一种导航宽带抗干扰中的阵列幅相误差校正算法

针对复杂电磁环境下抗干扰导航接收机中存在的幅相误差问题,提出一种幅相误差有源校正的导航接收机抗干扰算法;该算法通过干扰和幅相误差构建阵列幅相误差数学模型;然后基于加权子空间拟合原理和最小二乘的方法估计阵列幅相误差系数;最后利用线性约束最小方差(LCMV)算法对修正的之后的接收数据进行干扰的抑制;并明确提出了导航抗干扰接收机的通道修正的解决方案。理论分析和仿真实验表明,估计的幅相误差系数与实际幅相误差非常接近;此方法可以准确在干扰方向上形成零陷并保留导航信号;信噪比在-10 d B的时候,幅相误差估计值逐渐收敛于真实值;并且随着信噪比的增加幅相误差估计精度也逐渐提高。所提算法能有效提高存在幅相误差通道的抗干扰的性能。     

一种新的降秩广义旁瓣相消器

了减少广义旁瓣相消器的计算量,提出了一种新的降秩广义旁瓣相消器,利用特征子空间构建阻塞矩阵,设计广义旁瓣相消器,比以往的降秩广义旁瓣相消器能够减少更多的计算量,仿真实验结果验证了该方法的有效性。     

淋巴细胞脉络丛脑膜炎病毒在实验大鼠中的感染状况

目的对实验室留存的大鼠血清样本进行淋巴细胞脉络丛脑膜炎病毒(LCMV)抗体检测,调查LCMV在我国实验大鼠中的感染情况。方法依据现行国家标准中规定的免疫荧光试验(IFA)方法对我实验室保存的172份大鼠血清样本(包括48份无级别、100份清洁级和24份SPF级大鼠血清样本)进行LCMV抗体检测。结果无级别大鼠血清样本(n=48)15份阳性,阳性率为33.25%,强阳性样本滴度可达1∶1280;SPF级及清洁级大鼠血清样本全部阴性。结论大鼠可以感染LCMV,实验动物等级标准应增加对大鼠LCMV的检测。     

Adaptive monopulse beamforming with partial parallel structure

A new recursive algorithm with the partial parallel structure based on the linearly constrained minimum variance (LCMV) criterion for adaptive monopulse systems is proposed. The weight vector associated with the original whole antenna array is decomposed into several adaptive weight sub-vectors firstly. An adaptive algorithm based on the conventional LCMV principle is then deduced to update the weight sub-vectors for sum and difference beam, respectively. The optimal weight vector can be obtained after convergence. The required computational complexity is evaluated for the proposed technique, which is on the order of O(N) and less than that of the conventional LCMV method. The flow chart scheme with the partial parallel structure of the proposed algorithm is introduced. This scheme is easy to be implemented on a distributed computer/digital signal processor (DSP) system to solve the problems of the heavy computational burden and vast data transmission of the large-scale adaptive monopulse array. Then, the monopulse ratio and convergence rate of the proposed algorithm are evaluated by numerical simulations. Compared with some recent adaptive monopulse estimation methods, a better performance on computational complexity and monopulse ratio can be achieved with the proposed adaptive method.     

套式PCR检测淋巴细胞脉络丛脑膜炎病毒(LCMV)方法应用

目的检测目前小鼠和地鼠中淋巴细胞脉络丛脑膜炎病毒的感染情况。方法采用套式PCR方法对小鼠和地鼠脑及小鼠脏器进行扩增,检测LCMV基因;同时对血清进行ELISA试验,将两种方法的结果进行比较。结果从小鼠的脾脏和肾脏中检测到NP基因的存在,检出率2/148;ELISA检出率5/148。结论PCR与ELISA检测方法相结合,准确率高,证明目前小鼠中存在LCMV的感染。     

淋巴细胞脉络丛脑膜炎病毒(LCMV)PCR检测方法的建立与初步应用

目的建立检测淋巴细胞脉络丛脑膜炎病毒(LCMV)的PCR方法。方法根据LCMV CDNA S片段的GPC和NP基因设计合成4对引物,对标准毒株进行套式PCR扩增并克隆测序,并对15份已知阳性或阴性小鼠鼠脑进行检测。结果目的片断与LCMV cDNA序列99%同源,对鼠脑的检测结果为10只阳性,5只阴性。结论检测小鼠鼠脑LCMV的结果准确,证明套式PCR能够应用于LCMV的实验室检测。     

A Blind Adaptive Jamming Canceller Using Antenna Array for GPS Receiver

Traditional beamformers need to know the incident angle of the desired signal leading while its ability to handle interference is limited. In this paper, the constrained steer vector of linearly constrained minimum-variance (LCMV) beamformer is modified to make sidelobe null to direction of powerful jammer. In addition, the state-space concept is used to describe the anti-jammer filter, and Kalman filter algorithm is deduced by building the observation model and measurement equation. The new method is more efficient on computation and more robust to survive environment with large scale variation in interference strength. Finally, simulation results shows that the new approach can form the null with its depth in proportion to power in direction of jammer, and has steady convergence process. The novel method can effectively improve the signal-to-jammer-plus-noise power ratio (SJNR) of GPS signals to make the correlation peak easy to track.     

基于线性约束最小方差原则的稳健快速自适应脉冲压缩方法

针对线性调频信号在距离单元内的回波采样点与目标点失配, 即采样失配的情况下, 自适应脉冲压缩性能下降的问题, 对快速自适应脉冲压缩(fast adaptive pulse compression, FAPC)方法进行改进, 提出一种基于线性约束最小方差(linearly constrained minimum variance, LCMV)原则的连续分块FAPC (contiguous block FAPC, CFAPC)方法。该方法将自适应波束形成方法类比到自适应脉冲压缩滤波方法中, 首先在最小方差无畸变响应(minimum variance distortionless response, MVDR)原则保持增益的前提下增加零点约束条件, 加宽零点凹口的宽度; 而后对分块的协方差矩阵设置置零条件, 抑制旁瓣能量, 实现在采样失配情况下保持稳健的目的。实验结果表明, 在脉内多普勒频移和采样失配同时存在的情况下, 所提方法可以更好地抑制目标的距离旁瓣, 具有较好的稳健性。     

一种自适应调零阵的LCMV算法

详细推导了基于功率倒置阵列的线性约束最小方差(LCMV)算法及其递推公式,避免了矩阵求逆的复杂运算。然后在Matlab环境里构建了仿真模型来模拟实际的接收环境和复现阵列接收到的信号,对均匀线阵和圆阵都做了仿真,并得到了相应的阵列波束图,为自适应天线的实用设计提供了参考和依据。仿真结果表明:该算法收敛速度快、易于实现,利用LCMV算法作为自适应算法的功率倒置阵列抗干扰方案适合在强干扰的环境下工作,干扰越强,其对应的零陷越深。