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FSK信号作为保障铁路安全运行的主要信号制式 ,在国内铁路上现在有两种 ,是法国引进的 UT信号和国内自主开发的 YP信号。小波变换是继傅里叶变换之后的重大突破 ,而小波包则是小波变换的进一步发展 ,克服了小波变换的一些不足。本文首先研究了车载 FSK信号的特征 ,再利用小波包对车载 FSK信号进行滤波处理。文中 ,给出了如何确定给定频率的信号在小波包分解树各个分解层中对应节点的算法 ,在滤波处理过程中 ,为了处理带内的噪声 ,也给出了采用阈值的方法来减少带内白噪声 ,阈值的选取充分应用到 FSK信号的小波包分解的特点。最后 ,我们给出了计算机产生的仿真 FSK信号和现场采集的 FSK信号的两种仿真 ,仿真结果表明 ,根据车载 FSK信号的特性 ,小波包方法是处理车载 FSK信号的有效方法。
FSK signal as the main signal to protect the safe operation of the railway signal system, there are now two types of railway in China, is the introduction of France UT signal and the domestic self-developed YP signal. Wavelet transform is a major breakthrough after Fourier transform, and wavelet packet is the further development of wavelet transform, to overcome some shortcomings of wavelet transform. This paper first studies the characteristics of the vehicle-mounted FSK signal, and then uses the wavelet packet to filter the vehicle-mounted FSK signal. In this paper, how to determine the signal of a given frequency in the wavelet packet decomposition tree corresponding decomposition algorithm in each node, in the filtering process, in order to deal with the band noise, but also gives the threshold method is used to reduce the band Internal white noise, threshold selection fully applied to the FSK signal wavelet packet decomposition characteristics. Finally, we give two simulations of computer generated FSK signal and FSK signal collected on site. The simulation results show that the wavelet packet method is an effective method to process the FSK signal based on the characteristics of vehicle FSK signal.