Signals And Telegrams Detector For CTCS Balise-Design Of Telegram Decoding And Upper Computer Software

The Balise Transmission System is a spot transmission based system, which providesthe safe service of information transmission between the wayside infrastructure and thetrain. To be the important component of the Train Control System, it guarantees therunning train against potential dangers. The Balise and LEU(Lineside Electronic Unit),which are the main equipments of the Balise Transmission System, convey thetelegrams formatted by the Train Control Centre to the train. The telegrams, composedof the safety related information about the sections of lines in railways, have the directrelation with the train. It is, therefore, urgent to maintain the failure of the Balise andLEU.Aimed at solving the safety issue discussed above, this thesis introduces a design ofinstrument for detection of signal parameters and intercepting code message on theinterface ‘C’ and ‘A’, based on the principle of the Balise Transmission System. Thekey features of the tester include:(1)testing the amplitude and frequency of DBPLsignal on interface ‘C’, and acquiring the code message through DBPL demodulation;(2)sampling the FSK signal on interface ‘A’ by simulating a tele-powering signal withthe frequency of27MHz used for activating the Balise, and extracting the code messagefrom the output of FSK demodulation after waveform shaping through the channelcircuit. The signal data and code message are stored in the data buffer under the controlof CPU on the tester mainboard, then the CPU estimates the offline state of the cable oninterface ‘C’ by computing the stored data in buffer; the contents of telegram aredisplayed on LCD after the procedure of decoding and resolving for code message. Alltesting data will be saved in the memory on tester under the operation of user.The suitable software on PC is designed in Lab Windows/CVI IDE to facilitate theuse of tester. The upper computer software communicates with tester through serial port.The several function modules are uploading of data records, management for database,records retrieval, report management, data analysis, etc. Multi-thread technique isadopted in the process of measurement online and sync uploading of records. Moreover,the upper computer software has the integrated function, as well as the better stability. This thesis mainly focuses on the implementation of the software decoding for Balisetelegram, instead of hardware decoding, base on the analysis of the Norm of FFFIS forcoding and decoding. The software decoding has slower speed compared with hardwaredecoding; nevertheless, it has the advantages of lower cost of portable handheldinstrument with the features of low-power microprocessor and excellent computingperformance. In the application of test, the technical specification of decoding for codemessage meets the requirements expected, so does the handheld tester.The innovation of this thesis is proposing the method of software decoding for Balisetelegram. An improved optimizing method is introduced for the decoding, on thepremise of satisfying the design requirements, to avoid the defect of time consumptionin extreme case. Above all, some achievements are reached about decoding for Balisetelegram.