The filter has no fundamental frequency decay and phase delay, and all harmonics above2nd order are filtered.

该滤波器在基频处的幅值无衰减，相位无延时，能将2次以上的谐波全部滤掉。

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Generally speaking, it is caused by the difference between the equilibrium and the frequency decay, which is difficult to be controlled.

通常认为均衡特性和频率衰减特性的差异是造成这种现象的主要原因，很难抑制。

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By analyzing the early phase of frequency decay, it is possible to identify multi-shock earthquake sequence, but it is difficult to rapidly judge intermittent double-shock and swarm.

分析地震序列前期的时频度衰减曲线有可能区分出多震型地震，但快速区分间歇双震型和震群型地震较为困难。

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