Research of Frequency-shift Track Circuit Parameter Measurement Instrument
Xue Peng Dong · Harbin Ligong Daxue xuebao · 2003
Considering the problem resulted from measuring track circuit parameter using the method of open or short need time, which affect the normal order of trains running, according to phase -locked loop digital demodulation principle and frequency selection technique, a measuring instrument controlled by the single chip microcomputer AT89C52 to on-line measure track circuit parameter was designed. Phase -locked loop CD4046 was used to demodulate low frequency modulation message; and the frequency selection technique was applied to realize the separation of frequency-shift and industrial frequency signal as well as their harmonic wave disturbance signal. Test and application prove that the measurement instrument has low cost, high precision, and stable and reliable performance.