1,721,022 research outputs found
Application of the SDR technique to the GNSS world: Improvements to realise a complete receiver
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A multi-sensor autonomous integrity monitoring approach for railway and driver-less cars
No full textAutonomous driving technology requires high accuracy and high integrity position and navigation. No individual technology can currently meet these requirements anywhere, anytime and under any condition. Sensor fusion is considered as the go-to-solution for the development of fully autonomous driving technology. GNSS is an element of a sensor fusion based navigation system that includes lidars/radars, inertial sensors and cameras. This work shows as the comparison between the speed’s vehicle calculated by odometer and one estimated by GNSS receiver installed on board of train through Doppler is an effective means to face multipath in railway environment, even when just one receiver is available. Moreover, the georeferenced knowledge of the railway is not essential when Doppler are compared, while the pseudorange comparison requires a guess of the baseline between the receivers. Moreover, the proposed multipath detection and exclusion method is fully compatible with other techniques for multipath mitigation. The outcomes of this work, undertaken for railway scenarios, can be partly exploited in driver-less car applications thanks to the analogies between these two transportation sectors
GNSS Integrity Monitoring for Rail Applications: two-tiers method
No full textThe paper presents an innovative GNSS fault detection and exclusion approach for the adoption of satellite localization in the rail sector. Current global integrity monitoring systems cannot guarantee the safety level needed for such applications as train control where Tolerable Hazard Rate in the order of 10 is required. A new method, named 2-tiers, enabling to integrate local augmentation systems and global augmentation infrastructures, is presented. It is based on the comparison of single differences residuals among satellites for detecting signal in space faults and double difference residuals among local augmentation stations and SBAS RIMS for detecting reference stations faults. GPS SIS faults described in literature and real GNSS raw data recorded on a train are taken into account. The present work reports the performance analysis for the 2-tiers approach carried out during relevant European projects. A Test-Bed architecture has been developed through the implementation of the algorithm in real-time on a local augmentation operational centre. Relevant performances have been tested on a rail track for validating the algorithm in real operative conditions. Significant results of the analysis are reported for SIS integrity assessment only
An early-warning aerospace system for relevant water bodies monitoring
No full textThe study of water systems under multiple stress conditions involves the generation of complex models allowing users to make predictions. Nevertheless an effective monitoring system preventing risks of contamination for relevant water bodies doesn't exist yet. Currently smart integrated aerospace tools revealed high capabilities for 'early warning' of critical events and collaborative decision making on natural disasters. Their flexibility can thus successfully be applied to water monitoring scope integrating brilliant hi-tech solutions like advanced satellite platforms and drone technology. This paper describes a clever synergy and design of a powerful solution to overcome the limits encountered by some important stakeholders belonging to water sector in a prompt detection and in the effective transmission of the pre/post occurrence information to the competence centers, and from these, to the in-situ professionals
Space and frequency multiplexing for MM-wave multi-gigabit point-to-point transmission links
No full textDuring last 10 years, the use of frequencies at E-band from 71 GHz to 76 GHz, from 81 GHz to 86 GHz and from 92 GHz to 95 GHz to licensed users has been regulated in US, Europe, Australia and Japan. Due to the large amount of available bandwidth and reasonable atmospheric attenuation, these frequency bands are suitable for very high data rate radio communication for medium to long range wireless links. However, in order to convert the bandwidth availability into real capacity, suitable transmission techniques should be designed. In the present paper, we propose a space-frequency multiplexing technique using FDM, coded modulation and 4×4 MIMO spatial multiplexing for point-to-point multi-gigabit connection in the 81-86 GHz bandwidth. We tested the proposed system, considering different link distances, different values of pathloss and atmospheric and rain attenuations. Simulation results evidenced the possibility of achieving a 48 Gb/s net capacity over 5GHz bandwidth (spectral efficiency 9.6 b/s/Hz) with 99.98% availability at link distances up to 1 Km
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