The Research And Application Of Digital Frequency Shift Signal Detection Method

With the rapid development of railway transportation, in order to ensure and improve thesafety and quality of railway transportation, a real-time detection technology of the frequencyshift circuit of the railway is needed, which allows us to get more information from operation ofrailway. Frequency shift circuit signal in real-time detection is an important prerequisite forensuring the safe and reliable rail transportation. The traditional frequency shift signal detectiontechnologies have been highlighted many of their own defects. Therefore, with the help ofmodern state-of-the-art microelectronics and computer technology, design a new railwayfrequency shift signal detection system to improve the efficiency of the frequency shift signaldetection, and protect the safety of railway operation is very necessary.In this paper, a design of portable railway frequency shift circuit is presented. The systemconsists of digital signal processors using FPGA, and supported by micro-controller designedby SOC. They complement each other, making the system with high integration, speed,flexibility, and practical.Railway signal is characterized by a wide range of frequencies, generally ranges from tensof Hz to several thousand Hz. Also has a large amplitude range, from several mV to a fewhundred V. This brought difficulties in the design of the railway signal detection system. At themeantime, signal-monitoring environment is very complex, which also require a goodpracticality and portability of the equipment. According to the problems mentioned above. Thesystem uses optical relays and programmable amplifier designed stalls switching circuit, tomake the amplitude range of railway signal can be converted to meet the A/D sampling range ofsignal. Then designed FFIR filter based on FPGA to analysis the signal and detect the frequencyand amplitude. The results will be delivered to and displayed by SOC. In order to adapt to thecomplex environment. A memory is added to store the data. We could use USB port to read oranalysis that data whenever needed.Compared with traditional railway signal detect equipment. The proposed system usesFPGA as digital signal processors, digital filter to analyze, detect. With the advantage of FPGA,all of them can be processed concurrently. As a result, the speed can be highly improved. Andwe designed a two-channel, both channels can work at the same time. This system uses a rechargeable lithium battery power supply. The power will be cut off automatically when thesystem is in sleep mode to save power. In addition, the system’s data storage capabilities and aPC application also greatly improved the practicality of the system.