Block I: GNSS
Fundamentals of GNSS I & II
The first part of the class will introduce the general concepts of Global Navigation Satellite System and will present its 3 key segments: space, ground and user segments. The course will continue with the description of the transmitted GNSS signal structure, the satellite/user propagation channel characteristics (satellite payload and antenna, free space loss, ionosphere, troposphere, multipath, interference, user antenna and receiver RF front-end) and the receiver signal processing architecture. This part will end with the provision of the GNSS receiver measurements' characteristics. Finally, the Position, Velocity and Time (PVT) computation based on Least Square will be introduced together with its expected performance.
Differential Positioning: DGNSS, RTK and PPP
This lecture presents the key principles associated with high accuracy differential GNSS positioning. After briefly reviewing the relevant concepts of GNSS positioning, the lecture presents the different measurements and error sources that limit positioning accuracy. The geographic and temporal variability of the errors will be addressed, as appropriate. Once the GNSS errors are understood, focus turns to mitigation of these errors through measurement differencing, linear measurement combinations, and different augmentation approaches (i.e., DGNSS, RTK, NRTK, and PPP). The motivation for these approaches will be explained in the context of trying to mitigate errors and resolve the carrier phase ambiguities. Mathematical formulations for the various augmentation approaches are introduced. Different augmentation message formats are also presented. The lecture will conclude with a discussion of the future prospects for the GNSS augmentation technique.
This course will provide an overview of the threats to safe, reliable, and continuous use of GNSS. These vulnerabilities will be divided into four classes: GNSS satellite and control segment failures, atmospheric anomalies (ionospheric and tropospheric), local environmental anomalies (e.g., unusual multipath), and RF jamming and spoofing. The threat posed by each vulnerability to integrity, continuity, and availability will be described along with mitigation technique for user and augmentation systems. Several examples of specific anomalies that have occurred will be discussed along with lessons learned from them.
Practical signal processing for GNSS: focus on interference
This component will go through the fundamental acquisition and tracking operations within a GNSS receiver, leveraging the Matlab open source code from the textbook and working with actual GPS/GNSS data to better understand the acquisition and tracking process. Students will work with live data sets, understanding the trade off in acquisition settings/parameters as well as tracking loop settings/parameters. The course will culminate with processing live data with RFI to understand the impact of interface within the receiver signal processing. Student will be asked to process this data and explore modifications to the signal processing to handle the RFI within the collected data. In addition, details on RF radio front end design will be presented, including the automatic gain control (AGC) component which can be extremely useful for assess the operational environment of a GPS/GNSS receiver.
BeiDou: This lecture provides an update on BeiDou Navigation Satellite System (BDS). It will provide a system overview of BDS, summarize current/planned characteristics and performance of BDS, report recent BDS’s programmatic events, update BDS schedule and plans, and summarize BDS ongoing interactions with other GNSS service providers.
GPS: The so-called ‘GPS Modernization’ effort actually began in the mid 1990s as civilian users clamored for a second civil frequency and military planners sought spectral separation of military and civil signals. The result was a new military code (M-code) and three new civil signals (L2C, L5 and L1C). This seminar will describe the details of the new codes along with their status in the current constellation.
Opportunities of MCMF Positioning
The lecture provides an overview of positioning with GNSS Multi-Constellation and Multi-Frequency (MCMF). The present and future signals of the GPS, including C/A-code, P(Y)- code, L2 civil (L2C), L5, M-code, and L1 civil (L1C) will be detailed, as will the signals for GLONASS, Galileo, BeiDou, satellite-based augmentation system (SBAS), and other emerging satellite navigation systems. Positioning performance with various measurement inputs and modes (static, kinematic, single- / dual- / multi-frequency, single- / multi-constellation) will be investigated. Key problems need to be solved for MCMF positioning will also be discussed.
Reliability of GNSS positioning
This course will describe how the reliability and safety of GNSS positioning is assessed and protected for both standalone and augmented users. The reliability of GNSS navigation will be defined in the standard terms of accuracy, integrity, continuity, and availability, and the impact of each of these performance characteristics on safe and trustworthy navigation will be explained. The concept of protection levels calculated by users to bound GNSS errors to small probabilities will be described along the algorithms and monitors required to support and generate protection levels for both standalone and augmented users. The levels of performance that users can expect from different applications of GNSS (e.g., level of augmentation, use of multiple constellations and frequencies) will be demonstrated.
Block II: Multi-Sensor Navigation
Introduction to Kalman Filtering
Since being introduced in 1960, the Kalman filter has become the primary algorithm employed by integrated navigation systems such as GNSS-aided-inertial systems and so-called multi-sensor navigation systems. This seminar will provide a comprehensive introduction. Fundamental concepts from estimation all the way up to inertial aiding will be explored in the intuitive context of scalar examples.
Inertial navigation relies on the determination of linear acceleration from specific-force measurements and the determination of angular rotation from so-called gyroscopes. This seminar will describe the algorithms needed to process these measurements to determine orientation, velocity and position. Error characteristics will be explored along with the techniques used to perform system initialization.
Vision-and Laser-based Navigation
This lecture discusses various approaches that use laser-based sensors (e.g., laser range scanners) and vision sensors (e.g., RGB cameras) for navigation in difficult urban and indoor environments where the performance of typical Global Navigation Satellite System (GNSS) receivers is deteriorated. The navigation technologies presented are laser- and image-aided inertial and Simultaneous Localization and Mapping (SLAM) methods using laser and imaging sensors. Topics included are the basic principles of integration with inertial sensors; vision- and laser-inertial integration mechanizations; the use of correlation techniques, feature-based techniques or optical-flow-based techniques; the use of a priori information such as terrain and feature databases; and SLAM approaches.
Signals of Opportunity
Signals of opportunity are signals that are used for positioning, while they have not been deployed or designed for a positioning service. They can be a useful back-up to GNSS in urban environment. This lecture will describe the concept of using such signals for positioning and will give 3 examples : positioning using digital TV, 4G signal and WiFi signals.
Lab on vision-and laser- based Navigation for UAV
In this lab, we will demonstrate some of the techniques discussed in the lecture on vision- and laser-based navigation. The students will work with real laser-range scanner data and camera data to implement parts of the algorithms illustrated in the lecture and analyze the performance of the algorithms as a function of the various integration filter tuning parameters.
Probabilistic Robotics Navigation
In this lecture, we extend what we heard previously on Kalman filters, inertial and visual sensors, and laser based navigation to merge everything into a multi-sensor fusion framework. In particular, we will discuss the issues of multi-rate and multi-delay, estimator consistency, and computational complexity when using multiple heterogeneous sensors. We will further look at the possibilities of self-calibrating/self-initializing the extrinsic states that are introduced to the system with each sensor (e.g. GPS-IMU distance, elevation of the Earth magnetic field vector, etc). This allows us to dive more into the non-linear observability analysis and unobservable modes of a multi-sensor system including the decomposition of regular sensors into elemental sensors which can be arbitrarily combined for a quick intuition about the observability of the system.
Block III: Applications
Autonomous navigation of robots is a hot topic in many fields both in research as well as in industrial development. While autonomous cars are already in use and manufactured, augmented reality applications with indoor navigation capabilities are growing on the marked, and autonomous drone navigation is on the verge of getting out to industry. In this talk, we will discuss that robotics navigation is, in fact, a problem of solving perception. In this view, we will talk about the challenges caused by the environment and the specific requirements in terms of accuracy, reliability, and short and long term issues. We will highlight current solutions already used in industry,
The development of Civil applications for RPAS raise an issue concerning their integration in the Civil airspace. Of course, the main objective is to maintain a high level of safety.Some technologies and operational procedures coming from manned aviation could be used but there is a need of new solutions. In particular, the "See and Avoid" performed by the pilot has to be replaced by some "Detect And Avoid" capabilities. RPAS are versatile: concepts of operation between small and large RPAS, very low level flights (VLL) and very high level flights (VHL) will be different.
In this classe, we will explain the problem of airspace traffic management, then we will present some proposed solutions to integrate RPAS. Some on-going projects and experiments will be used to illustrate and clarify specific points.
The presentation will address the difficulties and stakes for GNSS solutions developments. It will underline the market expectations demodulated into technical objectives and features, while pointing out the main challenges, generally due to the quality of service that is requested whatever the conditions of use are.The presentation will illustrate these challenges based road market for GNSS. The presentation will detail the technical features that are mandatory for a strong market development (quality of service, integrity, reactivity, accuracy, etc…) as well as the main issues GNSS has to face, especially linked with the propagation environment.
Since its introduction in Aviation in the mid-90s, GPS has never stopped spreading around the world, increasing aircraft capacity to navigate on more direct routes, independently of the ground navaids network and enabling precision approach and landing. The International Civil Aviation Organization has recommended the wide use of GNSS for Navigation and its use for Surveillance is also promoted, as new signals are emerging around the world, including their augmentations such as SBAS and GBAS.
Future Air Traffic Management concepts identify performance based operations, that cover all phases of flight, gate to gate, including the Cruise phase, Precision Approach in all weather conditions as well as surface navigation. As these functions are developed, Aviation community must face the challenge that Aviation Operations are more and more demanding as they require enhanced accuracy, integrity and continuity while maximizing availability, in order to enable more stringent operations in terms of aircraft separations and minima.
But, why do we need integrity monitoring when using GPS in civil aviation compared to the use of older radionavigation aids ? How can we relate the essential airworthiness needs with the GPS system design and the airborne algorithm requirements ? What are the basic principles to derive requirements of integrity monitoring for civil aviation and how will they be applied in the future ? We will introduce the basic notions of reliability and confidence, applied to civil aviation, by providing the historical and regulatory background as well as explain key definitions of integrity monitoring focusing on GNSS. Using these fundamental notions, we will explain the links between the safety of the operation and the GNSS integrity monitoring requirements as they exist today and present the challenges faced when trying to implement more stringent operations using new or future GNSS. Finally, after having presented the history, technologies and needs of Civil Air Navigation, we will describe the main applications of GNSS in Civil Aviation with their benefits, looking at the challenges posed by interference and space weather and the expected benefits and challenges of Multi-Constellation GNSS.
Search and Rescue
The Search and Rescue classes will present the Cospas-Sarsat program focusing on the MEOSAR transition. A status of MEOSAR development will be presented as well as the development of the second generation of distress beacon. Finally, the context of in-flight distress activation will be presented highlighting how the MEOSAR system can bring solution to this new ICAO requirement.