| With the rapid development of high-speed trains,the train is running faster and faster,which brings convenience to people’s life,and also causes people to pay attention to the safety of train operation.Transponder most as a high-speed point data transmission equipment,for train safety operation to provide line slope information,temporary speed limit and positioning information data,plays an important role in the train operation control system,so the reliability of railway transponder is an important premise to ensure the safe operation of trains.The traditional transponder test platform is large,expensive,low portability,and for the on-site transponder failure can only be returned to the factory for maintenance,greatly increasing the troubleshooting cycle.Taking the above factors into consideration,based on Lab VIEW as the host computer,this paper develops PXI(PCI extensions for Instrumentation)system board,and designs and develops miniaturized transponder test bench based on the basic framework of production and consumer.The feasibility of the test platform and the accuracy of the test results are comprehensively verified by using the practice unit’s independent transponder product and the third party manufacturer’s product.(1)First,according to the working principle of the transponder transmission system,analyze the transmission characteristics of the uplink signal of the transponder.With reference to the test specification of railway industry standard TB/T-3544 and SUBSET-085 of the People’s Republic of China,a miniaturized transponder test platform shall be built,and the test index of transponder product and the design scheme of related index shall be determined.After long-term research,comprehensive consideration of performance,price,scalability and other factors,because the PXI platform and Lab VIEW programming language in the field of automated test development has obvious advantages,so the development and design of the test bench is based on Lab VIEW as the upper computer development NI PXI system board card to complete the overall design of the test bench.(2)Download the driver program according to the actual engineering application,complete the initialization and parameter configuration of the instrument according to the triggering mode and triggering sequence of the instrument.After the preparation work was completed,the program of IQ signal acquisition on the uplink of the transponder and the demodulation of IQ signal were designed,and the corresponding index data processing was completed.By analyzing the advantages and disadvantages of common FSK signal demodulation methods and considering the performance,anti-interference and implementation difficulty of the demodulation algorithm,this paper adopts the phase demodulation algorithm to demodulate IQ signals.Through the inverse tangent solution of I signal and Q signal,the phase continuous design is carried out,and finally the phase transition point is found point by point.This method makes the results of signal demodulation more excellent.In order to further optimize the signal quality,this paper also adds the moving average algorithm to make the data processing results more accurate.(3)After the overall design of the miniaturized transponder test platform was completed,the practice unit transponder product was used for verification test,and Word version test report was added to the test results,including electrical equipment type and manufacturer,graphic test results of related test indicators and test results evaluation,etc.Compared with the traditional test bench,the results are correct and the scalability of the test bench is stronger,which can realize single board and whole machine test. |
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