Noise amplitude modulation jamming signal suppression based on weighted-matching pursuit

To suppress noise amplitude modulation jamming in a single-antenna radar system, a new method based on weighted-matching pursuit （WMP） algorithm is proposed, which can achieve underdetermined blind sources separation of the jamming and the target echo from the jammed mixture in the single channel of the receiver. Firstly, the presented method utilizes a prior information about the differences between the jamming component and the radar transmitted signal to construct two signal-adapted sub-dictionaries and to determine the weights. Then the WMP algorithm is applied to remove the jamming component from the mixture. Experimental results verify the validity of the presented method. By comparison of the pulse compression performance, the simulation results shows that the presented method is superior to the method of frequency domain cancellation （FDC） when the jamming-to-signal ratio （JSR） is lower than 15 dB.

Cognitive anti-jamming receiver under phase noise in high frequency bands

This paper investigates the jamming sensing performance of the simultaneous transmit and receive based cognitive anti-jamming(SCAJ) receiver impaired by phase noise in local oscillators(LO) over fading channels. Firstly, energy detection(ED)based on the jamming to noise ratio(JNR) of the high frequency bands SCAJ receiver with phase noise under different channels is analyzed. Then, the probabilities of jamming detection and false alarm in closed-form for the SCAJ receiver are derived. Finally,the modified Bayesian Cramer-Rao bound(BCRB) of jamming sensing for the SCAJ receiver is presented. Simulation results show that the performance degradation of the SCAJ system due to phase noise is more severe than that due to the channel fading in the circumstances where the signal bandwidth(BW) is kept a constant. Moreover, the signal BW has an effect on the phase noise in LO, and the jamming detection probability of the wideband SCAJ receiver with lower phase noise outperforms that of the narrowband receiver using the same center frequency. Furthermore,an accurate phase noise estimation and compensation scheme can improve the jamming detection capability of the SCAJ receiver in high frequency bands and approach to the upper bound.

Artificial Noise Aided Polar Codes for Physical LayerSecurity

The secrecy rates of the existing practical secrecy coding methods are relative low to satisfy the security requirement of 5 G communications.We propose an artificial noise(AN) aided polar coding algorithm to improve the secrecy rate.Firstly,a secrecy coding model based on AN is presented,where the confidential bits of last transmission code block are adopted as AN to inject into the current codeword.In this way,the AN can only be eliminated from the jammed codeword by the legitimate users.Since the AN is shorter than the codeword,we then develop a suboptimal jamming positions selecting algorithm with the goal of maximizing the bit error rate of the eavesdropper.Theoretical and simulation results demonstrate that the proposed algorithm outperforms the random selection method and the method without AN.

The Response to Arbitrarily Bandlimited Gaussian Noise of the Complex Stretch Processor Using a Conventional Range-Sidelobe-Reduction Window

This paper derives a mathematical description of the complex stretch processor’s response to bandlimited Gaussian noise having arbitrary center frequency and bandwidth. The description of the complex stretch processor’s random output comprises highly accurate closed-form approximations for the probability density function and the autocorrelation function. The solution supports the complex stretch processor’s usage of any conventional range-sidelobe-reduction window. The paper then identifies two practical applications of the derived description. Digital-simulation results for the two identified applications, assuming the complex stretch processor uses the rectangular, Hamming, Blackman, or Kaiser window, verify the derivation’s correctness through favorable comparison to the theoretically predicted behavior.

Optimal Periodic Pulse Jamming Signal Design for QPSK Systems

The problem of optimal periodic pulse jamming design for a quadrature phase shift keying（QPSK）communication system is investigated.First a closed-form bit-error-rate（BER）of QPSK system under the jamming of pulse signal is derived.Then the asymptotic performance of the derived BER is analyzed as the signal-to-noise ratio（SNR）grows to infinity.In order to maximize the BER of the QPSK system,the optimal parameters of periodic pulse jamming signal,including the duty cycle and signal-tojamming power ratio（SJR）,are found out.Numerical results are presented to verify our analytical results and the optimality of our design.

智能反射面辅助的抗干扰安全通信系统鲁棒资源分配算法

为了解决恶意干扰攻击、窃听和不完美信道状态信息造成的通信质量降低和安全性差等问题,该文提出一种智能反射面(IRS)辅助的抗干扰安全通信系统鲁棒资源分配算法。首先,基于合法用户的最小安全速率约束、最大发射功率约束和IRS相移约束,在非法节点不完美信道状态信息、干扰器波束成形向量未知的情况下,构建了一个联合优化基站的波束成形向量、人工噪声的协方差矩阵和IRS的相移矩阵的鲁棒资源分配问题。其次,为了求解该非凸问题,利用交替优化、Cauchy-Schwarz不等式、连续凸逼近和泰勒级数展开等方法,将原问题转化为易于求解的凸优化问题。仿真结果表明,与传统算法相比所提算法能有效提高系统安全性、降低功率开销、提高抗干扰裕度,且在一定信道误差范围内能够减低约35%的保密中断概率,具有较强的鲁棒性。

基于多维小波特征的有源雷达欺骗干扰识别

针对跟踪工作模式下常见雷达有源欺骗干扰识别问题,通过分析雷达信号和干扰模型,提出一种基于多维小波特征的识别算法。对目标回波多个相干处理间隔中的首个脉冲重复间隔内信号采样累积,构成一维离散序列,利用Mallat算法提取多尺度小波系数,计算不同尺度下小波系数的移位相关系数,并组成特征向量用于分类识别。构建不同参数的信号样本仿真,在信噪比为-5 dB时仍有高于80%的识别正确率。该算法能将距离假目标干扰和距离拖引干扰有效识别,证明了算法的准确性、通用性和严谨性。此外,针对实际情况,可以调整特征向量维度,选择更适合的母小波函数,进一步优化干扰识别效果。

基于噪声卷积调制的SAR多区域灵巧干扰方法

针对传统噪声卷积干扰存在的压制区域位置在方位向上不能灵活控制的缺陷,提出一种基于噪声卷积调制的SAR多区域灵巧干扰方法。该方法对截获信号进行距离向移频、方位向移相以及与噪声模板的卷积调制处理,以控制压制区域的位置;后对截获信号进行不同频率、相位的噪声卷积调制处理,以控制压制区域的数量。理论和仿真结果表明,所提方法实现了压制区域位置在方位向、距离向上的灵活控制,并实现了单一干扰机对多个待掩护区域的干扰,提高了干扰增益,干扰效果较好,对实际工程应用具有一定的参考价值。

利用接收机载噪比测量值的GNSS干扰源定位技术

由于GNSS信号在抵达地面时信号强度较低,极易遭受无意或蓄意的人为干扰,严重时甚至会导致导航和定位服务不可用,因此,定位和消除干扰源显得尤为重要.面向常见的压制式干扰,针对目前的定位方法主要是对原始采样信号进行处理,实现起来往往具有设备复杂、计算量大、成本高的问题.本文提出了一种利用普通商用接收机的载噪比(carrier-to-noise ratio,C/N0)测量值进行GNSS干扰源定位的方法,通过C/N0测量值估计干扰信号强度差,进而解算出干扰源位置.实测结果表明:视距条件下,在约11400 m2的监测区域中,该方法能够达到13.17 m的平均绝对定位误差,且耗时较少,可实现干扰源的有效定位.所提方法无需对接收机进行软硬件的改动,实现简单,成本低,利于工程应用.

基于ADBF的多通道SAR抗干扰样本选择方法

针对多通道SAR抗干扰问题,可以利用空域自由度通过自适应波束形成技术达到增强期望信号、抑制干扰的目的。在波束形成过程中,计算各阵元的最优权矢量时,需要通过选取干扰和噪声的数据样本估算干扰加噪声协方差矩阵。若选择的数据样本中掺杂目标信号,则目标信号将会被误判为干扰并被抑制。针对多通道SAR抗干扰过程中需要注意的样本选择问题,通过消除方位向频域中主杂波宽度内的目标分量,得到干扰加噪声数据样本,继而计算协方差矩阵,并进行波束形成。通过实测数据成像结果及干噪比和信噪比指标验证了提出的自适应样本选择方法的有效性。与直接样本选择方法相比,自适应样本选择方法在信噪比上提高了近8 dB,干噪比下降了近6 dB,说明了该方法有效地保留了目标信号,抑制了干扰信号。

基于载噪比同步变化的北斗欺骗检测方法

欺骗干扰已经成为北斗卫星导航系统安全性的一个严重威胁。针对北斗系统面临的欺骗干扰问题,建立二元假设检验模型。由于施加单一天线发射的欺骗干扰后,当前观测频点下各高俯仰角可见星的载噪比值会产生相同的变化趋势,所以基于此变化规律提出了一种利用K-means聚类算法进行分析的北斗卫星信号欺骗干扰检测方法,并给出了施加欺骗载噪比变化域的定义。最后通过在外场搭建实验环境,对实采数据进行了实验验证。实验结果表明,本方法对于欺骗功率优势≥6 dBm的大功率优势欺骗信号的检测概率可以达到95%以上,为提高接收机抗干扰能力提供了有益参考。

Noise attenuation of frequency-modulated multi-rotor using sound field reproduction

Multi-rotor aircraft has great potential in urban traffic and military use and its noise problem has attracted more attention recently.Multi-rotor aircrafts are typically controlled by changing the rotation speeds of the rotors.To reduce the noise of multiple frequency-modulated rotors,a global noise attenuation method is proposed in this study.First,the fast prediction method is used to estimate the global noise of the multirotor with different configurations online.Meanwhile,the sound field reproduction method is used to obtain the control signal of the loudspeaker array to achieve global noise attenuation.Then,the influence of array arrangement on noise reduction is analyzed in the acoustic modal domain,which reveals that different optimization models are needed to minimize the noise power or/and the noise pressure in some directions when the scale of the array is limited.Next,to improve the real-time performance of the system,the online calculation of the optimal control signal is transformed into the offline design of the optimal filter,which satisfies the target frequency-domain characteristics.Finally,the experimental results of the noise of a model quadrotor in the anechoic chamber were consistent with the predicted results.The simulation results of noise attenuation for the quadrotor show that the method proposed reduced the global noise power by about 13 dB.Moreover,the noise region radiated from the quadrotor to the ground with the boundary of 40 dB was reduced to 8.4%of that before control.

一种基于多普勒和距离维调制的SAR雷达二维乘性噪声干扰方法

针对合成孔径雷达(Synthetic Aperture Radar,SAR)二维相干成像特点,采用二维乘性噪声干扰实现了距离维和方位维干扰的解耦合,灵活构造乘性噪声信号。形成一连串二维噪声假目标,产生的噪声亮斑点迹可控,得到的干扰回波作用在SAR雷达恒虚警率(Constant False Alarm Rate,CFAR)检测平面上,能量分布可控,可以对更普遍的SAR雷达检测算法起效。二维乘性噪声干扰方法作用于距离维的脉冲压缩和方位维的多普勒维调制,使得干扰信号的能量密度集中,提高了干扰效费比。

雷达、通信、干扰信号一体化检测识别技术研究

雷达信号、通信信号及其干扰信号在时域和频域都有各自的特点,当这些信号在时域、频域相互交叠时,传统的信号检测和识别算法很难将这些信号进行有效地分离,影响信号检测和参数测量。针对雷达信号、通信信号及其干扰信号在时、频域的特点,研究雷达信号、通信信号及其干扰信号在时域、频域混叠情况下的信号检测、参数测量及其信号类型识别方法。

基于某ISAR的压制干扰效果分析

逆合成孔径雷达(ISAR)作为高分辨率微波成像雷达,已经广泛应用于目标识别及精确制导。为更有效地保护目标,对于ISAR干扰的研究已成为重要的研究课题,在常见干扰方式上,对于ISAR干扰效果的评估显得尤为重要。分析常见的4种ISAR噪声压制干扰的干信比临界点,得出结论性数据,为工程应用提供有效干扰ISAR的干信比(JSR)参考门限。

抗干扰技术在卫星通信工程中的应用研究

在卫星通信工程中,日益严峻的信号干扰问题严重影响着信息传输的稳定性和安全性。针对这一问题,文章深入研究了抗干扰技术在卫星通信工程中的具体应用,探讨时频分析、阵列信号处理、自适应滤波以及前向纠错等多种抗干扰策略。经实验验证,实施抗干扰技术后,误码率(Bit Error Rate,BER)降至10-8,信噪比(Signal to Noise Ratio,SNR)平均增长了3.67 dB,性能远超未优化状态。

Adaptive Threshold Clipper Combining Receiver for Fast Frequency Hopping Systems during Partial-Band Noise Jamming

Diversity combining technologies are analyzed for fast frequency-hopping spread spectrum systems during partial-band noise jamming to develop a novel combining receiver called an Adaptive Threshold Clipper Combining Receiver (ATCCR). The optimal clipping level for an ATCCR is analyzed, computed, and compared with several other diversity combining technologies. Since the ATCCR can estimate the power of the jamming and the number of jammed frequency cells to adaptively adjust the clipper's threshold, the system performance using the adaptive threshold clipper combining technique can be greatly improved.

基于自适应递推滤波的高压输电线路行波故障定位方法

针对传统高压输电线路测距精度差且行波法易受噪声因素影响等问题,提出了一种基于自适应递推滤波算法的高压输电线路行波故障定位方法。该方法首先经高通滤波处理后采集电流行波信号,粗定行波波头位置,选取故障前数据估计噪声的分布参数;然后基于噪声分布参数构建自适应递推滤波器对信号进行滤波;最后结合滤波后的信号与噪声参数进行比较,实现波头标定。在此基础上,结合双端测距原理实现故障点定位。仿真分析表明,所提出的方法在不同的故障条件下均可准确检测出行波信号;在弱行波信号含噪情况下,相比于小波变换,自适应递推滤波算法能有效提高输电线路故障行波定位的准确性。

一种融合噪声网络的深度强化学习通信干扰资源分配算法

针对传统干扰资源分配算法在处理非线性组合优化问题时需要较完备的先验信息,同时决策维度小,无法满足现代通信对抗要求的问题,该文提出一种融合噪声网络的深度强化学习通信干扰资源分配算法(FNNDRL)。借鉴噪声网络的思想,该算法设计了孪生噪声评估网络,在避免Q值高估的基础上,通过提升评估网络的随机性,保证了训练过程的探索性;基于概率熵的物理意义,设计了基于策略分布熵改进的策略网络损失函数,在最大化累计奖励的同时最大化策略分布熵,避免策略优化过程中收敛到局部最优。仿真结果表明,该算法在解决干扰资源分配问题时优于所对比的平均分配和强化学习方法,同时算法稳定性较高,对高维决策空间适应性强。

无监督时频信息结合的舰船辐射噪声信号抗诱饵干扰方法

舰船辐射噪声信号是感知目标舰船的重要方式之一。诱饵信号通过模仿目标舰船辐射噪声,混淆感知系统以掩护目标舰船完成战略目标。如果可以通过对舰船辐射噪声与诱饵信号识别方式实现抗干扰,将大大提高战时敌方舰船识别效率,从而提高战术行动的效率和成功率。将抗诱饵干扰问题转化为单类分类问题,尝试采用深度学习范式给出解决方法。以此为背景,提出无监督时频信息结合的舰船辐射噪声信号抗诱饵干扰方法。构建针对舰船辐射噪声信号时域、时频域数据的对抗生成网络结构。采用对抗训练策略捕捉舰船辐射噪声信号的时域、时频域联合分布,提高模型针对舰船辐射噪声信号的表示学习能力,最终实现端到端的舰船辐射噪声信号单类分类任务。实验数据由外场实验模拟产生诱饵信号采集而来。研究结果表明:在无监督条件下的AUC值为0.84,相对于单类分类基线模型高出0.17,可以实现对舰船辐射噪声信号抗诱饵干扰。