Cradar-an open-loop extended-monopulse automotive radar

A forward-looking, relatively inexpensive, onboard automotive radar called cradar, that senses the highway environment of the vehicle is described. The radar measures the range, range rate, and bearing angle of roadway targets. The radar has a proposed angular spread of approximately 17° and a range of 5-100 m. It uses a unique front end, designed to provide maximum information from a single small-aperture antenna. The antenna is time shared between three different driving waveguides modes, modes with quite different radiation patterns. Return signals are separated by mode and continuously parallel processed. Individual mode returns yield target signature characteristics, range, closing speed, and some bearing information. Cross-mode returns yield target bearing and hence transverse speed. It has some multiple and extended-target capability both on straightaways and on curves. Foreseen uses of the system include increasing safety by providing driver information, a smart cruise control for driver convenience, and direct longitudinal control of the vehicle on automated highways. These uses may help to increase the traffic-carrying capacity of existing highways