The Applied Research Of MSK Modulating Technology In The Digital Track Circuit

Along with time's development, Developing automatic train control system (ATC-D) based on digital coding track circuit of proprietary intellectual property is imperative.The track circuit is a very important part in train automatic control system (ATC) which is affecting the signal quality directly and it guarantees the traffic safety and enhance transportation efficiency.Based on research of domestic and foreign digital coding track circuit, it proposes a kind of digital coding track circuit technical plan suiting our country's national condition: Based on the UM71 track circuit, uses MSK (Smallest Frequency-Shift Keying) modulating technology to realize transmission of information on the track circuit.And discusses feasibility of the MSK modulating technology to apply in this plan .In the article also make the detailed introduction to software and hardware design to realize this plan.The master control CPU has selected ATMEL Corporation's AT89S52 in hardware design.Through it real-time control to the Direct Digital Frequency Synthesizes (DDS) chip AD7008 to produce the MSK signal,then the signal must pass through the amplifier to enhance the purity and to achieve its technical specification.In the hardware design it also used real-time examination to output signal to increase the system's reliability.The software design uses the order compiling method and divided into six modules of the establishment start code,the system initialization subroutine,the serial port correspondence subroutine,the data processing subroutine,the watch-dog monitoring design and feed back examination to compile the procedure separately.It has realized each part of functions separately through the debugging and further has confirmed the plan's feasibility.