目标信号效应对旁瓣对消系统性能的影响

讨论了理想情况下的旁瓣对消系统,分析了目标信号效应对旁瓣对消系统性能的影响,推导出了考虑目标信号效应时的权值和对消比的表达式,并以只有一个辅助通道的旁瓣对消系统为例,推导得到：目标信号对旁瓣对消系统性能的影响程度主要取决于辅助通道收到的目标信号强度,目标信号越强,目标信号效应的影响越明显。最后通过计算机仿真验证了理论分析的正确性。     

相关干扰对旁瓣对消系统性能的影响

分析了相关干扰对旁瓣对消系统性能的影响,推导出了相关干扰下的单辅助通道的旁瓣对消系统的对消比的表达式.分析表明:相关干扰可以使旁瓣对消系统的性能退化,其退化的程度正比于相关干扰的功率和目标信号的功率.最后通过计算机仿真验证了理论分析的正确性.     

宽带开环旁瓣对消技术

旁瓣对消是抗有源积极干扰的一种重要方式。文中介绍开环旁瓣对消的原理,分析了2个辅助天线系统的对消性能。针对带宽对对消性能的影响问题,提出对辅助通道信号采用延迟的方法来提高宽带系统的对消性能。仿真结果表明,只要延迟时间选择合理,这种方法是行之有效的。     

基于FPGA和DSP的自适应旁瓣对消的工程实现

详细介绍了旁瓣对消技术的工程实现方法。通过试验,对比了权系数浮点运算精度对旁瓣对消性能的影响,结果表明在辅助通道较多时用双精度浮点计算权系数进行对消可以获得较好的对消比。本文介绍的旁瓣对消模块现已应用于某雷达,在实际工作中满足雷达系统抗干扰性能指标的要求。     

自适应旁瓣对消在雷达中的应用

自适应旁瓣对消(ASLC)是雷达抗有源干扰的有效方法.它采用空间滤波技术,通过辅助接收通道在干扰方向形成波束图的零点,实现对干扰信号的抑制.本文介绍了自适应旁瓣对消的原理,然后给出了基于DSP的ASLC实现方案,分析了自适应旁瓣对消的性能.同传统的对消系统相比,该系统具有更好的抗干扰性能.     

相关性对旁瓣对消效果的影响

介绍了自适应旁瓣对消的基本原理,分析了相关系数对旁瓣对消系统性能的影响,并通过Matlab进行了计算机仿真,直观形象地验证了相关系数对旁瓣对消系统性能的影响效果.分析表明.信号相关系数的提高,可以使旁瓣对消系统的性能退化,减弱其对消效果.     

二维相控阵的自适应—自适应旁瓣对消策略

传统旁瓣对消方法采用单元天线作为辅助通道,系统对消输出的信噪比较低,且合成阵列存在较高的副瓣抬升隐患。针对二维稀疏阵列的应用特点,提出一种新的自适应—自适应旁瓣对消策略。该方法取代了传统方法中使用的单元天线以及数字加权方法,使用小型阵列作为辅助通道和射频加权,并借助辅助通道对干扰方向进行估计,根据估计得到的干扰方向信息对辅助子阵列内部的射频加权系数进行调整,使得辅助通道的波束最大可能地对准干扰方向。最后利用恒增益对消技术,实现主阵列中的旁瓣对消。仿真实验结果表明了该方法的有效性和优势。     

自适应旁瓣对消技术研究

自适应旁瓣对消是雷达抗有源干扰的有效方法,它采用空间滤波技术,通过辅助通道在干扰源方向形成波束图的零点来抑制干扰信号。本文介绍了自适应旁瓣对消的基本原理。     

利用极化滤波消除旁瓣对消器中目标效应

为了消除旁瓣对消器中目标效应的影响,文中提出了辅助天线自适应极化滤波抑制目标信号的方法。辅助天线采用正交双极化通道接收,调整接收天线极化矢量与目标信号极化矢量正交,在极化域滤除进入辅助天线的目标信号,以提高辅助天线的干信比,从而提高旁瓣对消器的对消性能。仿真实验结果验证该方法的有效性。     

存在幅相误差的ASLC系统性能分析

为了分析存在幅相误差的自适应旁瓣对消系统(ASLC)性能,推导了主辅通道存在幅度不一致性、相位不一致性以及同时存在幅相误差时ASLC系统任意通道间的相关系数公式,以干扰对消比为依据,给出了上述条件下的计算机仿真结果,得出了相应的结论.理论分析和仿真结果表明幅相误差对自适应旁瓣对消系统具有重要的影响,必须加以克服.     

Effects of desired signal on the performance of a sidelobecanceller

The performance of a sidelobe canceller is studied in a communication system where the desired signal is continually present and its amplitude in the auxiliary antennas may be large (above thermal noise). In such a system to avoid the cancellation of the desired signal, one can use a reference signal and adjust the auxiliary antenna weights to minimize the error between the reference signal and the sidelobe canceller output or one can use a steering vector. It is shown that in spite of the reference signal or a steering vector, the presence of the desired signal in the auxiliary antennas degrades the interference suppression provided by a sidelobe canceller. The amount of degradation depends on the number of degrees of freedom, the strength of the various signals, and the angular resolution of the auxiliary antenna array. Signal scenarios involving a single interfering signal as well as those involving multiple interfering signals are considered     

一种零陷展宽稳健旁瓣相消算法

受到实际条件的限制,自适应旁瓣相消器通常不可能频繁地更新自适应权值,使得其在对抗空域非平稳干扰时,会出现权值失配现象,严重影响干扰抑制性能。该文从空域密集干扰产生宽零陷的角度出发,提出一种适用于自适应旁瓣相消器的零陷展宽算法。该算法通过对主通道的合成权值和辅助天线间的协方差矩阵同时进行锥削实现零陷展宽,锥削向量和锥削矩阵只与阵元位置和展宽宽度有关,可以离线计算,在线直接调用,实现简单,适合工程实际使用。仿真实验证明,该文方法可以有效展宽自适应零陷,增强自适应旁瓣相消器对抗空域非平稳干扰时的稳健性。     

Adaptive sidelobe cancellation of wide-band multipath interference

The steady-state performance of a narrow-band sidelobe canceller using a single auxiliary element with tapped delay line is analyzed for a simple two-path interference model, and an impulse response model is developed to provide insight as to the cancellation performance that might be expected. Computer solutions are then presented for various combinations of signal and multipath parameters. It is shown that auxiliary delay taps are required for effective cancellation of wide-band multipath interference, even for fractional bandwidth-delay products. Good cancellation is generally achieved provided that 1) the delay line taps are spaced much closer than the Nyquist sampling rate, and 2) the total length of the delay line considerably exceeds the longest multipath delay, depending on multipath component strengths.     

Sidelobe level performance of adaptive sidelobe canceller arrayswith element reuse

The performance of adaptive sidelobe canceller (SLC) arrays that use the same elements for the main channel and auxiliary signals is studied. The SLC with element reuse is different from the conventional SLC because the thermal noise components of the main channel and auxiliary signals may be correlated. The noise correlation may cause serious sidelobe-level (SLL) degradation when the number of degrees of freedom exceeds the number necessary to cancel the jammers present. It is shown how his degradation can be eliminated by forming each auxiliary from subarrays rather than single elements so that an orthogonality condition is satisfied. It is shown that good cancellation and SLL performance can be obtained by using small subarrays with directive auxiliary patterns satisfying the orthogonality condition     

Interference Cancellation System for Satellite Communication Earth Station

A new interference cancellation system was devised to suppress the mutual interference between satellite and terrestrial communication systems and to expand the number of potential earth station locations for effective frequency reuse. This system basically adopts the sidelobe canceller concept and has main and auxiliary antennas. The originality of this system lies in that the auxiliary channel signal to be combined with the main channel signal is modulated by a low frequency signal, and the amplitude and phase controlling voltages are obtained by means of envelope detection, to get the envelope of the residue, and then by phase detection, using the envelope signal and the low frequency signal. As a result of experiments, more than 40 dB cancellation was achieved over a 50 MHz range for CW, FM(TP, TV) and PSK signals, even if the desired and interference signals are in the cochannel. In the field test on a 45 km path, sufficient cancellation performance and response were obtained even during fading periods.     

宽带干扰自适应旁瓣相消的方法研究

依据自适应旁瓣相消原理,着重分析了宽带干扰信号对旁瓣相消性能的影响,针对宽带干扰影响下,主辅天线间的波程差、主辅天线通道频率特性的不一致性以及主天线旁瓣的频率敏感特性等引起的自适应旁瓣相消系统的主辅天线2通道信号的去相关作用,采用了主天线通道均衡和子带自适应相消2种方法改善带宽特性,并通过MATLAB仿真验证,仿真结果表明该两种方法均可明显改善系统的相消性能,达到良好效果。