判定真实谱峰位置的一个通用准则

A General Rule to Determine Real Spectrum Peak Position

提出了许多改善ＦＦＴ离散谱估计精度的方法，但必需知道谱峰的大体范围。作者证明了对称窗函数的频谱主瓣内的两条ＦＦＴ谱线为最大和次大。根据这一性质，对多频率信号，可按照ＦＦＴ谱线局部极大的原则确定真实谱峰位置，这是非常简便且易于编程的准则。仿真结果表明，如果两个真实谱峰相距不少于三条谱线，上述准则是正确的；随着谱峰接近，则可能存在误判，并且加汉宁窗错误率低于矩形窗。

A lot of methods to improve FFT discrete spectrum line estimation have been proposed,most of which require a priori approximate position information of real spectrum peak. It is deduced in the paper that the 2 FFT discrete spectrum lines in the main lobe of the special spectrum character of symetric window are maximum and submaximum perspectively. According to this character, the real peak appoximate positions could be determined for the multifrequency signal, by the rule of maximum at local frequency band,which is very simple and easy to be programmed.The simulation results show that if there are more than 3 discrete spectrum lines between 2 real peaks,the rule is correct. As the real peaks draw close,misjudgment takes place,and the misjudgment rate in the case of rectangular window is more serious than that in hanning window.