Research And Design On Sending System In Digital Track Circuit

With the continuous development of high-speed railway, we have to constantly improve the traffic control accuracy of Train Control System in order to guarantee train's safety and improve work efficiency. The accuracy of the train control and the information provided by the train control center is closely related. The more precise para-meters, the higher control precision. The efficiency will also increase. Therefore, modern train control system can affect the quality of transmitted signals and used to ensure traffic safety and improve the daily operational efficiency is a key part of the track circuit. For these reasons, study on the digital coding track circuit is very important. This is significant for the development of auto-matic train control system in the name of China's intellectual property rights.This system is based on the digital track circuit.Purposes of this paper are:study the working principle of digital track circuit, and carry out system analysis and modeling. Study the parameters of main system design principles, and design a digital track circuit subsystem which is suit for China's national conditions. This paper, include the following aspects.In the paper, in-depth study of today's typical of the digital track circuit theory and technical parameters and design ideas, After overall study of currently existing several digital modulation methods and stimulating comparing, we got the most superior modulation.we have found a kind of digital track circuit sending system technical plan which is fit for our country's national condition.Based on currently existing track circuit, sending system uses the MSK Modern digital modulation techniques to achieve the listed control information in the track circuit transmission. About the feasibility of this program, the problem include the MSK modulation technique, we also did some deep study and simulating argument. This paper has clear explanation of hardware and software design plan, which is used in the digital track circuit system.This paper shows the main subsystems of the digital track circuit design of sending subsystem. System uses TI's TMS320VC5510 of the DSP, through the real-time control DDS ADS9851 produce MSK modulated signals. System software design using the traditional order of the preparation method, the system is divided into program loader,serial communication program, design of DDS driven program, design of watchdog program respectively, through Debugging achieved the commissioning functions of each part, further verify the feasibility of the program.The importance of this paper lies in:through combining the advantage of DSP and DDS chip and the modulation of MSK, apply these advantages into digital track circuit area of railway signal system, which can provide valuable exploration and experiment on selecting the mode of information transmission in automatic train speed control system.