对流层散射信道传递时间信号的抖动抑制模型

Jitter mitigation model for time signal transferred via troposcatter

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。

During the transmission process of time synchronization signal in troposcatter channel,the multipath effect and noise of the channel can contribute jitter to time synchronization signal.In order to mitigate this jitter,the EMD(empirical mode decomposition)combined with waveletthreshold model was proposed.In the combined model,the EMD was used to decompose the original signal,the wavelet threshold was adopted to process the decomposed components and then the processed results were utilized to reconstruct the final signal.In order to improve the jitter mitigation effect and the signal authenticity of the combined model,the traditional threshold function in wavelet threshold was perfected by the better coherent and gentler threshold function.Experimental data were used to demonstrate this combined model.Compared with the simplex model and the Kalman model,the combined model has advantage in effect of de-noising as well as authenticity.