共查询到20条相似文献，搜索用时 156 毫秒
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恒模波束形成算法是利用期望信号本身的特性实现波束形成的,而不需要参考信号,这种盲波束形成算法主要用于移动通信系统中,最小二乘恒模算法(LSCMA)是一种能够快速收敛的恒模算法。本文首先介绍了最小二乘恒模算法基本原理和权值迭代公式,然后通过计算机仿真实现了该算法,给出了仿真结果,并研究比较了算法取不同参数时的仿真结果,对静态LSCMA和动态LSCMA算法的收敛特性也进行了比较。 相似文献
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针对阵列信号中部分自适应信号处理问题,提出了一种新的基于平滑阵列的降维方法. 该方法将全阵列平滑处理,通过分割成相互重叠的子阵达到降维的目的. 该波束形成器使用了两级加权的结构. 根据方向图相乘原理,天线方向图是两级加权矢量独立产生的方向图的乘积,此波束形成器可以等效为一种空域滤波器的级联形式. 通过大量的计算机仿真验证了此方法的有效性和优越性. 相似文献
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民航甚高频通信经常受到各种各样的干扰,严重影响了民航飞行的正常进行。文章首先建立了符合甚高频通信特点的实际模型,然后建立了双通道干扰抑制系统,并在满足窄带假设地前提下提出了一种基于递归最小二乘恒模阵列的的抗干扰方案,这种阵列比以往使用最陡下降恒模阵列具有更快的收敛速度和数值稳定性。计算机仿真数据实验和实际采集的数据实验也证明了这种方法的有效性。 相似文献
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随着麦克风阵列在室内声场分析、声场再现、语音通信中的广泛应用,球面谐波分解在阵列信号处理中的地位变得更加重要。针对球面阵列的球面谐波分解是近年发展起来的波束形成新技术,它还可以扩展到线阵和环形阵等其它阵形中。从球面傅里叶变换着手,在球面谐波域内对不同条件下波束形成算法的原理、性能及其在阵列信号处理中可能的应用进行了全面的综述。 相似文献
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声自导技术的基础是波束形成技术,对波束形成技术的研究能够让我们更好地提高水下航行器的自动导引能力。本文首先对声自导系统的模型和基本职能进行了简单介绍,然后对波束形成技术和方位估计（参数估计）技术在无人水下航行器声自导技术上的应用进行了初步的研究,为我们将来发展新型无人水下航行器提供了一定的理论基础。 相似文献
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<正>宽带数字阵列侦察系统利用采样后的数字信号进行信号合成，具备较高的幅度和相位控制精度，可瞬时形成多个宽带数字波束，兼备宽空域覆盖和高天线增益的特点，解决了传统侦察设备中宽空域覆盖与高天线增益相互矛盾的问题。这些特点使其广泛应用于电子侦察、频谱管控等领域。数字波束形成（Digital Beam Forming,DBF）算法是宽带数字阵列侦察系统的核心技术之一。复杂的电磁环境要求其形成的波束具有高主瓣增益、窄波束、低旁瓣增益等特点。然而，目前已有的旁瓣控制DBF算法， 相似文献
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在车载系统、电话会议与多媒体会议等语音处理系统中,麦克风接收到的语音信号常常受到环境噪声的干扰,严重影响了通话质量。为了能有效地抑制相干与非相干噪声的干扰,该文将多级维纳滤波器与传统的广义旁瓣抵消器(GSC)相结合,提出了基于后置多级维纳滤波器的自适应波束形成方法。仿真结果表明,相对于传统的麦克风阵列语音增强方法而言,本文介绍的方法具有更好的去噪效果。 相似文献
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The paper describes a machine for determining the real and complex roots of higher-degree algebraic equations. The principle of operation is found in the correspondence between sine wave quantities and complex numbers. The particular machine is designed for equations of the eighth degree, and finds all the roots with engineering accuracy in the space of a few minutes.Though designed primarily with a view to determining the indicial admittance of electric networks, the machine should find utility in other fields of applied mathematics as well. 相似文献
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常数模算法（constant modulus algorithm,CMA）能够很好地克服无线信道引入的符号间干扰（ISI）,在信道均衡中广泛应用,但存在稳态误差大,相位旋转的问题;MMA算法解决了CMA算法的相位旋转问题,但仍然有较大的稳态误差。为了克服以上缺点,在研究各种算法的基础上,引入非线性函数来构造步长调整参数,计算机仿真结果表明,相比传统算法,变步长盲均衡算法有较快的收敛速度和更好的均衡效果。 相似文献
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A variety of the web-mining techniques are now being extensively utilized to extract useful knowledge about customer behaviors on the Internet. However, the naive interpretation of the web-mining results would lead to poor decision on customer behaviors, which is likely to cause waste of time and efforts on managing electronic commerce strategy. To overcome this pitfall, this study proposes using the cognitive map-based interpretation of the web-mining results. Conventional approach to obtaining the web-mining results is based on the association rule approach (ARA), while the cognitive map approach (CMA) is believed to provide more robust support in interpreting the web-mining results. Therefore, to compare the interpretation capability of the two approaches, the four constructs such as perceived usefulness, causality, information richness, users’ attitude and intention to use the approaches are adopted in the research model and tested against the questionnaire data. The test results obtained through applying the structural equation models reveal that CMA is comparable to ARA and the cognitive map has a great potential in helping enrich the interpretation of the web mining results and build more effective Internet business strategy. 相似文献
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本文将“负责任研究与创新”放在欧洲政策思想史的背景中来解读,认为其核心内涵是通过公共协商的方式来塑造目标和价值,并依此塑造科技创新的路径和方向,从而实现社会和谐发展。这一核心内涵并没有超出哈贝马斯在1960年代关于科学技术与政府统治之关系的思想,即关于政府支持科技创新的三重合法性辩护、对共同目标和科技发展路径的双重塑造,所增加的新内容就在于如何实现这双重塑造的具体方法。 相似文献
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科学媒体塑造科学家形象的思考与启示 《科学学研究》2022,40(1):22-28
媒体对科学家形象的良好形塑不仅关乎科学家精神的厚植与弘扬,更深刻影响公众对科学家乃至科学的整体认知与态度。研究综合运用定性和定量分析方法,以《中国科学报》和Wiely 2015-2020年科技人物报道为数据源,探索分析了国内外科学媒体在中国科学家形象塑造时的异同。结果显示:《中国科学报》科技人物报道以叙事记叙性通讯为体裁,男性且功成名就的科学家为主体,科学家形象塑造以展现宏观科学精神为主,日常生活与个性挖掘为辅;Wiely以谈话实录性通讯为核心叙事方式,聚焦当代青年科技精英,侧重对科学家职业和个性特征、科学与人文精神的共同勾画。两大科学媒体在科技人物报道对象及其形象塑造中均存在一定的性别刻板。据此,对科学媒体中科学家形象的塑造路径与策略提出了反思。 相似文献
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《Journal of The Franklin Institute》2021,358(16):8639-8655
Interconnection and damping assignment passivity-based control scheme has been used to stabilize many physical systems such as underactuated mechanical systems through total energy shaping. In this method, some partial differential equations (PDEs) related to kinetic and potential energy shaping shall be solved analytically. Finding a suitable desired inertia matrix as the solution of nonlinear PDEs relevant to kinetic energy shaping is a challenging problem. In this paper, a systematic approach to solving this matching equation for systems with one degree of underactuation is proposed. A special structure for desired inertia matrix is proposed to simplify the solution of the corresponding PDE. It is shown that the proposed method is more general than that of some reported methods in the literature. In order to derive a suitable desired inertia matrix, a necessary condition is also derived. The proposed method is applied to three examples, including pendubot, VTOL aircraft, and 2D SpiderCrane. 相似文献
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A semi-blind adaptive space–time equaliser (STE) has recently been proposed based on a concurrent gradient-Newton (GN) constant modulus algorithm (CMA) and soft decision-directed (SDD) scheme for dispersive multiple-input multiple-output (MIMO) systems that employ high-throughput quadrature amplitude modulation signalling. A minimum number of training symbols, approximately equal to the dimension of the STE, is used to provide a rough initial estimate of the STE's weight vector. The concurrent GN based CMA and SDD blind adaptive scheme is then adopted to adapt the STE. This semi-blind STE has a complexity similar to that of the training-based recursive least squares (RLS) algorithm. For stationary MIMO channels, it has been demonstrated that this semi-blind adaptive STE is capable of converging fast to the optimal minimum mean square error STE solution. In this contribution, we investigate the performance of this semi-blind adaptive STE operating in Rayleigh fading MIMO systems. Our results obtained show that the tracking performance of this semi-blind adaptive algorithm is close to that of the training-based RLS algorithm. Thus, this semi-blind adaptive STE offers an effective and practical means to successfully operate under the highly dispersive and fading MIMO environment. 相似文献