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无线电频谱监测有助于促进频谱的高效利用,是发现和消除无线电干扰的重要技术手段。多通道无线电监测测向系统是在丰富的专业经验基础上设计的先进频谱监测、分析和测向系统,有助于提升无线电管理水平。 相似文献
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本文从提高当前卫星广播电视频谱监测系统综合监测能力和干扰信号识别能力角度出发,提出了一种基于先进的信号检测、识别、叠加分离处理算法的卫星频谱综合监测和干扰识别系统的功能设计方案,介绍了系统架构和关键技术,并给出了系统应用和测试结果.系统实践表明,可以有效、可靠地满足卫星广播电视安全播出的要求. 相似文献
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提出一种基于共享数据库技术的空间电磁环境监测系统方案,设计机载现场可编程门阵列(FPGA)核心频谱采集分析模块,开发信号传输链路、数据处理及系统显示控制软件。基于共享数据库技术,利用无人机(UAV)机载信号采集模块,将测量到的空间频谱数据和地理位置信息实时回传;终端显示控制系统将监测数据分别以频谱图和辐射热图的方式,在数字地图上对所测空间区域电磁频谱分布实时直观显示,将电磁频谱监测从地面扩展到三维空间。试验证明,本系统可高效灵活地监测空间频谱的实时变化情况,为频谱管理、空间电磁环境实时监测以及发射源侦测定位提供重要的技术支撑。 相似文献
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为了降低研发成本,提高频谱系统的灵活性和缩短研制周期,提出了一种基于软件无线电的嵌入式频谱监测系统。首先研究了系统硬件平台组成和特点,在此基础上设计了一种灵活的软件定义系统架构;然后考虑到硬件平台自身性能的限制,重点研究了频率偏移校正、频谱扫描策略等关键技术,分别提出了基于GSM信号和温度传感器的频偏校正方法和基于相关性的扫频策略;最后通过具体实验,对系统性能进行验证与评估,结果表明所提出的频偏校正方法能够将绝对平均频偏控制在1.749×10-6以内,所设计的基于相关性的扫频策略对时变信号的频谱监测效果最好。 相似文献
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微波技术在视频图像无线传输中的应用 总被引:3,自引:0,他引:3
电视监控在生活和工作中得到了广泛的应用,然而在某些环境中,由于成本或地形所限,有线电视监控无法实现.无线网络产品的快速发展和视频压缩标准的日渐完善对此提供了良好的解决方案.从工程的角度阐述了两种常用微波扩频技术的原理和特点,结合实际应用环境,对频点的选取、扩频技术的采用、天线的选择与调整提出了具体的方法. 相似文献
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为了解决目前城市频谱监测工作依赖于固定的监测站、持续性监测能力较差和频谱异常判定人工依赖性高等问题,提出了一种利用软件无线电搭配人工智能的新型频谱监测识别系统。首先利用GNURadio软件无线电平台,实现对某一频段的实时监测,获得所需要的频域数据;再利用一系列预处理手段,优化数据样本;最后,在前馈(BP)神经网络中,对频域状态波形进行识别,确定其信号数量、类型及信号所处信道,可以实现持续性频谱监测和智能频谱状态识别判定,其神经网络识别准确率高达96.1%。该系统可以嵌入手持频谱监测设备,并结合云端服务器持续智能地监测区域频谱环境。 相似文献
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本文针对异种网络之间的频谱共享问题,提出了基于跳频的自适应频谱共享方案.该方案中 ,频谱注册网络负责配置跳频频率表等跳频参数,并且将其在覆盖区域内广播.频谱共享网络中的可重构终端(CR-MTs)使用认知无线电(CR)技术对周围频谱进行监测,通过跳频频谱共享策略实现通信.本文设计了跳频频谱共享的信号发射模型和信令交换机制,提出了不同情况下的干扰避免(IA)策略.最后,对跳频频谱共享方案的性能进行了分析,基于干扰计算模型得到的仿真结果表明该方案具有较好的IA性能. 相似文献
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针对激光多普勒信号中存在较大噪声干扰的实际情况,为了抑制这些噪声干扰,提高激光多普勒测速仪的测量精度,提出了对激光多普勒信号进行最小均方差(LMS)自适应滤波后作快速傅里叶变换(FFT),基于混合编程思想对所得到的频谱,先进行频谱细化,再进行频谱校正的信号处理方法,并对理想正弦信号和实测多普勒信号分别进行仿真计算和实验研究。仿真和实验结果表明:LMS自适应滤波技术可以有效抑制激光多普勒测量中的多频率噪声的干扰,此技术能够适应于很宽的信噪比范围,大大提高多普勒信号的信噪比;频谱细化技术可以提高激光多普勒信号的频谱分辨率,频谱校正技术可以准确地校正多普勒频率,使校正后的频率更加接近于真实值;信号处理精度比直接进行FFT提高2~3倍。 相似文献
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In this article, the capacity of wireless multi-hop networks with the frequency hopping (FH) technique is derived. Different from the previous work based on non- spread spectrum (SS) system, this study is based on frequency hopping spread spectrum (FHSS) and the retransmission mechanism. The analysis results show that the normalized transport capacity decreases as 1/(Mλ) , when the total available frequency band is divided into M sub-bands for frequency hopping and the nodes are randomly distributed in space according to a Poisson point process with intensity λ . In this work, the best transmission range per hop to get the maximum capacity is also derived. Besides, the results summarize how the capacity of FH wireless multihop networks is affected by the outage probability, target signal to interference plus noise ratio (SINR) and other system parameters. 相似文献
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This paper investigates the impact of the lung-thorax and heart-valve system on the overall spectral composition of the externally recorded heart sounds. The study concentrates on the case of the first and the second heart sounds for normal patients and patients before and after implantation of a mechanical valve in the mitral or aortic position. The analysis is performed using a modified forward-backward overdetermined Prony's method (MFBPM) which uses a forward-backward mean filter and a modified procedure for estimating the position of the signal poles. In terms of the normalized cross-correlation coefficient, this method has an average modeling accuracy of 99.62% for representing the first and second heart sounds and an average least square time-domain error of 0.43%. Results obtained from 40 subjects show that the condition of the native mitral or aortic valve affects mostly the distribution of the amplitudes of the spectral components, whereas the number of the spectral components or their respective relative energy remains more or less unchanged. It has been found that the amplitudes of frequency components in the range 120-250 Hz are more affected by abnormalities of native mitral valves. Furthermore, in the case of the second heart sound the region 250-400 Hz has been found to be more affected by abnormalities in the aortic valve. It has also been found that the mechanical prosthetic heart valve affects mostly the spectrum beyond 400 Hz. A clear difference has been observed in the frequency spectrum above 400 Hz between both normally and abnormally functioning native valves and normally functioning mechanical valves. Preliminary results in some malfunctioning cases of mechanical prosthesis suggest that spectral components beyond 400 Hz can be used to monitor the condition of these prostheses 相似文献
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基于最佳接收和最大化利用现有空闲频谱资源的思想,提出一种认知跳频系统的实现方案,然后在此基础上,重点对其在单频、多频和部分频带干扰下的抗干扰性能进行了研究.理论分析和仿真结果表明,在理想同步情况下,该认知跳频系统较常规跳频有更强的抗干扰能力. 相似文献
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本文以临清市自来水厂为例,设计了一套城市供水控制系统方案。系统集通信、网络、现场总线、PLC、计算机、微波通讯及自动化、远程控制等诸多先进技术于一体,充分体现了现代信息技术和自动化技术在城市供水系统中的应用。尤其详细介绍了变频器在系统中的应用。 相似文献
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This article describes the technical challenges that have to be met when implementing the interesting new technology of spectrum pooling. This notion represents the coexistence of two mobile radio systems within the same frequency range. It enables the secondary utilization of already licensed frequency bands as aimed at by several regulatory authorities worldwide. The goal of spectrum pooling is to enhance spectral efficiency by overlaying a new mobile radio system on an existing one without requiring any changes to the actual licensed system. Several demanding tasks originate from this idea. Some of them have been solved in recent research projects. Others are subject to ongoing investigations. Here, the state of the art in spectrum pooling is presented. 相似文献