非线性调频信号的自适应时频滤波算法

针对传统的时域或频域滤波算法对非线性调频信号滤波去噪效果不好的问题，本文提出了一种时频域内非线性调频信号的自适应滤波去噪算法。首先对原信号进行广义S变换获得其时频分布，接下来利用有效信号时频分布特性选取时频通域，构造区域滤波算子并去除掉时频通域外的噪声分量的时频分布；然后利用有效信号分量的时频聚集性构造自适应时频滤波算子，对含有随机噪声的有效信号分量进行滤波处理，得到滤波去噪后的信号的时频分布；最后利用广义S逆变换将处理后的时频分布变换到时间域，得到滤波去噪后的信号。通过仿真实验的结果可知，本文提出的算法在非线性调频信号的滤波去噪和有效特性保持方面取得了较好的效果。 

Adaptive Time-Frequency Filter Method of Nonlinear Frequency Modulation Signal

In order to solve the problem that time domain or frequency domain filtering is not effective in denoising for nonlinear frequency modulation signal, a novel adaptive time-frequency (TF) filtering method based on generalized S-transform is proposed. Firstly, the TF distribution spectrum of the signal is generated by applying generalized S-transform. Then, based on the TF distribution characteristics of the effective signal component, the TF pass region of the signal is identified, outside of which, the TF distribution of the noise is removed. In the next step, an adaptive TF filter is constructed using the TF concentration of the effective signal component, to suppress the noise within the effective signal component to obtain filtered TF distribution of the nonlinear modulation signal, which is then converted to time domain using inverse generalized S transform, to generate the filtered signal. Simulation results demonstrate that the proposed algorithm provides satisfactory performance in noise suppression and improves the signal-to-noise ratio.