For Self-Driving Cars, the Hot New Technology Is… Radar

Radar, which bounces radio waves off objects—the term was born as an acronym for “radio detection and ranging”—has been used on some first-generation safety systems in vehicles since the 1990s. Automotive radar systems have a number of advantages. They’re tough enough to survive years of jostling and temperature swings when mounted on cars. They’re much, much less expensive than lidar, good at instantaneously measuring the velocity of objects, and able to peer through the kinds of inclement weather, like fog and rain, that can foil both cameras and lidar systems. But they have until recently had one major drawback: They have only a fraction of the resolution of those other systems, which means in essence that the images they produce are much blurrier.