Automatic Vehicle Identification(AVI) has a wide application in highway toll system,parking charge,surveillance of city road and so on.In order to resolve problems of traditional AVI system such as low efficiency,complex structure,difficult installation,we discussed and realized a vehicle identification system based on ultrasonic ranging and BP neural network.The system is grounded on MCU, 485 BUS,gets vehicle datas and characteristic parameters from the ultrasonic ranging module,and gives the final result ...