ZFFT与Chirp-Z变换细化选带的频谱分析对比

在细化选带频谱分析中，复调制细化方法（ZFFT）和线性调频Z变换方法（Chirp—Z变换）是常用的两种方法。通过理论分析和仿真计算，对两者在算法、特点和误差方面进行对比分析表明：对于单频率和谱线干涉不严重的多频率谐波成分，使用FFT后进行校正，或者使用CZT细化分析，均能得到高精度的频率、幅值和相位，不必使用ZFFT；对于发生严重干涉现象的密集多频率谐波成分，ZFFT通过增大细化倍数后重采样，把干涉的各频率成分分离后进行校正可获得高精度的信号参数，但CZT只是把细化分析频带局部放大，无法消除干涉影响，提高频率分辨率也无法分离出信号的真实频率成分。通过增大采样点数，减少干涉产生的误差，CZT可以获得较高精度的信号参数，但却大大增加了运算时间。

Spectrum Analysis Comparison Between ZFFT and Chirp-Z Transform

Multiple Modulation Zoom Spectrum Analysis(ZFFT) and the Chirp-Z Transform(CZT) are widely used methods in the zoom spectrum analysis.A specific comparison of algorithm,characteristics and error analysis between ZFFT and CZT is presented here by theoretical analysis and simulation.Simulation results indicate that both FFT with spectrum rectification and CZT can accurately measure the parameters of the single component signal or the harmonic signal with multi-frequency components not heavily overlapped,and ZFFT is not necessary;for the harmonic signal with intensive multi-frequency components heavily overlapped,ZFFT can separate different component by resampling with greater Zoom multiple and rectifying spectrum,therefore the accurate frequencies,amplitudes and phases of the harmonic signal can be obtained.However CZT only partly zooms the spectrum,which can not eliminate the error caused by interference,so it is not able to obtain the accurate signal frequency components even by improving frequency resolution;by increasing sampling points,CZT can depress the error caused by interference and acquire the accurate signal parameters,but it is time-consuming.