摘要
在综合分析三种离散频谱相位差校正方法特点的基础上 ,通过仿真研究 ,得出在无噪声和小噪声情况下 ,第一种相位差法 (连续采两段信号分别作相同点数FFT)优于第二种相位差法 (采一段信号分别作N点和前面N/ 2点FFT)和第三种相位差法 (采一段信号 ,再构造新序列 :将原时域序列前N/ 2点平移N/ 4点 ,将序列的前后N/ 4点置零 ,分别对原序列和新序列进行FFT分析 ,利用对应峰值谱线的相位差进行频谱校正的通用方法 )。在大噪声情况下 ,第三种相位差法的校正精度高于其它两种方法。对于相隔较近的频率成分 (不小于 4个频率分辨率 ) ,第一种和第三种相位差法均高于第二种方法。在小噪声的实际工程中 ,推荐使用第一种相位差法加Hanning窗进行校正 ,幅值误差小于 1% ,频率误差小于0 .0 2个频率分辨率 ,相位误差小于 5度。
WT5BZ]On the basis of synthetically analyzing the characteristics of three kinds of Phase Difference Correcting Methods for calibration or discrete spectrum,simulation study indicates:when there is no noise or noise is small the precision of the first Phase Difference Correcting Method(performing FFT analysis on two original sequenceso continuously sampled) is higher than that of the second method (performing FFT analysis on the original sequence and the former N/2 point) and the third method (constructing a new sequence by shifting the former N/2 points of original time_domain sequence by N/4 points,setting both the former and latter N/4 points to zero and performing FFT analysis on the original sequence and new one,the spectrum can be corrected by taking advantage of the phase difference of two corresponding peak spectral lines).Under the condition of big noise,the precision of the third Phase Difference Correction is higher than others'.As to the signals which involves closely spaced frequency components (not less than 4 resolutions),the precision of the first and third Phase Difference Correcting Methods is higher than that of the second,In engineering application,it is recommended to correct the spectrum containing small noise by the first Phase Difference Correcting Method with Hanning window.The errors of amplitude,frequency and phase are under 1%,0.011 resolution and 5 degree respectively. [WT5HZ]
出处
《振动与冲击》
EI
CSCD
北大核心
2001年第2期52-55,共4页
Journal of Vibration and Shock
基金
国家自然科学基金资助项目 编号 :50075049
国家教育部高等学校骨干教师资助计划项目 编号 :教技司 [2000 ] 65号
