Research On Frequency-shift Signal Generator Of Railway Base On μC/OS-Ⅱ

As an important component of the train operation system, the smooth running of train signal equipment is directly related to the train operating efficiency and safety. Along with the effective implementation of the sixth large scale railway speed in China, the stability and reliability of train signal equipment are facing higher and higher requirements. As a result, both debugging and warehousing detection of train signal device are necessary and important tasks. With the development of technology, how to adopt new theories and technologies to solve problems encountered in the railway system is with great theoretical and practical significance.First, combining with the shortcomings of existing fat decoder's complicated operation, single function, uneasy to spot detection and crisis detection system debugging; this paper focuses on the current domestic locomotive signal detection and computer monitoring system debugging needs. Then, based on embedded system design and direct digital synthesis (DDS: Direct Digital Synthesizing) technology, it presents a network-enabled embedded device development method for fat decoder. This paper mainly includes five contents:(1)Through doing depth analysis to the characteristics of the existing track circuit in China, combining with the needs of the train signal equipment's on-site testing and system debugging, this paper studies and makes the functions and technical indicators of railway signal-generator clear.(2)Taking the needs of stability and reliability to signal equipment testing and commissioning into consideration, railway signal"failure- security"design principles are introduced into the system in this paper. Two sets of closed-loop detection circuit with the second taken two logical designs are taken into the system to ensure the system reliability and consistency of sending signals to achieve automatic detection of system failure.(3)Based on the principle of direct digital synthesis, this paper doing analysis on DDS signal from the two aspects of time domain and frequency. Meanwhile, it gives the theoretical value of the DDS signal noise.Besides, based on DDS technology within the FPGA platform, the system can fusil FSK signal output with high precision. Modular design can produce FSK signals output with different frequencies by changing the value of DDS accumulator. In other words, the system meets the requirements of common using.(4)Using modular design method for system hardware and software co-design, this paper proposes message transmission and remote control method based on CAN bus in order to improve system efficiency and enhance centralized management of testing equipment. The designs not only effectively shorten the design cycle, but also greatly enhance the stability of the system.(5)This paper does study onμC/OS-Ⅱsystem porting based on ARM7,and determines system's multi-tasking design. Thus, the system is able to ultimately sent a frequency shift signal in real time by multi- task scheduling ofμC/OS-Ⅱ.This paper proves the signal-generator based on embedded system design is stable, in real-time and reliable by doing room temperature, low temperature and high temperature tests on it. The system designed in this paper can sent most standard FSK signal in high precision. As a result, the system with strong universal can fully meet the requirements of train signal detection device and microcomputer testing system debugging.