicated line and network equipment by measuring the number of delays and losses of packets transmitted from the KASS WAN, which enables the detection of coarse unstable line installations. This paper covers the overall KASS WAN architecture on the installed sites, measurement methods and, the connectivity validation results. The connectivity validation measures delay and loss of the dedicated line and equipment connected between the subsystems at each site. Although the measurements have been observed during the test period, the connectivity validation results satisfied the confidence level to be assigned by system requirements.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"80 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":"135483700","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}
Jean-Rémi De Boer, Nicolas Bourry, Cyril Sarramiac, Guillaume Comelli, ByungSeok Lee, Minhyuk Son, Eunsung Lee, Cheon Sig Sin
Thales Alenia Space is recognized as a world leader in satellite based navigation systems, in particular, as the prime contractor for EGNOS V2. Korea Aerospace Research Institute (KARI) for the government of the Republic of Korea, selected Thales Alenia Space as industry prime contractor for the development of KASS program. In this frame, Thales Alenia Space has designed a new and innovative solution for KASS Uplink Station (KUS). Following KUS deployments, first Signal-in-Space (SiS) transmission through MEASAT-3D on Pseudo Random Noise (PRN) 134 occurred in December 2022. The KUS is composed of two subsystems: the KUS Signal Generation Subsystem (KUS/SGS) developed by Thales Alenia Space to ensure the signal generation and the long loop and the KUS Radio Frequency Subsystem (KUS/RFS) developed by KT&KTSAT that ensures the signal amplification and the interface with the satellite. The heart of the SBAS signal generation is ensured by two functions of the KUS/SGS : the first European Signal Generator used in SBAS uplink station implementing GEO L1 and L5 signal generation according to [1], [2], and [3] and the long loop algorithm which is a dedicated software thread aiming to compute delays and frequency shifts to synchronize to Global Positioning System (GPS) time L1 and L5 messages emission at the phase center of the GEO satellite broadcasting antenna. This paper presents the overall KASS system design related to uplink stations implementation, the design and main features of the KUS/SGS and an overview of the performances obtained during both KUS/SGS factory qualification and on site acceptation including the KUS/RFS and the KASS first geostationary satellite (MEASAT-3D) demonstrating the main performances achievement. Through its flexibility and its high level of performance, the KUS/SGS design is a perfect candidate to address any needs of SBAS uplink station for other SBAS programs.
{"title":"First Signal-in-Space for KOREA Augmentation Satellite System (KASS)","authors":"Jean-Rémi De Boer, Nicolas Bourry, Cyril Sarramiac, Guillaume Comelli, ByungSeok Lee, Minhyuk Son, Eunsung Lee, Cheon Sig Sin","doi":"10.33012/2023.19228","DOIUrl":"https://doi.org/10.33012/2023.19228","url":null,"abstract":"Thales Alenia Space is recognized as a world leader in satellite based navigation systems, in particular, as the prime contractor for EGNOS V2. Korea Aerospace Research Institute (KARI) for the government of the Republic of Korea, selected Thales Alenia Space as industry prime contractor for the development of KASS program. In this frame, Thales Alenia Space has designed a new and innovative solution for KASS Uplink Station (KUS). Following KUS deployments, first Signal-in-Space (SiS) transmission through MEASAT-3D on Pseudo Random Noise (PRN) 134 occurred in December 2022. The KUS is composed of two subsystems: the KUS Signal Generation Subsystem (KUS/SGS) developed by Thales Alenia Space to ensure the signal generation and the long loop and the KUS Radio Frequency Subsystem (KUS/RFS) developed by KT&KTSAT that ensures the signal amplification and the interface with the satellite. The heart of the SBAS signal generation is ensured by two functions of the KUS/SGS : the first European Signal Generator used in SBAS uplink station implementing GEO L1 and L5 signal generation according to [1], [2], and [3] and the long loop algorithm which is a dedicated software thread aiming to compute delays and frequency shifts to synchronize to Global Positioning System (GPS) time L1 and L5 messages emission at the phase center of the GEO satellite broadcasting antenna. This paper presents the overall KASS system design related to uplink stations implementation, the design and main features of the KUS/SGS and an overview of the performances obtained during both KUS/SGS factory qualification and on site acceptation including the KUS/RFS and the KASS first geostationary satellite (MEASAT-3D) demonstrating the main performances achievement. Through its flexibility and its high level of performance, the KUS/SGS design is a perfect candidate to address any needs of SBAS uplink station for other SBAS programs.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"57 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":"135483704","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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