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.     

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.     

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。     

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。     

雷达旁瓣对消系统攻防对抗技术研究

本文基于旁瓣对消原理对雷达旁瓣对消系统的性能和特点作了全面的分析,利用旁瓣对消系统固有的缺陷提出攻击旁瓣对消系统的方法以及具体实施方案,并提出了利用评估模型对攻击效果进行仿真的方法,证明了提出的干扰方法是有效的。     

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.     

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。     

对自适应旁瓣对消雷达的宽带干扰研究

分析了宽带干扰对旁瓣对消系统的影响,介绍了相关系数的计算方法.并给出宽带干扰下按最小均方(LMS)准则求解加权系数的计算过程,然后以天线阵对干扰的方向增益为依据,借助于Matlab给出宽带干扰的效果分析.     

对自适应旁瓣对消系统的闪烁干扰方案研究

现代雷达普遍采用旁瓣对消技术抗有源干扰,该技术大大降低了从雷达天线旁瓣进入的干扰信号功率,使得从雷达天线旁瓣进入的有害干扰信号不至于严重妨碍雷达工作。文中分析了雷达开环自适应旁瓣对消系统的工作原理,提出了采用对开环自适应旁瓣对消系统进行闪烁干扰的理论依据及实施方法,并对闪烁干扰的干扰效果进行仿真分析,结果证实了闪烁干扰的可行性,为干扰自适应旁瓣对消系统提出了可行的干扰方案。     

一种新的天线旁瓣对消抗干扰技术的实现

给出了一种新型天线旁瓣对消系统的技术实现方法，对其系统组成和对消原理进行了分析。同传统的对消系统相比，该系统具有更好的抗干扰性能。     

旁瓣对消系统的对消比上限分析

构造了一个理想的旁瓣对消系统和一个理想的信号环境,分析了旁瓣对消系统的对消比上限,推导出了对消比上限的精确表达式及近似表达式,得知对消比的上限取决于辅助通道的干噪比和辅助通道的数量.最后,给出了与理论分析相一致的仿真结果.     

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。     

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     

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.     

基于快速解扩滤波器优化的DS-CDMA多用户干扰抑制

该文提出了一种新的DS-CDMA信号检测方法,采用正交锚定的旁瓣抵消器结构和训练序列,基于最小滤波器输出能量准则,实现了解扩滤波器快速非自适应优化,并通过测定码匹配滤波器输出的信号干扰噪声比,有效控制了码匹配滤波器失配对滤波器优化的影响,从而实现了稳健的多用户联合信道干扰抑制。进一步采用RAKE技术,提高了Rayleigh衰落信道中接收机的性能。     

Robust microphone arrays using subband adaptive filters

A new adaptive beamformer which combines the idea of subband processing and the generalised sidelobe canceller structure is presented. The proposed subband beamformer has a blocking matrix that uses coefficient-constrained subband adaptive filters to limit target cancellation within an allowable range of direction of arrival. Simulations comparing the fullband and subband adaptive beamformers show that the subband beamformer has better performance than the fullband beamformer when the target and/or interfering signals are coloured. In reverberant environments, the proposed subband beamformer also performs better than its fullband counterpart     

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。