Localization under GNSS-denied environments has become a significant research focus in recent years. Traditional solutions for accurate positioning often rely on expensive multi-sensor fusion technologies, such as vision, inertial measurement unit (IMU), and lidar, which are primarily used in autonomous vehicles. However, these solutions can be costly and not suitable for all applications. A new paradigm for positioning services is the use of roadside sensing systems (RSS). These systems utilize vision, radar, and/or lidar sensors to detect road users and transmit the information through cellular vehicle-to-everything (C-V2X) technology. Unlike sensor-fusion-based ego-state estimation used in autonomous vehicles, RSS offloads the computation and sensing work to the roadside, providing positioning services to all connected vehicles (CV) at a lower cost. In this work, we focus on the accuracy analysis of a roadside sensing system for localization. We first proposed a spatiotemporal decoupling association method is then used to associate the RSS positioning data with the ground truth, mitigating timing errors. Then the accuracy analysis and model fitting are performed using data collected from multiple RSS deployed in different locations in China. Finally, we establish three different noise models for the general RSS system by performing a 2-D histogram regression on localization errors, and recommend a simple linear model for general RSS. The outcome of this study provides a practical spatial-related confidence model for RSS localization service users, forming a solid foundation for future applications, particularly for the fusion of GNSS and RSS in autonomous and connected vehicle systems.
{"title":"Localization Accuracy Analysis for Roadside Sensing System","authors":"Zheng Gong, Zhen Liao, Xuyan Bao, Bingyan Yu, Yuming Ge","doi":"10.33012/2023.19226","DOIUrl":"https://doi.org/10.33012/2023.19226","url":null,"abstract":"Localization under GNSS-denied environments has become a significant research focus in recent years. Traditional solutions for accurate positioning often rely on expensive multi-sensor fusion technologies, such as vision, inertial measurement unit (IMU), and lidar, which are primarily used in autonomous vehicles. However, these solutions can be costly and not suitable for all applications. A new paradigm for positioning services is the use of roadside sensing systems (RSS). These systems utilize vision, radar, and/or lidar sensors to detect road users and transmit the information through cellular vehicle-to-everything (C-V2X) technology. Unlike sensor-fusion-based ego-state estimation used in autonomous vehicles, RSS offloads the computation and sensing work to the roadside, providing positioning services to all connected vehicles (CV) at a lower cost. In this work, we focus on the accuracy analysis of a roadside sensing system for localization. We first proposed a spatiotemporal decoupling association method is then used to associate the RSS positioning data with the ground truth, mitigating timing errors. Then the accuracy analysis and model fitting are performed using data collected from multiple RSS deployed in different locations in China. Finally, we establish three different noise models for the general RSS system by performing a 2-D histogram regression on localization errors, and recommend a simple linear model for general RSS. The outcome of this study provides a practical spatial-related confidence model for RSS localization service users, forming a solid foundation for future applications, particularly for the fusion of GNSS and RSS in autonomous and connected vehicle systems.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"22 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":"135482207","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}
A Ground-Based Augmentation System (GBAS) is a flight critical system that supports for safe, efficient, and essentially all-weather aircraft precision approach and landing operations. GBAS Approach Service Type (GAST)-X a proposed architecture candidate for future dual frequency multi-constellation (DFMC) GBAS, consisting of an uplink to the airborne that includes dual frequency raw measurements. The nominal mode of operation uses divergence-free (DFree) smoothing with up to 600 seconds of carrier smoothing, while ionosphere-free (IFree) and conventional single frequency (SF) smoothing are performed in parallel to support degraded/backup modes of operation. The use of DFree smoothed measurements makes the system less susceptible to ionospheric gradient threats. One of the benefits of GAST-X is the higher operational availability in equatorial areas due to the higher number of satellites in view offered by the multi-constellation services. In this study, the performance of different DFMC GBAS architectures was assessed using data from a set of five receivers located in Brazil, using GPS and Galileo data. The results showed that the protection levels calculated using the GAST-X architecture were better than those calculated using GAST F, which is an alternative architecture that uses SF 100-second smoothing as its primary mode of operation and with the second frequency being used for ionospheric gradient monitoring, demonstrating the robustness of the service, especially when using DFree smoothed pseudoranges. However, DFMC GBAS performance can degrade during conditions where cycle slips occur, and depending on the intensity of ionospheric scintillation, one or more backup modes can be more suitable than the nominal DFree mode of GAST-X or the single-frequency mode of GAST F.
{"title":"Assessing the Performance of Dual-Frequency Multi-Constellation GBAS Architectures during Periods of Ionospheric Scintillation in Brazil","authors":"Crislaine Menezes da Silva, Weverton da Costa Silva, Felipe Tintino Linhares de Souza, João Francisco Galera Monico, Daniele Barroca Marra Alves, Italo Tsuchiya, Glaucia Balvedi, Tim Murphy, Susumu Saito, Joel Wichgers","doi":"10.33012/2023.19303","DOIUrl":"https://doi.org/10.33012/2023.19303","url":null,"abstract":"A Ground-Based Augmentation System (GBAS) is a flight critical system that supports for safe, efficient, and essentially all-weather aircraft precision approach and landing operations. GBAS Approach Service Type (GAST)-X a proposed architecture candidate for future dual frequency multi-constellation (DFMC) GBAS, consisting of an uplink to the airborne that includes dual frequency raw measurements. The nominal mode of operation uses divergence-free (DFree) smoothing with up to 600 seconds of carrier smoothing, while ionosphere-free (IFree) and conventional single frequency (SF) smoothing are performed in parallel to support degraded/backup modes of operation. The use of DFree smoothed measurements makes the system less susceptible to ionospheric gradient threats. One of the benefits of GAST-X is the higher operational availability in equatorial areas due to the higher number of satellites in view offered by the multi-constellation services. In this study, the performance of different DFMC GBAS architectures was assessed using data from a set of five receivers located in Brazil, using GPS and Galileo data. The results showed that the protection levels calculated using the GAST-X architecture were better than those calculated using GAST F, which is an alternative architecture that uses SF 100-second smoothing as its primary mode of operation and with the second frequency being used for ionospheric gradient monitoring, demonstrating the robustness of the service, especially when using DFree smoothed pseudoranges. However, DFMC GBAS performance can degrade during conditions where cycle slips occur, and depending on the intensity of ionospheric scintillation, one or more backup modes can be more suitable than the nominal DFree mode of GAST-X or the single-frequency mode of GAST F.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"62 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":"135482358","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}
While the Automatic Dependent Surveillance-Broadcast (ADS-B) has been widely used for air traffic operations and management, it has also been useful recently in identifying, detecting, and localizing (IDL) potential GNSS/RFI jamming sources in regional, high air traffic environments. With an increase in reported GNSS interference around the world, there is a necessity to find and remove jammers from the environment to prevent additional unsafe air travel operations. The major indicator that infers as whether an aircraft is likely being jammed (from ADS-B) is by monitoring the Navigational Integrity Category (NIC) value included in the ADS-B message. While not as effective as other metrics typically used in interference detection, it can still provide an indication if jamming is present, but presents an opportunity in localizing the potential source in real time. This paper seeks to approximate the area of potential GNSS/RFI interference by fitting a Euclidean Cone to ADS-B data reporting low NIC values. This problem is formulated as a convex optimization problem, which is derived from an alternative version of maximum inscribed ellipsoid approach. By fitting the optimal cone to data potentially impacted by interference, the apex of the cone will reveal the estimated jamming location. Raw ADS-B data is processed, decoded, interpolated and filtered to improve localization results. The proposed convex formulation is then applied to two reported interference events, the first over a period of 36 hours near Denver International Airport in January 2022, and the second over roughly 8 hours near the Dallas-Fort Worth Area in October 2022. The Denver localization results show that the four estimated jamming locations - calculated from four six-hour time windows - are grouped in between the downtown Denver area and the airport. With the Dallas interference jamming localization results, it can be seen that the three estimated jamming locations - determined from three, one hour windows - also show a tighter grouping on the southern side of the Dallas/Fort Worth area.
{"title":"Approximating Regional GNSS Interference Sources as a Convex Optimization Problem Using ADS-B Data","authors":"Michael Dacus, Zixi Liu, Sherman Lo, Todd Walter","doi":"10.33012/2023.19414","DOIUrl":"https://doi.org/10.33012/2023.19414","url":null,"abstract":"While the Automatic Dependent Surveillance-Broadcast (ADS-B) has been widely used for air traffic operations and management, it has also been useful recently in identifying, detecting, and localizing (IDL) potential GNSS/RFI jamming sources in regional, high air traffic environments. With an increase in reported GNSS interference around the world, there is a necessity to find and remove jammers from the environment to prevent additional unsafe air travel operations. The major indicator that infers as whether an aircraft is likely being jammed (from ADS-B) is by monitoring the Navigational Integrity Category (NIC) value included in the ADS-B message. While not as effective as other metrics typically used in interference detection, it can still provide an indication if jamming is present, but presents an opportunity in localizing the potential source in real time. This paper seeks to approximate the area of potential GNSS/RFI interference by fitting a Euclidean Cone to ADS-B data reporting low NIC values. This problem is formulated as a convex optimization problem, which is derived from an alternative version of maximum inscribed ellipsoid approach. By fitting the optimal cone to data potentially impacted by interference, the apex of the cone will reveal the estimated jamming location. Raw ADS-B data is processed, decoded, interpolated and filtered to improve localization results. The proposed convex formulation is then applied to two reported interference events, the first over a period of 36 hours near Denver International Airport in January 2022, and the second over roughly 8 hours near the Dallas-Fort Worth Area in October 2022. The Denver localization results show that the four estimated jamming locations - calculated from four six-hour time windows - are grouped in between the downtown Denver area and the airport. With the Dallas interference jamming localization results, it can be seen that the three estimated jamming locations - determined from three, one hour windows - also show a tighter grouping on the southern side of the Dallas/Fort Worth area.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"16 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":"135482359","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 research assesses the feasibility and conducts performance analysis of an LEO-aided GNSS-based navigation system under weak GNSS signal environments. The Doppler measurements are extracted from the Iridium NEXT and Orbcomm constellations to increase the LEO satellite signals availability. The simplex signals of Iridium Next are received to extract Doppler frequency. Since the simplex signal is a pure tone, the fast Fourier transform method is adopted to search for the received carrier frequency and obtain Doppler shift measurement. The Doppler shift of Orbcomm can be extracted the same way as Iridium NEXT. The Doppler extraction from Iridium NEXT and Orbcomm will be combined with global positioning system (GPS) Doppler acquisition and tracking procedure to conduct the experiments. After extracting the Doppler measurements from Iridium NEXT, Orbcomm, and GPS, the measurements will input an extended Kalman filter to generate navigation solutions. The experiments will compare the impact of including the LEO satellite signal in weak GNSS signal environments in which less than four GPS signals are available, then add the LEO satellite signals to manifest the effect of opportunistic navigation through space-based SOPs. Two environments will be the trial fields, including the deep urban canyons, the dense forest, and the indoor environments, which make discontinuous position solutions. Two main contributions of the paper are as follows. 1) Combination of Doppler and pseudorange measurements of GPS signals and Doppler measurements from two LEO constellations at receiver level and 2) verification and analysis of the performance of an LEO-aided GNSS under weak GNSS signal environments.
{"title":"Performance Analysis of LEO Multi-Constellation Aided GNSS Positioning Under Weak Signals Environments","authors":"Ya-Xun Yang, Shau-Shiun Jan","doi":"10.33012/2023.19329","DOIUrl":"https://doi.org/10.33012/2023.19329","url":null,"abstract":"This research assesses the feasibility and conducts performance analysis of an LEO-aided GNSS-based navigation system under weak GNSS signal environments. The Doppler measurements are extracted from the Iridium NEXT and Orbcomm constellations to increase the LEO satellite signals availability. The simplex signals of Iridium Next are received to extract Doppler frequency. Since the simplex signal is a pure tone, the fast Fourier transform method is adopted to search for the received carrier frequency and obtain Doppler shift measurement. The Doppler shift of Orbcomm can be extracted the same way as Iridium NEXT. The Doppler extraction from Iridium NEXT and Orbcomm will be combined with global positioning system (GPS) Doppler acquisition and tracking procedure to conduct the experiments. After extracting the Doppler measurements from Iridium NEXT, Orbcomm, and GPS, the measurements will input an extended Kalman filter to generate navigation solutions. The experiments will compare the impact of including the LEO satellite signal in weak GNSS signal environments in which less than four GPS signals are available, then add the LEO satellite signals to manifest the effect of opportunistic navigation through space-based SOPs. Two environments will be the trial fields, including the deep urban canyons, the dense forest, and the indoor environments, which make discontinuous position solutions. Two main contributions of the paper are as follows. 1) Combination of Doppler and pseudorange measurements of GPS signals and Doppler measurements from two LEO constellations at receiver level and 2) verification and analysis of the performance of an LEO-aided GNSS under weak GNSS signal environments.","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":"135482490","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 application of the impulse-radio ultra-wide band technology is already established in indoor localization. Usually, two-way ranging (TWR) or time-difference of arrival (TDoA) approaches are utilized. In this paper it is shown that it is possible to perform time of arrival (ToA) positioning with accuracy similar to the TDoA. The ToA method estimates the bias between the clocks of the anchors (fixed infrastructure nodes) and the tag (localized user equipment). As a direct consequence, any timestamps taken by the tag may be converted to the common system timescale with accuracy of several nanoseconds. The approach is verified by real measurements. We demonstrate that the positioning solution can be obtained by least-squares optimization on epoch-by-epoch basis. We also show that the extended Kalman filter can be used to estimate tag position along with the bias and drift of its clock.
{"title":"Pseudorange-Based IR-UWB Localization","authors":"Václav Navrátil, Josef Krska","doi":"10.33012/2023.19203","DOIUrl":"https://doi.org/10.33012/2023.19203","url":null,"abstract":"The application of the impulse-radio ultra-wide band technology is already established in indoor localization. Usually, two-way ranging (TWR) or time-difference of arrival (TDoA) approaches are utilized. In this paper it is shown that it is possible to perform time of arrival (ToA) positioning with accuracy similar to the TDoA. The ToA method estimates the bias between the clocks of the anchors (fixed infrastructure nodes) and the tag (localized user equipment). As a direct consequence, any timestamps taken by the tag may be converted to the common system timescale with accuracy of several nanoseconds. The approach is verified by real measurements. We demonstrate that the positioning solution can be obtained by least-squares optimization on epoch-by-epoch basis. We also show that the extended Kalman filter can be used to estimate tag position along with the bias and drift of its clock.","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":"135482502","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}
Methods have been developed and simulation-tested to perform swarm navigation using signals of opportunity from noncooperating Low-Earth-Orbit (LEO) satellites and cross-links between the swarm elements. This work seeks to exploit swarm capabilities in order to refine coarse initial estimates of the true orbits of the LEO satellites and thereby achieve accurate swarm navigation. The swarm consists of multiple quadrotor aircraft that can measure carrier Doppler shift from LEO satellites along with pseudorange between swarm members. Each swarm component carries an altimeter and a magnetometer too. A centralized Kalman filter estimates all swarm component states and all satellite states. Better characterization of Two-Line Element (TLE) uncertainties is important to such a system. Having better initial ephemerides for the satellites, as are available for Starlink satellites, is even more important. Achievable swarm position accuracy starting from TLEs is about 100 meters, but it improves to single-digit meters when using precise Starlink ephemerides. This work also presents a leapfrogging method in which successive members of a swarm of vehicles land and act as inertial reference stations. This not only significantly reduces the uncertainty bounds, but also allows the navigation algorithm to perform well even in the presence of strong wind, which is time-correlated (unbeknownst to the filter).
{"title":"Swarm Navigation Using Signals of Opportunity from Uncooperative LEO Satellites","authors":"Dawson Beatty, Mark L. Psiaki","doi":"10.33012/2023.19468","DOIUrl":"https://doi.org/10.33012/2023.19468","url":null,"abstract":"Methods have been developed and simulation-tested to perform swarm navigation using signals of opportunity from noncooperating Low-Earth-Orbit (LEO) satellites and cross-links between the swarm elements. This work seeks to exploit swarm capabilities in order to refine coarse initial estimates of the true orbits of the LEO satellites and thereby achieve accurate swarm navigation. The swarm consists of multiple quadrotor aircraft that can measure carrier Doppler shift from LEO satellites along with pseudorange between swarm members. Each swarm component carries an altimeter and a magnetometer too. A centralized Kalman filter estimates all swarm component states and all satellite states. Better characterization of Two-Line Element (TLE) uncertainties is important to such a system. Having better initial ephemerides for the satellites, as are available for Starlink satellites, is even more important. Achievable swarm position accuracy starting from TLEs is about 100 meters, but it improves to single-digit meters when using precise Starlink ephemerides. This work also presents a leapfrogging method in which successive members of a swarm of vehicles land and act as inertial reference stations. This not only significantly reduces the uncertainty bounds, but also allows the navigation algorithm to perform well even in the presence of strong wind, which is time-correlated (unbeknownst to the filter).","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"79 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":"135482771","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 volume of marine vessels using the Automatic Identification System (AIS) has been increasing since its inception in 2000. This increase is resulting in overloading of the two channels that carry the AIS transmissions. In response to this overloading of AIS, international organizations like the International Telecommunication Union (ITU), the International Maritime Organization (IMO), and the International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA) are developing the next generation AIS – called Very High Frequency (VHF) Data Exchange System (VDES). VDES is a technological concept utilizing terrestrial and satellite radio communication links in the VHF maritime mobile band to facilitate globally interoperable digital data exchange between ships, between ships and shore, between shore and ships, between ships and satellites, and between satellites and ships. It will increase the number of channels available for the exchange of safety and navigation information. The U.S. Coast Guard (USCG) Research & Development Center (RDC) is researching VDES to assess the suitability for implementation. To support VDES research, RDC developed a technology road map and performed two field tests. The first field test was conducted in the New London, CT area from June – September 2021 and focused on the transmission of Sensitive but Unclassified Tactical Information Exchange and Display System (STEDS) messages using VDES Application Specific Message (ASM) channels. STEDS is presently implemented by the USCG on AIS channels. The results of Field Test 1 indicated that there are no technical obstacles to transitioning USCG STEDS traffic from AIS to ASM channels. The performance of the ASM channels with Forward Error Correction (FEC) is equivalent to that of the AIS channels. The second field test was also conducted in the New London, CT area with data collection from August – December 2022. The focus of the second test was to assess the performance of the VHF Data Exchange (VDE) terrestrial higher bandwidth channels and determine if it could meet USCG communications needs, both for internal (USCG to USCG) and for external (USCG to maritime public) communications. The test included an evaluation of the state of the market and interoperability of equipment from multiple venders. The results of the testing show that while the VDE high bandwidth channel can be used for moving larger amounts of data (such as generic files or small pictures) the range is less than that of the AIS and ASM channels. Additional research needs to be done to determine if this reduction in range on the VDE channels is associated with implementing the standard in VDES equipment or is a function of the system design itself. This paper discusses the testing and results and addresses future work plans such as SAR pattern transmission and VDES ranging mode.
{"title":"VDE-Terrestrial Channel Performance Assessment","authors":"Gregory Johnson, Kenneth Dykstra, John Forster, James Spilsbury","doi":"10.33012/2023.19430","DOIUrl":"https://doi.org/10.33012/2023.19430","url":null,"abstract":"The volume of marine vessels using the Automatic Identification System (AIS) has been increasing since its inception in 2000. This increase is resulting in overloading of the two channels that carry the AIS transmissions. In response to this overloading of AIS, international organizations like the International Telecommunication Union (ITU), the International Maritime Organization (IMO), and the International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA) are developing the next generation AIS – called Very High Frequency (VHF) Data Exchange System (VDES). VDES is a technological concept utilizing terrestrial and satellite radio communication links in the VHF maritime mobile band to facilitate globally interoperable digital data exchange between ships, between ships and shore, between shore and ships, between ships and satellites, and between satellites and ships. It will increase the number of channels available for the exchange of safety and navigation information. The U.S. Coast Guard (USCG) Research & Development Center (RDC) is researching VDES to assess the suitability for implementation. To support VDES research, RDC developed a technology road map and performed two field tests. The first field test was conducted in the New London, CT area from June – September 2021 and focused on the transmission of Sensitive but Unclassified Tactical Information Exchange and Display System (STEDS) messages using VDES Application Specific Message (ASM) channels. STEDS is presently implemented by the USCG on AIS channels. The results of Field Test 1 indicated that there are no technical obstacles to transitioning USCG STEDS traffic from AIS to ASM channels. The performance of the ASM channels with Forward Error Correction (FEC) is equivalent to that of the AIS channels. The second field test was also conducted in the New London, CT area with data collection from August – December 2022. The focus of the second test was to assess the performance of the VHF Data Exchange (VDE) terrestrial higher bandwidth channels and determine if it could meet USCG communications needs, both for internal (USCG to USCG) and for external (USCG to maritime public) communications. The test included an evaluation of the state of the market and interoperability of equipment from multiple venders. The results of the testing show that while the VDE high bandwidth channel can be used for moving larger amounts of data (such as generic files or small pictures) the range is less than that of the AIS and ASM channels. Additional research needs to be done to determine if this reduction in range on the VDE channels is associated with implementing the standard in VDES equipment or is a function of the system design itself. This paper discusses the testing and results and addresses future work plans such as SAR pattern transmission and VDES ranging mode.","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":"135483151","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}
Unlike outdoor spaces, indoor spaces are not naturally interconnected. To provide efficient indoor location-based services, we structured indoor spaces into Sector, Building, Level, and Spot, and connected them through a relational database on the Cloud Platform. The relational database enables the seamless interconnection, easy management and modification of each space. Additionally, engine systems for indoor localization are established on the Cloud Platform to provide accurate spatial and positioning information. These engines are designed to be independent, allowing efficient resource utilization based on users' service demands. We conducted successful and seamless test at COEX, one of the largest underground parking lots in Seoul, South Korea, demonstrating a location error of 4.795m and a floor estimation accuracy of 97.926% for seamless floor transitions. The approach presented in this paper enables efficient management of indoor spaces and provides seamless location services tailored to users' needs.
{"title":"Indoor Mapping Structure Based on Cloud Platform for Seamless and Effective Indoor Localization","authors":"Taehun Kim, Beomju Shin, Chung G. Kang, Donghyun Shin, Changsoo Yu, Hankyeol Kyung, Taikjin Lee","doi":"10.33012/2023.19331","DOIUrl":"https://doi.org/10.33012/2023.19331","url":null,"abstract":"Unlike outdoor spaces, indoor spaces are not naturally interconnected. To provide efficient indoor location-based services, we structured indoor spaces into Sector, Building, Level, and Spot, and connected them through a relational database on the Cloud Platform. The relational database enables the seamless interconnection, easy management and modification of each space. Additionally, engine systems for indoor localization are established on the Cloud Platform to provide accurate spatial and positioning information. These engines are designed to be independent, allowing efficient resource utilization based on users' service demands. We conducted successful and seamless test at COEX, one of the largest underground parking lots in Seoul, South Korea, demonstrating a location error of 4.795m and a floor estimation accuracy of 97.926% for seamless floor transitions. The approach presented in this paper enables efficient management of indoor spaces and provides seamless location services tailored to users' needs.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"440 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":"135483166","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}
Given the increasing number of critical applications relying on GNSS, GNSS spectrum monitoring is becoming more and more crucial. Monitoring from low Earth orbit (LEO) has been investigated, and interference-source geolocalization has been demonstrated. In this paper, results are shown from the Bobcat-1 CubeSat mission which recorded multi-GNSS measurements but was not optimized for spectrum monitoring. The analysis of signal power metrics performed in this work suggests that non ad-hoc GNSS measurements from LEO could be exploited for GNSS spectrum monitoring.
{"title":"Interference Effects on a Multi-GNSS Receiver On-Board a CubeSat in LEO","authors":"Austin McKibben, Ryan McKnight, Brian C. Peters, Zachary Arnett, Sabrina Ugazio","doi":"10.33012/2023.19247","DOIUrl":"https://doi.org/10.33012/2023.19247","url":null,"abstract":"Given the increasing number of critical applications relying on GNSS, GNSS spectrum monitoring is becoming more and more crucial. Monitoring from low Earth orbit (LEO) has been investigated, and interference-source geolocalization has been demonstrated. In this paper, results are shown from the Bobcat-1 CubeSat mission which recorded multi-GNSS measurements but was not optimized for spectrum monitoring. The analysis of signal power metrics performed in this work suggests that non ad-hoc GNSS measurements from LEO could be exploited for GNSS spectrum monitoring.","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":"135483172","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}
Governments and industries seek autonomous and resilient systems in a world becoming increasingly dependent on digital, interconnected technology. A key example of such is PNT, a fundamental and indispensable utility across the most essential market sector for everyday life. However, PNT is under threat from hostile actors and changing politics, and a system-of-systems approach is required for its delivery. For timing infrastructure, atomic clocks are commonly considered. A network of ground-based atomic clocks support the distribution of the UTC time standard globally. Units have also been utilized onboard multiple GNSS satellites to support timing and ranging services. However, atomic clocks are costly to manufacture, and are demanding to system resources. These challenges have presented significant supply and implementation issues to various nations seeking resilient infrastructure. Atomic clock resource requirements have also led to failures across most GNSS constellations. The focus of this article is the provision of timing by pulsars, a natural source of frequency measurement. Millisecond pulsars in the RF spectrum are highlighted, given much stricter requirements for the measurement of X-ray pulsars on-board a spacecraft. Detection of multiple pulsars are challenging, and so only a single pulsar is considered to synchronize a lower performing clock. The work treats the scenario of lunar PNT, but it may be implemented across other PNT systems. Utilizing a large, origami folded radio antenna deployed on a spacecraft, it could potentially deliver timing performances below 1 µs independent of a synchronization source.
{"title":"Pulsar Timing for Clock Stability – Exploring an Autonomous and Resilient Approach to Timing Using Radio Pulsars","authors":"Joshua Critchley-Marrows, Xiaofeng Wu, Charleston Ambatali, Shinichi Nakasuka","doi":"10.33012/2023.19253","DOIUrl":"https://doi.org/10.33012/2023.19253","url":null,"abstract":"Governments and industries seek autonomous and resilient systems in a world becoming increasingly dependent on digital, interconnected technology. A key example of such is PNT, a fundamental and indispensable utility across the most essential market sector for everyday life. However, PNT is under threat from hostile actors and changing politics, and a system-of-systems approach is required for its delivery. For timing infrastructure, atomic clocks are commonly considered. A network of ground-based atomic clocks support the distribution of the UTC time standard globally. Units have also been utilized onboard multiple GNSS satellites to support timing and ranging services. However, atomic clocks are costly to manufacture, and are demanding to system resources. These challenges have presented significant supply and implementation issues to various nations seeking resilient infrastructure. Atomic clock resource requirements have also led to failures across most GNSS constellations. The focus of this article is the provision of timing by pulsars, a natural source of frequency measurement. Millisecond pulsars in the RF spectrum are highlighted, given much stricter requirements for the measurement of X-ray pulsars on-board a spacecraft. Detection of multiple pulsars are challenging, and so only a single pulsar is considered to synchronize a lower performing clock. The work treats the scenario of lunar PNT, but it may be implemented across other PNT systems. Utilizing a large, origami folded radio antenna deployed on a spacecraft, it could potentially deliver timing performances below 1 µs independent of a synchronization source.","PeriodicalId":498211,"journal":{"name":"Proceedings of the Satellite Division's International Technical Meeting","volume":"117 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":"135483173","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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