低信噪比下基于Chirp信号的频率特性测试方法  

A Measurement Method of Frequency Response Characteristics Test Based on Chirp Signal at Low SNR

作　　者：魏列江[1] 李旭方[1] 王霖[1] 董万玉 孟犁 

机构地区：[1]兰州理工大学能源与动力工程学院,甘肃兰州730050 [2]甘肃省计量研究院,甘肃兰州730060

出　　处：《计量学报》2014年第3期272-275,共4页Acta Metrologica Sinica

基　　金：基金项目：国家自然科学基金（51365208）;863计划项目（2012AA052903）

摘　　要：提出采用带通滤波和小波包变换对响应信号进行预处理，再由FFT分析和处理获得系统频率特性曲线的方法，较好地解决了低信噪比下的系统频率特性测试问题，并降低了测试时对采集系统的硬件要求。实验结果表明：对于截止频率以下的频段，在信噪比较低甚至为-20dB时，可以得到精度不低于1dB的幅频特性曲线和不低于3°的相频特性曲线，完全满足系统性能评价和控制器设计的应用要求。A method using band-pass filter and wavelet packet transform to pre-treat signal and then using FFT analysis and treatment to get frequency response diagrams is described. This method is better to solve the problems that frequency characteristic test of the system is under low SNR, and reduce hardware requirements of acquisition system in the test. The research show that when SNR is very low and even negative 20 dB value, the amplitude-frequency characteristic that accuracy is not less than ldB and phase frequency response curve that accuracy is not less than 3°can be obtained for frequency bands that is below the cutoff frequency, which fully meet the system performance evaluation and controller design application requirements.

关 键 词：计量学 频率特性 小波包变换 FFT 

分 类 号：TB973[一般工业技术—计量学]