International audienceThis study presents a review of the state-of-the-art and a novel classification of current vision-based localisation techniques in unknown environments. Indeed, because of progresses made in computer vision, it is now possible to consider vision-based systems as promising navigation means that can complement traditional navigation sensors like global navigation satellite systems (GNSSs) and inertial navigation systems. This study aims to review techniques employing a camera as a localisation sensor, provide a classification of techniques and introduce schemes that exploit the use of video information within a multi-sensor system. In fact, a general model is needed to better compare existing techniques in order to decide which approach is appropriate and which are the innovation axes. In addition, existing classifications only consider techniques based on vision as a standalone tool and do not consider video as a sensor among others. The focus is addressed to scenarios where no a priori knowledge of the environment is provided. In fact, these scenarios are the most challenging since the system has to cope with objects as they appear in the scene without any prior information about their expected position

International audiencePrediction and analysis of GBAS integrity monitoring is important, especially at the airports where a GBAS station it to be installed. Based on existing standard documents and published research, we present a software tool for GBAS availability prediction. Simulations have been conducted that include single point, single approach path, and multiple repetitions of a same approach path in order to analyze the availability of GNSS signal integrity monitoring with a GBAS at LinZhi airport. The results show that the long-term 24-h service availability figure at two typical single points along the approach path for GBAS Approach Service Type C (GAST C) is above 99.999 % for each point, and for GBAS Approach Service Type D (GAST D) at three typical single points, it is lower than 99.8 % for each point. The unavailability percentage over a 24-h period is 0.76 and 2.40 % for GAST C and GAST D, respectively. The results of sensitivity tests show that the impact of the mask angle and the latitude on the GBAS availability at LinZhi airport are more important than that of the constellation. Our conclusions could also be of interest for the implementation of GBAS stations at other plateau airports

International audienceAirport Navigation will require more stringent localization performance requirements than in-flight navigation [1]. GNSS signals (Global Navigation Satellites Systems) can be envisaged to elaborate the aircraft estimate position on the airport surface. To improve the performance of localization on the airport, the errors on GNSS signals particular to the airport environment must be characterized. Most of these errors are well known such as ionosphere error, troposphere error, etc, and do not depend on the airport environment. But to achieve the expected sub-metric performance, it is necessary to better model multipath error for which a model already exists but is valid for operations from en-route down to CAT I only. In this paper, an analysis of real GPS measurements (using code pseudo range measurement, carrier phase measurement, Doppler measurement and the estimate C/N0 ratio measurement) during taxiing operation on the airport surface is conducted. The goal of this paper is to evaluate when multipath occurs and to compare the multipath model (elaborated from the standard deviation of the measurement errors due to multipath) based on those collected measurements in the airport with different models proposed in the literature (not necessary proposed for airport navigation)

One of limitations of the current GNSS signals is their low data information rate. This low data information rate does not allow, for example, the transmission of additional commercial services or the transmission of redundant ephemeris data. The Code Shift Keying (CSK) is a signaling technique specifically designed to increase the transmission bit rate of a spreading spectrum signal. Therefore, one solution to increase the data information rate of the GNSS signals is to introduce the CSK technique in them. In this paper, the implementation of the CSK technique into GNSS signals is inspected through the development and analysis of the likelihood ratio expression of the bits transmitted inside a CSK symbol, and through the identification of the best mapping between bits belonging to a word and bits transmitted inside a CSK symbol.Finally, the impact of the CSK technique on the GALILEO E1 signal is analyzed by calculating the CSK demodulation performance for a given scenario and the drawbacks of the technique on the signal acquisition and tracking processes.