What is the principle behind camera-based speed detection?

[Julian]

Most systems use radar to detect vehicle speed. When a vehicle enters the detection range, the radar emits two waves to determine the vehicle's position. After both waves are received, the distance traveled is calculated using trigonometric principles. Dividing this distance by time yields the vehicle's speed. If the calculated speed exceeds the predefined threshold in the system, the camera is immediately triggered to capture an image, making it impossible to hide speeding behavior. Currently, the mainstream international technology combines high-speed cameras with radar. Speed measurement principle: The speed measurement principle is a term from physics, determining whether a vehicle is speeding based on its velocity when passing parallel induction loops, with photographic evidence captured. The drawback of this method is the significant construction effort required to install induction loops in the road. If the road surface is altered, the loops must be reinstalled. Additionally, maintaining these loops is challenging in high-latitude regions during thawing periods, low-latitude regions in summer, and areas with poor road quality. Ultrasonic distance measurement principle: An ultrasonic emitter sends out ultrasonic waves, and the distance is determined based on the time difference when the receiver detects the waves. This principle is similar to radar distance measurement. The ultrasonic emitter sends waves in a specific direction while simultaneously starting a timer. The waves travel through the air and bounce back upon hitting an obstacle. The ultrasonic receiver stops the timer as soon as it detects the reflected waves.