共查询到20条相似文献,搜索用时 156 毫秒
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卫星信号经过长距离传播,信号能量损耗严重,到达地面的功率很弱,容易受到各种干扰的影响。脉冲干扰为常见的干扰类型,所以针对不同功率、不同周期,以及不同占空比的脉冲干扰信号,通过接收前端采集受脉冲干扰的GPS L1信号,利用软件接收机及多相关器生成技术,详细分析了脉冲干扰对接收机信号捕获与跟踪性能的影响。分析结果表明,周期为1ms的脉冲干扰信号,能对接收机产生强烈的干扰效果,捕获图中的噪声明显增大;跟踪过程中,载噪比和相关值突发性减小,造成跟踪数据异常。而长周期的脉冲信号仅在脉冲到达时影响接收机的捕获和跟踪,但由于信号跟踪不能连续进行,导致伪距观测量的不连续与导航数据不能正常解码,从而干扰接收机。 相似文献
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宋福臣 《中国民航学院学报》1988,(4)
本文主要介绍计算机技术在机载上引导无源干扰投放系统中的应用。在大量各种类型雷达投入工作,电磁波信号日趋密集与复杂的情况下,如何能实时准确地分选、识别各种辅射源,确定辐射源威胁程度和方位,及时向飞行员发出告警,并能实时引导、控制无源干扰的投放装置。为了实现上述任务,必须借助于现代电子计算机技术。有关资料指出,现代电子战中的电磁波信号密集,每秒可达到10~5~10~6个脉冲之多,这就要求具有高速输入输出能力和处理能力的计算机。但目前尚未解决。本文采用硬件采集、滤波、双通道缓冲存贮器和软件相结合的技术,在高密集数据的时空域中,实现了对目标进行实时采集和分选的任务,并提出了几种可行的实施方案。 相似文献
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目前我国的化铣工艺正处于由一般化铣向精密化铣的发展中,各种添加剂加入化铣液中,干扰了原有的成分分析方法的准确性。本文设计分析前预处理新工艺,可解决分析中的难点,介绍采用常规工业分析方案,分析铝离子总量,添加剂Na2S及三乙醇胺含量详细工艺过程,为推广精密化铣新工艺提供了可靠的分析技术。 相似文献
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提出采用加速度反馈方案,在无需加大系统带宽的情况下提高系统的动态刚度,从而提高了系统对周期性干扰的抑制能力。仿真结果表明,与传统PID控制相比,采用加速度反馈确实能够较好地抑制系统中的周期性干扰。 相似文献
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目前我国的化铣工艺正处于由一般化铣向精密化铣的发展中,各种添加剂加入化铣液中,干扰了原有的成分分析方法的准确性。本文设计分析前预处理新工艺,可解决分析中的难点,介绍采用常规工业分析方案,分析铝离子总量、添加剂Na2S及三乙醇胺含量详细工艺过程,为推广精密化铣新工艺提供了可靠的分析技术。 相似文献
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为了解决民航地空通信受到无线电干扰的问题,提出了双通道恒模干扰抑制自适应抑制接收机的设计实现方案。接收机中的信号处理平台在FPGA中实现自适应干扰抑制,使用DSP判断恒模算法输入信号是否存在干扰,以及对恒模算法输出信号进行属性判断以防止误捕获。再配以具有VHF信号接收功能的射频前端电路,实现接收、干扰抑制、解调地空通信信号的功能。系统测试表明,双通道恒模干扰抑制接收机能够自适应地抑制恒模干扰。 相似文献
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后体尾喷流干扰问题的准确模拟,对大尺度一体化飞行器气动力预测及后体尾喷流干扰机理认识至关重要。为了研究后体尾喷流干扰问题,本文基于相似理论,开展了模拟内外流相似参数的喷流干扰实验方案研究。提出了采用CF4+Air混合气体形式,模拟超然冲压发动机出口热态喷流的比热比等相似参数,建立了模拟真实条件下的喷流干扰问题的模拟方案。采用数值仿真软件对飞行条件和风洞条件下后体尾喷流干扰问题进行了数值模拟,从数值模拟结果来看,模拟内外流相似参数的喷流干扰实验方案是完全可行的。 相似文献
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C. -G. Fälthammar 《Space Science Reviews》1974,15(6):803-825
Space-related laboratory experiments can play an important role as a complement to observations and active experiments in the magnetosphere. Excluding laboratory experiments for mere developing or testing of techniques for space experiments, we may distinguish between two major types: (1) partial scale model experiments and (2) experiments for clarifying basic plasma physical processes known or expected to be important in the magnetosphere (but without the ambition to simulate actual space configurations). The limitations and potentialities of both types are discussed and examples of experiments are given. It is concluded that there should be an increasing need for the experiments of the second type. In particular, they are needed for the clarification of the response of a thin plasma to electric fields and its ability to carry electric currents. This encompasses such key questions as the nature and role of anomalous resistivity (and electron runaway in its presence), the possible formation of double layers (and the acceleration processes associated with them) and rapid dissipation of magnetic-field energy. 相似文献
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文章综述了固体火箭发动机喷管烧蚀实验研究的现状;提出一种小型矩形烧蚀实验器的研制方案,着重从实用性及经济性方面做了论证;并介绍了实验结果. 相似文献
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本文探讨了作为模态试验方法之一的多点激振技术。针对某些实验仪器存在的相位移动问题,提出了一种新的多点激振调力方案,并建议了一种识别纯模态下各模态参数的实用方法。经过计算和实验的考核,说明本文方法对于一般结构进行多点激振试验都是适用的。 相似文献
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基于量纲分析和最优设计的毁伤响应函数获取 总被引:1,自引:0,他引:1
毁伤响应函数的获取是毁伤效能评估中至关重要的研究内容,其主要研究方法是试验归纳。为在原型试验样本极少的条件下,获取高效的毁伤响应函数,本文一方面应用量纲分析开发物理模型信息,并应用缩比试验拓展试验技术;另一方面构建了缩比试验与原型试验之间差异的参数化模型和融合评估模型。在这些工作的基础上提出两种试验的联合一体化最优设计方法,科学地设计试验,提高试验的效费比。给出了相互差异建模和一体化最优设计的例子,说明了本文方法的优势。 相似文献
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Ball Henry W. Harris H. G. Hiatt Jay 《IEEE transactions on aerospace and electronic systems》1967,(2):285-296
As part of a hypervelocity instrumentation development program, it was desirable to include a radiometer system for measuring absolute radiation from projectile flow fields. A system employing a photomultiplier tube was designed, and laboratory and range experiments were conducted to investigate its performance characteristics. The laboratory experiments show that the linearity, saturation, and noise characteristics are suitable for this measurement; the system bandwidth is adequate to allow low frequency calibrations to be applied to high frequency measurements; and a derived expression for radiometer sensitivity variation as a function of photomultiplier supply voltage is reasonably correct. The results of the range experiments imply that the system response is sufficient to reproduce accurately input pulses as narrow as one microsecond and that a particular analytical technique for calculating the form of the radiative input to the radiometer from the projectile stagnation region is valid. Principles involved in the design of photomultiplier radiometer circuits of this type are discussed in detail. 相似文献
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W. P. Olson 《Space Science Reviews》1974,15(6):899-904
Several experiments that can be performed in Earth orbit with a superconducting magnet are discussed. They are divided into 2 classes, pure plasma physics experiments that can be performed in near Earth orbit and planetary magnetosphere simulation experiments that are best conducted in weak background fields distant from the Earth. The later are all based on the Minimag concept where plasma is directed toward a large dipolar magnet in Earth orbit to form a model miniature magnetosphere. Several experiments that cannot be performed in ground based laboratories and tests that cannot be made in the real magnetosphere can be carried out in Earth orbit. The creation of a miniature model of the magnetosphere (Minimag) forms the basis for several of these experiments. 相似文献
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A new technology for reducing turbulent skin friction, called the Microblowing Technique (MBT), is presented. Results from proof-of-concept experiments show that this technology could potentially reduce turbulent skin friction by more than 50% of the skin friction of a solid flat plate for subsonic and supersonic flow conditions. The primary purpose of this review paper is to provide readers with information on the turbulent skin friction reduction obtained from many experiments using the MBT. Although the MBT has a penalty for obtaining the microblowing air associated with it, some combinations of the MBT with suction boundary layer control methods are an attractive alternative for a real application. Several computational simulations to understand the flow physics of the MBT are also included. More experiments and computational fluid dynamic (CFD) computations are needed for the understanding of the unsteady flow nature of the MBT and the optimization of this new technology. 相似文献
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