In traffic engineering, speed is the basic and important data for measuring and evaluating road performance and traffic conditions. Speed measurement by radar is one of the speed measurement methods that are easy to carry and have high accuracy. Its principle is mainly to apply the Doppler effect, that is, the moving object has a frequency shift effect on the received electromagnetic wave. The radar speedometer is based on the calculation of the frequency shift of the received reflected wave to obtain the moving speed of the measured object. At present, it is mainly used in traffic police patrol cars and so on.