判定真实谱峰位置的一个通用准则
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摘要
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.
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.
引文
1黄涛．准周期信号处理方法及其工程应用：［学位论文］．北京：清华大学精密仪器系，19882王飞，姜兴渭，董彩凤．周期性信号测量中的相位误差分析．数据采集与处理，1992，7（3）：171～1763刘渝．正弦波频率快速估计方法．数据采集与处理，1998，13（1）：8～114黄迪山．FFT相位误差分析及实用修正方法．振动工程学报，1994，7（2）：183～1895谢明，丁康．频谱分析校正方法．振动工程学报，1994，7（2）：172～1796陈奎孚，焦群英，高小榕．谱峰法的窗函数选择．中国农业大学学报，1997，2（4）：21～277陈奎孚，高小榕，焦群英．连续富立叶变换快速计算的移频法．地震工程与工程振动，1998，18（1）：56～618谢明，丁康，莫克斌．频谱校正时谱线干涉的影响及判定方法．振动工程学报，1998，11（1）：52～579陈奎孚，焦群英，高小榕．改善FFT精度的2种算法比较．中国农业大学学报，1996，1（6）：74～79第一作者简介陈奎孚男，博士生，1969年12月生。发表过“连续傅立叶变换快速计算的移频法”（《地震工程与工程振动》，1998年第1期）等论文。
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