Research And Implementation On Track Frequency-shift Keying Signal Intelligent Unit

ZPW-2000track circuit has become the mainstream of china railway system, and that thetrack frequency-shift keying signal work well has a big significance for traffic safety.Therefore it needs to detect parameters relative to the track frequency-shift keying signal inreal-time, and uses the test results in realizing Closed-loop code and control of code modulein the fully electronic execution unit to improve reliability of code module. On the other hand,to bring parameters about the track frequency-shift keying signal into the computermonitoring system and monitor those parameters in real-time monitoring not only can reducethe probability of accidents, but also easy maintenance. This paper proposed a hardware andsoftware design solutions, based on the analysis of track circuit and the characteristics of trackfrequency-shift keying signal, against to the high resolution and real-time required bydetection of frequency-shift keying signal.The main function of the track frequency-shift keying signal intelligence unit is todetective its carrier frequency and low frequency. Taking into account the timeliness of thewhole system, it chooses a high-performance, low-power, floating-point DSP devices-TMS320F2828335as core processor which is used to realize collection and operation oftrack frequency shift signal. It obtains the time-domain characteristics and frequency-domaincharacteristics of track frequency shift signal by using Matlab to analyze its mathematicalmodel. By comparison, the frequency-domain characteristics can be used to calculate thecarrier frequency and low-frequency spectrum analysis, so spectrum analysis method isadopted. In the algorithm, because of the irreconcilable contradictions between FFT frequencyresolution and speed of operation, it uses under-sampling techniques to reduce the samplingfrequency. Meanwhile, the sampling ratio correction method and the energy center frequencymethod correct the initially obtained frequency to reducing detection errors. Algorithmobtained by modifying TI floating-point arithmetic functions has a short running time andhigh efficiency features. After verification of the physical test, the results show that detectionaccuracy of track frequency-shift signal intelligence unit meets the design requirements. Adual DSP processor TMS320F28335is used as hardware core to complete collecting andparallel computing. The system outputs results after compassion DSP bus with SPI bus, whichenhances the reliability of system. It can realize closed-loop code and control of station code,collect and monitor track frequency shift signal in real-time of computer monitoring system.Track frequency-shift signal intelligence unit is a key part of the whole computer codeexecution units of interlocking modules. Code module accepts commands from interlockdevice via CAN bus, and control code device to send the modulated low-frequency and carrierfrequency to track surface. Track frequency-shift signal intelligence detection unit in code modules receives amplifying signals, identifies low frequency and carrier frequency signal,and compares them with interlocking information received. If the result is same, sending codeis successfully; if not, code module stops sending code and output alarming information.Alarm information is sent to the maintenance terminal via the CAN bus, forming a closedloop hair codes. At the same time, the carrier frequency and low-frequency information is sentto the computer monitoring system via the CAN bus. The computer monitoring systemmonitors and records the carrier frequency and low-frequency in real-time, and forms a log toeasy to find the problems. Thus code equipment failure frequency will be reduced while thesafety of train operation will be greatly improved; at the same time, it can facilitate the workof equipment maintenance staff to improve their work efficiency.