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为了解决脉冲相位法(PPT,Pulse Phase Thermography)在处理红外检测数据时频率分辨率不够的问题,提出了一种新型的频域变换方法.利用快速傅里叶变换(FFT,FastFourier Transform)选择出包含特征频率的窄频带,对其进行线性调频Z变换(CZT,Chirp ZTransform),得到细化的频率结构.并将逐点像素分析后的结果重构出清晰的幅值和相位图像序列.在不增加采样时间的前提下获得了比PPT更高的频率分辨率.通过对铝制材料试件检测信号的对比分析,结果表明该算法可以对选频带进行有效细化,得到更精确的特征频率,有效降低了频谱泄露造成的误差.
In order to solve the problem that the pulse phase measurement (PPT) is not enough to deal with the infrared detection data, a new frequency domain transform method is proposed, which is selected by Fast Fourier Transform (FFT) (CZT, Chirp ZTransform) to obtain a refined frequency structure, and reconstructs a clear sequence of amplitude and phase images from the pixel-by-pixel analysis. The higher frequency resolution than the PPT was obtained without increasing the sampling time.Comparing the detection signals of the aluminum material specimens, the results show that the algorithm can effectively refine the selective frequency band and obtain the more accurate eigenfrequency , Effectively reducing the error caused by spectrum leakage.