对流层散射信道传递时间信号的抖动抑制模型

对流层散射信道传递时间同步信号过程中,信道的多径效应及噪声会引起信号抖动。为抑制抖动、提高时间同步精度,引入经验模态分解和小波阈值组合的抖动抑制模型。组合抖动抑制模型中,首先根据经验模态分解原理对原始信号进行分解,然后利用小波阈值对分解得到的各分量进行处理,最终利用处理结果重构信号。为提高组合模型的抖动抑制效果和原始信号的保持能力,利用连续性好、柔和度高的阈值函数对小波阈值中的传统阈值函数进行改进。利用实测数据验证模型的结果表明,在抖动抑制和信号保留方面,组合模型较单一模型以及常用的Kalman模型优势明显。

Jitter mitigation model for time signal transferred via troposcatter

During troposcatter transfers the time synchronization signal, multipath and noises of the channel can contribute jitter to time synchronization signal. In order to mitigate this jitter, the empirical mode decomposition (EMD) combined with wavelet model is proposed. In the combined model, EMD is used to decompose the data into several intrinsic mode functions (IMFs) and a remainder term. And all IMFs are de-noised by wavelet threshold, which is already improved by the better coherent and gentler threshold function. The final signal is reconstructed with these processed IMFs and the remainder term. Experimental data are used to demonstrate this combined model. Compared with the simplex model and the Kalman model, combined model has advantage on effect of de-noising as well as authenticity.