1, installed on the crossbar above the middle of the road, measures the speed by illuminating the lane obliquely downward;

2, installed on both sides of the road, through the horizontal angle with the lane for speed measurement.

According to the principle of radar velocimeter, when the direction of radar velocimeter is consistent with the direction of vehicle movement, in this case, the vehicle will not shoot when it is close to the radar velocimeter, and only shoot when it is far away from the radar velocimeter, and shoot at the rear of the vehicle; When the facing surface of the radar speedometer is opposite to the moving direction of the vehicle, in this case, the radar speedometer photographs the front of the approaching vehicle and the moving vehicle.

Radar velocimeter measures speed by emitting electromagnetic waves. When the electromagnetic wave touches an object, it will be reflected back and re-received by the radar velocimeter. If the object is moving towards or away from the radar velocimeter, the reflected frequency of electromagnetic wave will be different from the reflected frequency, and the data processing center of the radar velocimeter will calculate the speed value according to the frequency difference. The ideal speed measuring method of radar velocimeter is to aim the transmitting end of radar velocimeter at the measured object, and its axis is in the same line with the moving direction of the object, so that the speed value of the measured object can be measured whether it is near or far from the radar velocimeter. Therefore, radar velocimeter can measure near or far objects.