基于自适应天线的跳频系统干扰抑制方法

自适应天线与跳频技术相结合可进一步提高系统的抗干扰性能.对跳频系统中快速跟踪干扰的抑制,采用基于特征空间(ESB)自适应波束形成算法可提高波束的收敛速度,并与空间平滑技术相结合,可有效抑制与期望信号相关的快速跟踪干扰.计算机仿真结果证明了该方法的有效性.     

CSMG波束形成算法在相干和非相干环境中的应用

讨论了如何将CSMG自适应波束形成算法与空间平滑法相结合，应用到同时存在相干干扰和非相干干扰的环境中。该算法具有空间平滑法和CSMG波束形成算法的优点，能对相干干扰抑制，并且在非相干干扰方向也能形成很好的零陷，大大提高了系统的抗干扰性能。对该算法、普通CSMG算法和与空间平滑算法相结合的MVDR算法进行了计算机仿真，并对仿真结果进行了比较，证明了该算法结构的可靠性和优越性。     

相干多径环境下自适应阵列的性能改进

针对传统自适应波束形成算法无法抑制相干干扰的问题,引入了一种预处理技术--自适应加权空间平滑(Weighted Spatial Smoothing,WSS)算法,结合线性约束最小方差准则,可以有效地抑制相干干扰.同时,针对WSS引起的孔径损失,提出了一种对子阵进行相位补偿,利用全阵做波束形成的方法.理论分析和仿真结果表明,该方法对相干干扰的抑制能力明显优于常规均匀空间平滑(Uniform Spatial Smoothing,USS)算法,而且避免了孔径损失.     

适用于跳频通信系统的循环相关约束差分恒功率算法

针对跳频通信系统所使用的恒功率算法(CPA)存在的问题:收敛性较差和误捕干扰,结合跳频信号解跳后的恒功率特性和循环平稳特性,提出了一种新的循环相关约束差分恒功率算法(CCDCPA).建立了合理的阵列权矢量代价函数,详细推导了该种算法的迭代公式.仿真结果表明,CCDCPA算法不仅收敛性优于CPA算法,而且可以抑制窄带干扰和宽带干扰,是一种特别适用于跳频通信系统的盲波束形成算法.     

天线理论、天线设计、天线方向图

0016361顶线材料变更对天线电气性能的影响[刊]/戴兆之//现代通信技术.—2000,(1).—37～41(C)0016362基于自适应数字波束形成的跳颁干扰抑制研究[刊]/邱永红//通信学报.—2000,21(7).—39～44(L)本文主要研究了基于自适应数字波束形成(DBF)的卫星通信地面站跳频接收系统的抗干扰性能,提出了采用将 DBF 与跳频相结合的方式来抑制跳频快速跟踪干扰和宽带阻塞干扰,对干扰抑制性能进行了分析及仿真,其仿真结果与分析是一致的。参4卫星下行链路计算及接收天线增益的测量(见0016915)     

基于波束形成跳频系统抗干扰方法研究

本文研究利用波束形成技术与跳频技术相结合,在存在宽带阻塞干扰以及跟踪干扰时,将信号与干扰在空域进行分离,提高跳频系统的抗干扰性能。指出利用空间平滑不仅可以有效抑制相干跟踪干扰,而且提高了波束的收敛速度。仿真结果证明了该方法的有效性。     

基于波束形成跳频系统抗干扰方法研究

本文研究利用波束形成技术与跳频技术相结合，在存在宽带阻塞干扰以及跟踪干扰时，将信号与干扰在空域进行分离，提高跳频系统的抗干扰性能。指出利用空间平滑不仅可以有效抑制相干跟踪干扰，而且提高了波束的收敛速度。仿真结果证明了该方法的有效性。     

基于二维虚拟空间平滑算法的跳频通信系统跟踪式干扰抑制研究

基于均匀矩形阵列,利用阵列接收信号及其共轭信息,推导出2维的虚拟空间平滑算法。通过构造2维虚拟子阵,消除干扰信号与期望信号之间的相关性,避免了有效阵列孔径的损失,提高了算法的空间谱分辨率。将该算法与相位补偿技术相结合,给出了一种抗跟踪式干扰的跳频通信系统。通过理论分析和模拟仿真,验证了该系统对跟踪式干扰具有较好抑制能力,在干扰方向的零陷抑制深度达50 dB以上,并且与普通跳频系统相比在-3 dB的强干扰环境下具有优良的误码率特性。     

相干环境下LCMV自适应阵列抗干扰问题研究

相干干扰环境下,自适应阵列性能会急剧下降,常用的处理方法是空间平滑。然而,采用常规均匀空间平滑的自适应阵列对相干干扰的抑制能力较差,而且会损失阵列孔径。该文提出一种改进的相干干扰抑制方案:首先,提出了一种自适应的加权空间平滑(Weighted Spatial Smoothing, WSS)算法,它将各子阵的相关矩阵进行加权平均,可以最大程度地解相干;然后,在WSS基础上,利用线性约束最小方差(LCMV)准则得到子阵波束形成器最佳权矢量;最后,提出了一种利用子阵间的相位关系对全阵做波束形成的方法。该方案大大提高了阵列对抗相干干扰的能力,同时避免了一般空间平滑后阵列的孔径损失。理论分析和仿真结果说明了方法的有效性和稳健性。     

基于自适应数字波束形成的跳频干扰抑制研究

本文主要研究了基于自适应数字波束形成（ＤＢＦ）的卫星通信地面跳频接收系统的抗博物邮采用将ＤＢＦ与跳频相结合的方式来抑制跳频快速跟踪干扰和宽带阻塞干扰,对干扰抑制性能进行了分析及仿真其仿真结果与分析是一致的。     

Performance comparison of frequency-diversity and frequency-hoppingspread-spectrum systems

In the presence of partial-band Gaussian interference, the frequency-hopping spread-spectrum system, without and with optimum diversity, performs worse than the frequency-diversity spread-spectrum system proposed by Kaleh (see ibid., p.886-93, vol.44, no.7, 1996) The latter offers the advantage of coherent reception with coherent diversity combining     

Adaptive array with global weighted spatial smoothing

Global weighted spatial smoothing is utilised in adaptive arrays for coherent interference suppression. With the prior knowledge of the directions of coherent sources, signal cancellation is eliminated and the smoothing index can be reduced to the number of sources even for small spatial separation.     

A diversity scheme for a phase-coherent frequency-hoppingspread-spectrum system

Frequency diversity for a phase-coherent frequency-hopping spread-spectrum system is proposed. The frequency band of the communicator is partitioned into L disjoint subbands on which L replicas of the communicator signal are simultaneously transmitted; each signal replica hops independently in its subband. Therefore, both phase continuity and coherent optimal combining of the received replicas are possible. Optimum diversity is thus at least 6 dB better than the conventional noncoherent FH-SS system. We show that a smart jammer should be present in all subbands. We also give a sufficient condition that forces the jammer to spread its interference signal on the whole communicator frequency band     

跳频扩频系统的Matlab模拟仿真实现

跳频扩频技术采用特定的扩频函数及载波跳变来实现频谱展宽,具有很强的抗干扰性,并具有信息隐蔽、多址保密通信的特点;PSK调制方式由基带脉冲控制载波相位。在Matlab／Simulink下建立了采用BPSK方式的跳频扩频（FH—SS）通信系统模拟模型,并编程仿真实现该系统,对跳频扩频通信的实现有重要意义。     

Frequency-hopping versus interference cancellation for TD-CDMA

This work considers asynchronous time division code division multiple access (TD-CDMA) systems with RAKE receivers and one stage of parallel interference cancellation (PIC) or serial interference cancellation (SIC). A general method based on the concept of spherically symmetric signals is presented for the evaluation of the average probability of error of uncoded TD-CDMA systems. Slow frequency-hopping (SFH) with frequency overlap (FO) between adjacent carriers and interference cancellation are also included in the analysis, which considers the multipath Rayleigh fading channel (which models indoor and outdoor vehicular radio propagation). We analyze quadrature phase shift keying (QPSK) modulation with coherent demodulation and multipath (frequency) diversity with maximal ratio combining (MRC). Power control, adaptive SFH, and interference cancellation are employed for improving the bit-error rate (BER) performance. It is found that the scheme with SFH, in spite of the FO, always improves the performance substantially, and interference cancellation, in general, provides the highest BER improvement     

An orthogonalized blind algorithm for hybrid of adaptive array and equalizer

The problems generated by the interference will be more complicated in the future. A combination of adaptive array and equalizer has been employed to solve the problems of interference when an adaptive array alone cannot suppress all the interferences. A constant modules algorithm (CMA) of the combination system was proposed to solve the problems of insufficient degrees of freedom and main‐beam multipath interference when no training signal is transmitted. The limitation of the CMA for combination systems is due to its slow rate of convergence. In this paper, an orthogonalized blind algorithm for hybrid of array and equalizer (OBHAE) is proposed to combat the problems of the interference. Because the modified input vector of the adaptive array is orthogonalized by the OBHAE in advance, the convergent rate of the CMA system can be improved by the OBHAE. When the coherent interference presents, the performance of the system will be degraded. In this paper, an orthogonalized spatial smoothing blind (OSSB) algorithm is proposed to further enhance the cancellation of the coherent interference. In the OSSB, we combine the OBHAE with the spatial smoothing method to combat the coherent interference problem. Simulation results are presented to demonstrate the merits of the OBHAE and the OSSB. Copyright © 2012 John Wiley & Sons, Ltd.     

相干光学多波束形成的原理及其理论分析

相干光学多波束形成技术是根据光学的干涉与衍射原理,利用光学傅里叶变换而实现的一种新型的宽带射频多波束形成技术.扼要介绍了其工作原理,并对其建立了较为完善的物理模型,通过详细的理论推导和软件仿真,表明此结构能够形成多波束,在空域覆盖、波瓣宽度、小体积、抗电磁干扰等方面具备重要的性能优势.