Research On Parallel Ultrasonic Communication In Rail Without Channel Fading Compensation

Rail transit is one of the main transportation modes at present.The performance of the rail determines whether the train can run safely.Since the rail is in the open environment for a long time,it is easy to break,and the ultrasonic broken rail detection can effectively detect the rail break.However,the current ultrasonic broken rail detection system cannot transmit the basic information on the track.Therefore,this dissertation adds ultrasonic communication on the basis of the ultrasonic broken rail detection system,and proposes a parallel ultrasonic communication method without channel fading compensation in the rail.And a corresponding ultrasonic communication system is designed.Firstly,based on the detailed analysis of the principle of ultrasonic communication technology and Frequency-Division Multiplexing(FDM)technology,this dissertation proposes a communication method which is free from the modeling of rail channel.The reference signal is a signal with the same frequency and phase as the carrier signal.The reference signal is sent to the rail channel before communication and stored in the micro-processing system at the receiving end.In the communication process,the original signal is modulated by On-Off Keying(OOK).After receiving the modulated signal,it is demodulated with the reference signal stored in the previous stage to restore the original signal.This communication mode is simulated in MATLAB to verify the feasibility of the channel-free modeling communication scheme.Secondly,a corresponding ultrasonic communication system,including hardware and software,is designed for channel-free modeling communication scheme.The hardware part mainly includes the driving module,booster module and trailing absorption module at the transmitting end,and the pre-amplifying module and band-pass filtering module at the receiving end.The transmitter software is implemented in the Microcontroller Development Kit(MDK)environment,and transplanted to the STM32 in the transmitter board,which controls the transmission of the excitation signal through the serial port,and implements the demodulation algorithm of the correlation function through the STM32 processor in the receiver board.Finally,the functions of the hardware and software of the system are verified through field tests.The results show that the designed system can realize ultrasonic communication on the rail,which solves the problem that the broken rail detection system can not carry out more convenient and effective communication while detecting the broken rail.At the same time,FDM technology is also introduced in this dissertation,and the communication rate is up to 1.33 Kbps.The fast communication of the communication system is realized.