多分量LFM干扰及动态环境下DBOC信号的捕获

Acquisition of DBOC Signals in a Multicomponent LFM Interference and Dynamic Environment

  • 摘要: 针对双二进制偏移载波(double binary offset carrier, DBOC)信号在多分量线性调频(linear frequency modulation, LFM)干扰和动态环境下捕获算法缺乏的问题,提出布莱克曼窗预处理结合分数阶傅里叶变换(fractional Fourier transform, FRFT)的干扰抑制算法以及离散多项式相位变换(discrete polynomial-phase transform, DPT)、部分匹配滤波器(partial matching filter, PMF)结合快速傅里叶变换(fast Fourier transform, FFT)加频谱校正的捕获算法。该算法首先对接收信号做布莱克曼窗预处理,抑制干扰谱线输出旁瓣,提高干扰汇聚的精确性;然后利用分级算法快速搜索信号的最优阶数,在保证精度量级的条件下减少了运算量;最后,在对应的最优阶数下做FRFT,结合干扰判断和轮询算法,逐个完成多分量LFM干扰的抑制。对干扰抑制后的信号首先利用定阶算法确定其动态阶数;然后通过DPT对动态信号做降阶处理,去除动态项;最后利用PMF-FFT加频谱校正完成DBOC信号的捕获。仿真结果表明,所提算法能够准确并完全地对三个LFM干扰分量进行逐个抑制,且抑制后的干扰分量不会对其他干扰分量的抑制造成影响。在检测概率达到1时,经过布莱克曼窗预处理后算法的信噪比比经过汉明窗预处理和经过凯塞窗预处理后算法的信噪比分别提升了4 dB和6.4 dB,比未经过预处理算法的信噪比提升了7.2 dB。此外,使用频谱校正可以突出捕获峰值,提高捕获精度。与未经频谱校正算法相比,经过频谱校正后算法的信噪比提升了1.6 dB,且能减少一定的捕获时间。

     

    Abstract: ‍ ‍To address the challenge of the lack of acquisition algorithms for dual binary offset carrier (DBOC) signals in multicomponent linear frequency modulation (LFM) interference and dynamic environment, this study proposes an interference suppression algorithm using blackman window preprocessing combined with fractional Fourier transform (FRFT) and a capture algorithm using discrete polynomial phase transform (DPT), partial matching filter (PMF) combined with fast Fourier transform (FFT), and spectral correction. First, this algorithm performs blackman window preprocessing on the received signal to suppress the output sidelobes of interference spectral lines and improve the accuracy of interference convergence. Subsequently, a hierarchical algorithm is used to quickly search for the optimal order of the signal, reducing computational complexity while ensuring accuracy. Finally, FRFT is performed at the corresponding optimal order, combined with interference judgment and polling algorithm, to suppress multicomponent LFM interference one at a time. The dynamic order of the signal after interference suppression is first determined using a fixed-order algorithm. Thereafter, the dynamic signal is reduced in order through DPT to remove the dynamic term. Finally, the PMF-FFT and spectral correction are used to capture the DBOC signal. The simulation results showed that the proposed algorithm can accurately and completely suppress three LFM interference components one at a time, and the suppressed interference components cannot affect the suppression of other interference components. When the detection probability reaches 1, the signal-to-noise ratio of the algorithm after blackman window preprocessing increased by 4 and 6.4 dB compared with the algorithm after hamming window and Kaiser window preprocessing, respectively, and by 7.2 dB compared with the algorithm without preprocessing. In addition, the use of spectrum correction highlights the capture peak and improves capture accuracy. Compared with the algorithm without spectral correction, the signal-to-noise ratio of the algorithm after spectral correction increases by 1.6 dB and reduces a certain amount of capture time.

     

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