Asymmetric Pulse Track Circuit Technology Study

Track circuit is one of the important railway signaling equipment to ensure traffic safety and traffic command automatic.The interlocking outside equipment is important for the railway communication system.It plays an important role in safe driving and shutting safety.For asymmetric pulse track circuit with strong anti-interference, high sensitivity shunt, stable, etc. Asymmetric pulse track circuit widely used rail surface corrosion, dirt and ballast resistor lower section.But in practical applications,the asymmetric pulse track circuit exposed some defects in scene, which the major problem is thyristor was easy to be damaged due to lack of pressure and heat when code generator without load will produce high voltage, and the insufficient of the dual two relay, they has not been able to meet the railway site need.To solve the above problems, the paper proposed a design of the asymmetric pulse track circuit receiver based on single chip on the basis of previous research and at same time code generator was made modified and. Protected Not only had the improvement in the equipment structure, but also had improved the performance significantly which also conforms to the development trend of the current railway signal and the automatic control system.The paper described in detail the structure of asymmetric pulse track circuit and working principle.Based on the existing equipment, in order to deal with these questions, the paper makes the main circuit structure, MCU features, A/D design and sampling methods and given the power module, serial communication module, JTAG interface module and other design ideas and circuit schematics and completed the hardware circuit design and PCB board production, also has completed the hadware circuit design and the software design and debugging.It introduced in detail on the softwar environments and the software design and analyzes the main program module, the interrupt subroutine module and serial communication module in the paper.Finally, the paper gives the hardware and software debugging method and procedure.The signal is processed by microcontroller, with processing speed, real time and accurate processing.This paper presents the ideal of safety redundancy design, which is double circuit board and double CPU. It improves the reliability has given attention to the effieieney simultaneously. When the main circuit board fails, the system will automatically detect and switch from the circuit board to work to ensure the safe operation of trains, reducing driving dangerous when it can not do timely maintenance. Also the code generator issued by a certain amount of protection due to make circuit stability.The thought and the design method which the paper propsoed to achieve the digital track circuit, and hope to avoid the problem of the poor shunt and reduce the "failure-security"hidden danger of the receiver circuit, improve the system anti-jamming capability (especially frequency interference protection capability), and experiments shows that, this program is feasible and it meet the needs of the railway site. Meanwhile, Circuit protection on the code generator is extremely effective, played a role in protecting code generator in the paper.lt has the transformation of simple, low investment, small size characteristics. Although the design of paper did not mature, but it has a good prospect.