关于特性检测的循环相关算法，基于am加噪声的情形-About characteristics of the cyclic correlation detection algorithm, based on the circumstances am add noise

提取淹没在噪声中的周期信号要求自相关（以判断周期）和互相关（以恢复信号自身）-Extraction drowned in the noise requirements of a periodic signal autocorrelation (to determine the cycle) and cross-correlation (to restore the signal itself)