In order to reduce traffic accident in road corner

design a warning system which can detect and measure speed of moving object on both sides of the road corner.The Doppler microwave sensor which has long detection distance

strong penetrability and can measure speed is chosen

and signal generated by the sensor is multi-level magnified

filtered

sampled and then used to make FFT to get its frequency

then speed of car and pedestrian is calculated

appropriate warning signal is displayed on the LED screen.The result of tests indicate that the detection distance of the system exceeds 40 m

range of speed detection is 0.5

73 km /h

which has effective warning effect and high practical value.