Radar

Accident data show that more than 76% of accidents are caused solely by human error; and in 94% of accidents, human error is included. ADAS (Advanced Driver Assistance Systems) is equipped with several radar sensors, which can well support the overall functions of unmanned driving. Of course, it is necessary to explain here, RADAR is called Radio Detection And Ranging, which uses radio waves to detect and locate objects.

Current radar systems generally use 24 GHz or 77 GHz operating frequencies. The advantage of 77GHz lies in its higher accuracy of ranging and speed measurement, better horizontal angle resolution, and smaller antenna volume, and there is less signal interference.

Short-range radars are generally used to replace ultrasonic sensors and support higher levels of autonomous driving. To this end, sensors will be installed in every corner of the car, and a forward-looking sensor for long-range detection will be installed on the front of the car. In the 360° full coverage radar system of the vehicle body, additional sensors will be installed in the middle of both sides of the vehicle body.

Ideally, these radar sensors will use the 79GHz frequency band and 4Ghz transmission bandwidth. However, the global signal frequency transmission standard currently only allows 1GHz bandwidth in the 77GHz channel. Nowadays, the basic definition of radar MMIC (monolithic microwave integrated circuit) is “3 transmitting channels (TX) and 4 receiving channels (RX) are integrated on a single circuit”.

A driver assistance system that can guarantee L3 and above unmanned driving functions requires at least three sensor systems: camera, radar and laser detection. There should be several sensors of each kind, distributed in different positions of the car, and work together. Although the required semiconductor technology and camera and radar sensor development technology are now available, the development of lidar systems is still the biggest and most unstable challenge in terms of technical and commercial issues.