Study On Digital Transmission In Marshalling Yard Doppler Radar Speed Measurement

As the main part of the railway hub,Marshalling yard is used to separate railway cars to one of several tracks.Doppler radar speed measurement device is the main equipment in marshalling yard automation control system.The output of the traditional radar is square wave signal which is proportional to the velocity of running wagons.It is transmitted to the indoor speed measurement computer through the electric cable.The signal will be decayed and distorted after long distance transmission mainly because of low frequency analog signal.After the electrification innovation of the railway around and the tail of the marshalling yard,the radar speed measurement system for marshalling yard will be disturbed by electromagnetic interference.Therefore,radar speed measurement system may produce inaccurate data or could not work normally.Under this background,this paper puts forward a kind of digital transmission system for Doppler radar speed measurement.When the system processes signal from the Doppler radar in the field,calculates the speed value,then transfers it in a digital mode to the indoor control system through CAN network.In order to improve reliability and security of the digital transmission system,dual CAN bus which have the advantage of fault tolerance and reliability was chosen as the network topology.A kind of secure communication protocol for the CAN bus application-layer was designed and optimized,which meets EN50159 standard.STM32F105RBT6 which features dual CAN channel is selected as the main controller of the radar speed measurement,and its software is developed in Keil5.The slave computer is used to acquire and analyze data,the supervisory computer is used to control the data acquisition.The monitor software of supervisory computer is designed by Labview in which master CAN and slave CAN node of the radar speed measurement can be switched as needed.We can acquire and analyse the data through the designed layout.The whole system can achieve fault-safety ability and high reliability.