SSA+FBPF方法及其在北斗卫星钟差周期项提取中的应用

The SSA+FBPF Method and Its Application on Extracting the Periodic Term from BeiDou Satellite Clock Bais

针对奇异谱分析(singular spectrum analysis,SSA)方法在重建准周期项时容易存在频率混叠的现象,傅里叶带通滤波器(fourier band pass filtering,FBPF)提取准周期项时,边界值极易受到残留的趋势项的影响而导致其不够精确,本文提出了一种SSA与FBPF相结合的方法(SSA+FBPF),即先利用SSA方法对信号进行分层选组重建,再对重建信号进行傅里叶带通滤波。仿真试验结果表明在信噪比(SNR)为0.017的情况下,SSA+FBPF方法重建周期信号精度比SSA方法提高了35%,比FBPF方法提高了26%,这说明该方法不仅抑制趋势项对边界值的影响,而且具有良好抗噪声干扰的能力。将SSA+FBPF方法用于重建北斗卫星PC06和PC07的24h周期项,发现北斗卫星钟PC06和PC07周期项幅值均存在明显变化。

The frequency aliasing often exists when reconstructing the periodic signals using the singular spectrum analysis(SSA)method,the precision of the boundary value extracting by Fourier band-pass filtering(FBPF)is often not precise enough because of the influence of the residual trend term.In view of these kinds of situation,a combined method that joints SSA and Fourier band-pass filter method(SSA+FBPF)is proposed,the signal reconstructed by SSA is filtered by Fourier band-pass filter after SSA.The simulation results show that the reconstruction precision using SSA+FBPF method can improve 35%and 26%relative to that using the SSA and FBPF methods,respectively,in the case SNR is 0.017.These demonstrate that the SSA+FBPF method can reduce greatly the edge effect and has good robustness.The amplitudes of the 24 hterms obtained by the SSA+FBPF method from the BeiDou satellite clock PC06 and PC07show that they have significantly variation.