代表的なディジタル伝送方式のタイミングジッタはSS，SN，NNの3成分から成る.タイミング再生回路は2乗素子，プリフィルタおよびPLLの縦続構成とし，プリフィルタに2次バタワース形帯域フィルタを適用して3成分のPLL帯域幅依存性を数値計算したところ，前論文［3】に比較してSS成分は大幅に減少し・PLL帯域幅の3乗に比例した.SNおよび醐成分はPLL帯域幅に比例した．これらの根拠をジッタスベクトル特性および抽出器（プリフィルタおよびPLL）のスペクトル特性の点から明らかにした．%Timing jitter in digital transmission systems has three components of SS, SN, and NN. The timing circuit is assumed to consist of a square-law device, a prefilter and a PLL arranged in tandem. The prefilter is assumed to be second-order Butterworth BPF here. The dependency of each component on PLL bandwidth has been calculated. The variance of SS component decreases considerably as compared with one in the previous work [3] and is proportional to the cube of PLL bandwidth. The variance of SN and NN components are proportional to the PLL bandwidth. The mechanism of this phenomenon is clarified in terms of jitter spectral characteristics and extractor (a prefilter and a PLL) spectral characteristics.
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