微动目标AM-FM信号调幅指数估计方法

Amplitude modulation index estimation of AM-FM signal scattered from micro-motion target

为分析雷达目标微动特征,提出了一种高精度调幅-调频(AM-FM)信号调幅指数估计方法。将微动目标的雷达回波表示为调制频率相等的正弦调幅-正弦调频信号模型,分析了传统调幅指数估计方法处理含有正弦调频特征信号存在的不足,仿真了调频指数对调幅指数估计产生的影响。利用Teager非线性能量算子,将幅度调制信息有效地从AM-FM信号中分离出来。利用FFT技术对回波信号的包络进行谱分析,提取调幅指数。通过与传统的调幅信号调制指数估计方法进行比较,说明该方法提高了调幅指数的估计精度。

To investigate the micro-motion characteristics of aircraft, a high precision estimation method of amplitude modulation index is developed. First, the echo of micro-motion target is described as an AM-FM signal model in which the frequency of AM is equal to that of FM. Secondly, the deficiencies of traditional methods to estimate AM index are analyzed. The effects on AM index result by frequency modulation are simulated. Thirdly, the Teager non-linear energy tracking operator is used to separate the amplitude from the AM-FM signal. Finally, the spectrum of echo envelope is analyzed, and the AM index is achieved by FFT. Compared with the traditional estimation technique, the proposed method has better precision.