Design Of Terminal Display System Applicated In Subway Station Of Urban Rail Transit

With the rail transit developing rapidly, terminal display system, as an important part of the whole rail transit must have capability of displaying high-definition video and audio real-timely, and must have strong reliability and stability. Because the signal interface and signal transimission of traditional terminal display system, it has a certain research significance and practice value to design a new type of terminal display system.The paper advances a scheme of terminal display system which transforms one road of SDI signal to five road of HDMI signal, and the system can process optical SDI signal and electric SDI signal compatibly. The hardware design adopts the architecture of combining ASIC and FPGA and consists of four parts which are SDI input processing, FPGA processing, HDMI hard-encoding and MCU controlling. SDI input processing transforms the input of HD-SDI or SD-SDI to parallel video and the IIS format of audio through the photoelectric conversion, signal equalization, audio de-embedding and SDI ringing back. FPGA processing encodes the parallel video and audio to one road of HDMI signal. HDMI hard-encoding transforms the parallel video and audio to four raods of HDMI signal, then driving them to four LCD. MCU controlling section achieves the functional configure of the system, entire system controlling and real-time debugging.During the stage of designing system PCB, excellent layout design, the power system scheme of combining DC-DC and LDO chips, and goog grounding scheme are applied to improve the system immunity on EMC. The system has been put into trial operation, and the results show the system can work stably and reliably, video and audio have good synchronization with high quality.So the system has achieved the design goals. At the same time, the system has passed three EMC testing, static discharge, fast transient group pulse and lightning, achieving the special requirements in subway station.