Millimetre-wave 3-D Imaging System for Collision Avoidance: a Digital Holographic Reconstruction on a Distributed Architecture

In order to realise an on-board anti-collision system able to work in any weather condition; a radar imaging system is needed It must acquire the 3-D radar image of the whole automotive scenario in front of the car with ultra high resolution; furlhermore in order to predict the trajectories of the obstacles, the system must acquire the speeds of them with high accuracy. These requirements cannot be reached, at millimetre frequencies, with phased array techniques; in fact to achieve high accuracy in angular position, large antennas have to be used so that the investigation volumefalls in the near-field region of the antenna where phased array is unable to image it At CESPA it is under development a project of an imaging radar system for anti-collision, called MIRANDA (Millimetre-wave Imaging RAdar in the Near fielD for Anti-collision). This architecture is based on four transmitters and a planar array of intelligent receiving cells, each one with the microwave front-end integrated with a DSP. These cells are digitally connected in chain by high-speed data links and their millimetre front-ends are coherently synchronised with the transmited signal. The reconstruction process is performed in a distributed manner on the DSP net, in order to obtain the images of the observed scenery and the speeds of the obstacles in real-time.