Low bandwidth signals for LIDAR

• Autor(a) principal: Bastos, Daniel António Macedo
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/28323
• topic: LIDAR; Continuous wave modulation; Interference; Optical communications

During the last few years there has been a significative increase of the study and development of autonomous driving systems, in order to have a lower rate of car accidents in the future. One of the main functions necessary for a good performance of this type of systems is the detection and distance estimation of a potential obstacle. This can be achieved through the use of LIDAR (Light Detection and Ranging) technology, within which the most used application is the pulsed LIDAR, for which a direct measurement of the time-of-flight of pulses, which are transmitted by a laser, reflected at an obstacle and captured by a receiver, is done. However, the cost and complexity of this type of implementation are still too high. Throughout this thesis, another type of LIDAR technique known as AMCW (Amplitude-modulated Continuous Wave) was then explored, for which continuous signals are amplitude-modulated and for which a good precision was obtained for the estimation of distances of an obstacle up to 300 m. This technique introduces the possibility of a reduction in cost and complexity of this type of system. Different ideal and non-ideal cases were simulated for two estimation methods e for different types of waveforms, in order to understand which parameters and working conditions enable the optimization of the system. Another great focus of this thesis was the influence of the presence of interferences, originated from other LIDARs, on the estimation methods. From the obtained results, it was observed that even for scenarios with the presence of various interferences, the system is capable of making estimations with an acceptable absolute error. Lastly, the possibility of implementing a communication system in cooperation with the studied estimation system without losses in estimation quality, was tested. It was concluded that this implementation is possible, guaranteed that some conditions relative to the transmitted signals are respected.