Research On Adaptive Technology Applied In Railway Signal Demodulation

Adaptive signal processing is widely applied in the communication system, radar and biomedicine engineering, However it has not been involved in the railway signal detection system. This paper focus on researching adaptive filtering technology applied in railway signal demodulation, introducing the theory of adaptive filtering, analyzing its characteristic and main factors that affect its capability. Based on LMS algorithm, which is classic for adaptive technology, a discussion is given on how it could be adopted in the demodulation for several modes of railway signal, according to MSE curve, tracing ability and maladjustment.In the second half of the paper, two main modes of railway signal—A.V. counting and domestic YP signal, combined with possible noise from practical railway, is processed by LMS adaptive filter, to eliminate interference and to be demodulated separately. Base on that, a demodulation scheme is proposed.The result indicates adaptive filter could eliminate interference perfectly when the factor is properly set, and have a good tracing ability without knowing statistic characteristics. For A.V counting signal, the demodulated result meet the requirement with high accuracy, for domestic YP signal, the demodulated result arrives at the class-2 standard, and could get the upper and lower side frequency. The demodulation scheme is a good implementation for the traditional demodulation method and therefore has practical value.