计算FFT计算信号频率时 分辨率 f=fs/N ，嵌入式中由于存储空间有限 导致分辨率f不能提高 ，该算法使信号分辨率大大提高-FFT calculation when the signal frequency resolution f = fs/N, embedded in the resolution f not improve due to limited storage space, the algorithm makes the signal resolution is greatly