Research On Transmission Characteristics Of Digital Jointless Track Circuit

Since the beginning of the 21st century, the upsurge of our national construction of urban rail transit has come. In the various equipments of the urban rail transport, the track circuit equipment is very important. Because jointless track circuit can decrease the resistance and abrasion, and digital track circuit has advantages of high reliability and more information, use of digital jointless track circuit in urban rail transit is an inevitable trend in our country. But during the current use of digital jointless track circuit, the debugging was based on actual field conditions, lacking of theoretical guidance. Hence, theoretically analyses on the transmission characteristics of digital jointless track circuit and design software are of great theoretical and practical value.Since the signal equipments imported is unable to meet the development demand of urban rail transit, independent research of the domestic digital jointless track circuit is critical. Charateristic analysis for signal transmission of digital jointless track circuit was mainly studied in this thesis. Design digital jointless track circuit analysis software, which validated the transmission parameters could or not meet requirements of the normal, shunt and signaling states, was the key work of the research.Firstly, based on the principle of jointless track circuit and the transmission of four-terminal network, parameter models of rail line and cable was established, and their frequency characteristics were analyzed. The parameters of resonance transformer four-terminal network were also worked out in this paper. The transmission attenuation of track circuit which without, with uniform and concentrated compensating capacitor was analyzed, and the appropriate distance and value of compensating capacitor were ensured in this thesis.Secondly, based on analyzing and calculating the normal state of digital jointless track circuit, every voltage of transmission and the adjustment resistance were numerated in this thesis. Then every shunt points on the track circuit were checked that every shunt point shunt reliably, with no "dead section". At last, the cab signaling state was analyzed to make sure that the current in track could meet the requirements of cab signaling. The transmission parameters must be re-allocated until the track circuit could achieve the best which meet the requirements of the three states at the same time.Finally, on the base of analyzing track circuit, digital jointless track circuit analysis software was implemented by the GUI tool in MATLAB. The software analyzed the parameters inputed of track circuit, and got the adjustment resistance and every voltage of transmission, the shunted and cab signaling states were also validated in the software.