应用背景他的主要特点为从噪声中将所需要的周期信号的特征以功率谱的形式表征出来，通过设置合适的阈值可以代表目标。调频信号则是典型的脉冲压缩信号，其扩频特性使得其不易受噪声干扰关键技术%% test the compressing characters of the chirp%% TestChirpCompression周期图法的优点是能应用离散傅里叶变换的快速算法来进行估值。对利用式(1)、(2)得到的功率谱估值进行傅里叶反变换，可以得到信号的自相关函数估值。这种方法适用于长信号序列的情况，在有足够的序列长度时，应用改进的周期图法，可以得到较好的功率谱估值，因而应用很广。
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