基于分数阶傅里叶变换的直扩通信快速线性调频干扰抑制

针对直接序列扩频系统中的线性调频干扰,将短时傅里叶变换和分数阶傅里叶变换相结合,提出了在短时傅里叶域进行线性调频干扰参数粗估计而在分数阶傅里叶域进行精确估计,并根据线性调频干扰在分数阶傅里叶域形成的脉冲位置和强度自适应选择消波区间达到抑制线性调频干扰的目的。仿真实验表明,所提出的干扰抑制方法在干信比JSR40情况下,对线性调频干扰有很好的抑制作用,位错误率BER性能可改善103倍。

Fast linear frequency modulation interference excision in DSSS system using fractional Fourier transform

For the suppression of linear frequency modulation interference in a direct sequence spread spectrum system,a new method is proposed based on the Short Time Fourier Transform(STFT) and the Fractional Fourier Transform(FRFT). At first, the parameters of the linear frequency modulation interference is estimated coarsely using STFT, then the fine search for correct parameters is implemented in FRFT. At last, according to the position and intensity of the pulse by linear frequency modulation interference in the Fractional Fourier domain, it is adaptive to choose the field to Sachieve the purpose of the suppression of linear frequency modulation interference. Simulation results show that the proposed method works well to suppress the linear frequency modulation interference and the performance of bit error rate (BER) can improve more than 1000 times when jammer to signal ratio(JSR)<40