| Train operation control system is the core to ensure the safe and efficient operation of trains.Among them,the balise transmission system is an important part of the train operation control system.It is set in the middle of the track to send the line basic parameter information,line speed information,temporary speed limit information and positioning information to the running train.Therefore,the balise plays an important role in ensuring the safe operation of the train.The active Balise and the Lineside Electronic Unit communicate by a special data transmission cable.In order to improve the signal transmission quality of the Balise control interface and ensure the reliable transmission of train control safety information,this thesis analyzes the transmission characteristics of cable,models and simulates the communication channel of the Balise control interface,puts forward the optimization scheme of the transmission system and carries out experimental verification.(1)Firstly,according to the composition structure of Balise transmission system,the working principle of the active Balise,the Lineside Electronic Unit and the physical composition of control interface cable are analyzed,and the communication channel model of Balise control interface is built.Considering the influence of cable proximity effect and skin effect,the eddy current field simulation model is established for the thickness of cable filling layer and dielectric information,and the resistance and inductance of unit cable are obtained.According to the open circuit impedance calculation equation of the transmission line and the measured impedance,the capacitance and conductivity of the unit cable are obtained.The cable transmission model is built based on the transmission line theory,and the simulation results are verified by practical tests.(2)C interface signal transmission and processing.The signal transmitted from the Lineside Electronic Unit to Balise consists of two parts,namely C1 signal and C6 signal.According to the characteristics of C1 signal,this thesis proposes a segmented transmission processing method of C1 signal.The C1 interface signal is regarded as the combination of two periodic signals and transmitted to the receiving end of the Balise in segments,so as to determine the signal time point and improve the signal frequency resolution.(3)The Balise control interface channel model is verified by using the return loss network test specified in SUBSET-085 standard.The correctness of the channel model is verified by comparing the consistency between the calculated value and the measured value of the network output signal.The eye diagram analysis method is used to evaluate the digital signal quality of the transmission system.For the large amount of data information contained in the eye diagram,the eye height and jitter time of the eye diagram are extracted by K-means clustering algorithm,and the bit error rate of the output signal is calculated.Compare the transmission quality of cable signals with different transmission lengths,and analysis the influence of different transmission conditions on the signal quality.(4)Aiming at the influence of channel on signal transmission quality,an LMS adaptive equalization algorithm with improved convergence constant is proposed.The functional relationship between convergence constant and error value is fitted through regularization model,and the weight of equalizer is adjusted in time according to the error value between output signal and expected signal,so as to compensate the influence of channel transmission on signal,improve signal transmission quality,and provide basis for the optimal design of Balise signal transmission. |
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