利用相函数的频谱分析求其自功率谱，可以反映它的频率结构。
Using frequency spectrum analysis of phase function to calculate its auto power spectrum can reflect its frequency structure.
方法本组89例，应用高频率的彩色多谱勒超声检查肿大淋巴结的形态及内部回声、纵横比（L/T）、彩色多谱勒血流显像（CD FI）及阻力指数（RI）的频谱特征。
Methods The manifestation, internal echo, the L/T ratio, CDFI and RI frequency spectrum feature of the superficial lymph nodes were studied with high frequency and color Doppler ultrasound 89 cases.
首先对原始地震信号进行频谱分析，然后按其幅度谱对频率参数进行非均匀离散化。
Firstly, seismic signal is spectrum analyzed. After that, when the over-complete dictionary of atoms is being created, the selection of the frequency parameters refers to the spectrum analysis.
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