线性调频波的转发干扰对消分析

Analysis on repeater jamming active cancellation for linear frequency modulated wave

提出了一种线性调频波的转发干扰对消方法,该方法利用匹配滤波输出存在时延与频移上的强烈耦合,通过调整对消波的相位和频移,使其匹配滤波输出与原回波输出基本满足时间重合、幅值相近、相位相反的对消关系,减小回波总输出幅值,即可有效降低其被检测概率;推导了只进行调相转发的对消输出公式和同时进行调频调相转发的对消输出公式,分析了其理论输出特性,并分别对其进行了仿真验证.仿真结果表明,对消波若只进行相位调制,其对消效果与转发时延和信号带宽之积相关,此值越小则对消效果越好,但对相位调制和幅度控制的精度要求也越高;对消波若同时进行相位和频率调制,其对消效果由转发时延与信号脉宽之商直接决定,此值越小则对消效果越好,带宽不影响对消效果,但带宽越大则对消效果对频率调制精度要求越高.

A repeater jamming active cancellation method for linear frequency modulated（ LFM） wave was proposed. Utilizing the coupling between time delay and frequency shift of matched filtering output,by phase and frequency modulating,the synthetizing output of cancellation and original wave can meet the cancellation conditions on time,amplitude and phase,consequently the filtering output decreases as well as the detection probability. Formulae for the output of the phase-only modulated wave and phase and frequency modulated wave were derived. Filtering output characteristics were analyzed theoretically. Simulation results show that,for the phase-only modulated wave,the cancellation effect is proportional to the product of repeating time delay and wave bandwidth,decrease of which resulting in a better cancellation effect but a higher demand on the accuracy of phase and amplitude controlling. For the phase and frequency modulated wave,the cancellation effect is decided by the division of repeating time delay and pulse width. Bandwidth of the wave has no influence on the cancellation effect. A wider bandwidth needs a higher accuracy of the frequency modulating.