Research And Realization Of Subway Train Communication Network

Up to the present, all the vehicles in Guangzhou No. 1 subway line are imported from abroad and the corresponding vehicle bus was developed by Siemens Company. However, the vehicle bus has been in operation for 10 years. To solve the problems of equipment aging, expensive spare parts and long procurement cycle for Guangzhou No. 1 subway line; and to optimize and upgrade the existing vehicle bus by home-made technology, an improved vehicle bus controller has been developed and implemented in this thesis.According to the vehicle bus protocol specification of Guangzhou No. 1 subway line this paper has designed the soft-cores of the data link layer and physical layer with independent intellectual property rights based on FPGA. Data link layer soft-core is mainly composed of the first-in-first-out (FIFO) module, cyclical redundancy check (CRC) module and serial-parallel converter module. FIFO module is used for solving the issue of asynchronous clock read and write cache; CRC module checkouts both data of sender and receiver; the serial-parallel converter module is used for the data conversion between the 8 parallel data and serial data. The soft-core of physical layer is used for completing the converter of NRZ and Manchester codes and getting bit synchronous clock from Manchester codes. Bit synchronization clock is not only the reference clock of codec module, but also the reference clock of data link layer module after the second sub-frequency. This paper adopts the method that constructs a phase-locked loop in the FPGA-chip to achieve extraction of bit synchronous clock. This program has a strong anti-interference ability, and it is not easy to lose the lock. Meanwhile, the Soft-cores are described by VerilogHDL and integrated, compiled, placed and routed by the Quartus II 8.0. Finally they are simulated functionally by Modelsim 6.0.Further, the experiment research has been done based on the simulation analysis. The experimental results show that the improved vehicle bus controller can work well and satisfy the requirements of Guangzhou No. 1 subway line. Meanwhile, the redundancy existed in the vehicle bus developed by Siemens Company can be reduced by the proposed controller in this thesis; therefore, the vehicle bus circuit can be simplified and become more efficient. Thus, the research in this thesis has great significance for improving the home-made technology of vehicle bus.