Design Of Railway Signal Testing Instrument Based On ARM And DSP (Part DSP)

UM71, including ZPW-2000A, joint-less track circuit has been dominating China's railway It is significant for traffic safety when track circuit works correctly. The track signal interfered will lead to error action of railway signal device and then traffic accident happens. Through monitoring of railway signal and making a judgment, can help the track signal maintainer to repair the failure device and avoid accident occurringThis thesis designs one kind of railway signal test instrument based on ARM/DSP structure. The instrument can help maintainer to repair the malfunction equipment. The thesis uses floating-point DSP-TMS320VC33 as an integral part of the instrument to complete the signal demodulation, spectrum analysis and detailed treatment. As a kind of real-time signal test instrument, it takes full advantage of the floating-point DSP chip which is efficient and flexible, so the instrument is very suitable to be applied in the field. The application area of this instrument mainly covers the UM71, ZPW-2000A and 25Hz phase detecting track circuit. The function of this signal test instrument includes digital demodulation of FSK signal, section carrier wave's frequency detection, signal amplitude measurement, station signal's phase and amplitude measurement.This thesis focuses on the application of ZFFT algorithm in real-time signal analysis. ZFFT algorithm can be used to ensure the efficiency of processions and improving the resolution of the spectrum. Besides, this paper propounds a number of improvements of the algorithm and simulates all of the algorithms through MATLAB software. Theoretical analysis and experimental results show that the resolution of the modulation frequency can be reached 0 03Hz, meet the actual application requirement. This thesis also works out the DSP software design based on the algorithm; In order to improve system's effciency, DSP algorithm is edited in assembly language. In addition, the hardware structure of the instrument is designed in this thesis, mainly about the external devices of the DSP and the interface circuit between dual-port RAM CY7C028 and DSP. Based on the interface circuits between VC33 and CY7C028, this thesis designs the communication between the two chips.