Key Technology Research Of Reliability Detection Device Based On TWC System

In ATC signal system, TWC system is an unsafe communication subsystemwhich can implement data and information transmission between the train and waysideequipment. It has two types: one is on-board TWC and another is wayside TWC. Whenenvironmental temperature and electromagnetic environment change, inductance andcapacitance in the wayside FSK signal R-T unit will drift. In this case, Central Frequencyof LC resonant circuit will migration, because of this instability, FSK communicationquality will descend with influence of data transmission. At last, the train operationproblem such as train’s delay, non-stop in the station and obtrusion away from the stationwill be inevitable.The quality of signal which the train antenna receives is not only related to LCoscillator frequency, but also related to electromagnetic environment and train status. Toimprove FSK communication quality, it’s necessary to develop a kind of FSKcommunication signal tester. By this test device, we can find relations among measuredFSK signal parameter, compensation capacitance parameter and resonance frequency ofcircle communication device，and then we can build a corresponding database foranalysing. This development is important to control compensation capacitor for maintainer,it also plays a significant role in improving the telecommunication quality of FSK. In orderto meet the need of tester′s real time requirement and performance in EMI suppression, atest device based on hardware of NI company and LabVIEW software is developed. Thedevice can have real-time detection of FSK signal in TWC system，it can implement FSKsignal’s modulation, demodulation, sending and reception. This tester is made of hardware(Data Acquisition Card PXI6251and other associated equipment) and software(LabVIEW8.5) with characteristics of real-time, reliability and EMI. For receiving waveform, demodulating data and error rates, it can make real-time storage, analysis anddisplay. So, this device provides practical materials for maintaining TWC system to solvethe problem without special equipment in subway signal.About capacitance’s drift, this paper also studied on automatic compensatingloop control device of capacitance based on51series chip microcomputer system. For thedevice,51series chip microcomputers are used to be as core hardware by C languageprogramming. Its loop control can compensate automatically for drift of capacitance. Thetheory is as follows: when LC resonant circuit is in resonance, the voltage across thecapacitance is the largest, the value of capacitance will change to be smaller influenced bychanged external factors, so it is necessary to use test device for collecting the voltagesignal across the capacitance. After analyzing the signal, we can adjust capacitor rowsconnected to the capacitance, then resonant circuit capacitance is able to accomplishautomatic compensation.In this text, simulation experiments have been done by Proteussoftware, by those experiments, we find closed-loop controlled device can carry on thecompensation of capacitance change. It provides basic methods for studying capacitanceautomatic compensating of TWC system.