共查询到18条相似文献,搜索用时 109 毫秒
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随着对地观测技术的快速发展,遥感卫星空间分辨力的不断提高,星地链路传输的信息量越来越大,码速率越来越高,数据传输频段已经由传统的X频段扩展到Ka频段,以满足海量遥感数据传输的需求。但Ka频段低轨遥感卫星波束非常窄,遥感卫星地面接收系统需要具备良好的跟踪性能,才能实现系统稳定的捕获跟踪,保证接收数据的质量。文中通过对跟踪方式和跟踪精确度方面进行分析和论证,优化捕获跟踪流程,实现对低轨遥感卫星Ka频段的捕获跟踪。文中提出利用S频段跟踪引导Ka频段跟踪的方式,高低仰角采用不同的优化流程设计,结合高分辨力对地观测系统重大专项的先期研究内容和某地面接收站进行了设计验证,结果表明,可实现低轨遥感卫星Ka频段的捕获跟踪,待时机成熟,可进行工程应用。 相似文献
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分析了S/Ka频段测控通信系统的组成、运行模式、天/地基测控体制兼容性设计,讨论了窄波束天线的角捕获与跟踪、Ka频段信道及功放、高速调制解调、跳/扩频测控等关键技术,并给出了解决措施.分析计算和实物测试的结果证明系统设计方案有效可行. 相似文献
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针对极化干扰对星地数据传输系统的影响,归纳影响极化干扰的主要因素,推导星地数据传输系统极化干扰的理论模型,仿真数据传输系统在不同的调制体制和信道编码方式下的误码率恶化情况,比较在相同程度的极化干扰下各体制传输性能试验结果,分析在不同的Eb/N0工作门限下,星地遥感数据传输系统所受极化干扰影响的规律。 相似文献
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X/Ka频段遥感卫星地面接收信道便携式测试系统设计 总被引:1,自引:0,他引:1
为解决X/Ka信道在建设和运行维护过程中测试设备笨重、功能单一、设备操作复杂、工作状态无法获取等弊端,通过优化中频与射频链路方案、小型化与多功能集成设计、集中监控与射频线缆供电等方式,设计了一种便携式X/Ka频段遥感卫星接收信道测试系统,实现了1 GHz宽带X/Ka卫星数据地面接收系统射频(7.9~8.9 GHz、18~20 GHz、25~27.5 GHz 3个频段,有线或无线)、中频环路的调试和测试(1.2 GHz、1.5 GHz 2个频段)及信道的测试系统的集中监控、高阶调制、多种编码、多普勒仿真、噪声源添加等功能,极大地方便了现场或野外测试应用。 相似文献
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近年来,宽带、传输流量不对称的多媒体卫星系统的开发和应用,成为卫星通信的热点技术之一。介绍了一种Ka/Ku频段多媒体卫星系统的设计方案,描述了该系统的构成、应用,并对所涉及的调制解调、多址访问、网络接入、安全保密等关键技术进行了讨论。 相似文献
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基于ARM与μC/OS-Ⅱ的GPRS数据终端 总被引:2,自引:2,他引:0
本文根据工业系统的需求,提出了一种结合嵌入式技术和GPRS无线通信技术的远程数据传输终端方案。该终端以ARMS3C44B0X微处理器为硬件平台,以μC/OS-Ⅱ为操作系统,采用了μC/OS-Ⅱ的多任务的软件设计方法,提高了系统的实时性和可靠性。该终端内嵌TCP/IP协议,可以通过GPRS网络连接到互联网,数据传输实时性强,为用户提供透明的数据传输通道。最终在实验室环境下进行了测试,达到了预期透明传输数据的目标。 相似文献
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文章介绍了LTE网络接口(S1/X2接口)的测试规范以及协议一致性测试的基本模型,并针对一致性测试的关键技术进行了具体的分析和研究,能够为今后S1/X2接口标准化评估提供重要参考,具有一定的工程应用价值。 相似文献
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主要探讨Ka频段抗干扰卫星通信系统地球站射频单元的几项关键性技术,首先,简介Ka频段抗干扰卫星通信系统的特点及国内外Ka频段射频技术研究现状和发展方向,进而讨论一种Ka频段抗干扰卫星通信地球站射频单元的主要研究内容和主要电性能指标,最后给出其几项关键技术的解决方法。 相似文献
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Tsutaki K. Seura R. Fujiwara E. Tomikawa K. 《Electron Devices, IEEE Transactions on》2005,52(5):660-664
Various types of millimeter-wave radio systems are being developed for strong broadband service demands such as fixed wireless access, local multipoint distribution service, as well as satellite communications. In each system, the higher data rate transmission requires more powerful amplification devices. This paper describes the development of a Ka-band 100-W peak power millimeter-wave power module, traveling wave tube-based millimeter-wave amplification module, used for millimeter-wave fixed wireless access base stations and Ka-band satellite Internet terminals. 相似文献
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针对天地一体化信息网络中星地间高速、高效数据自适应传输需求,在宽带卫星通信 DVB_S2X 标准的基础之上,开展高效自适应传输控制技术研究,包括高精度信道估计、低延时信道状态预测与自适应编码调制选择切换策略等关键技术,满足自适应编码调制技术(ACM) 的使用要求。并完成典型模拟环境下高效自适应传输控制技术的测试验证,为后续宽带通信卫星系统、星地高速数据传输系统以及天地一体化信息网络的构建奠定技术基础。实验结果表明,该方法可以在不同信道条件下都保持最大的传输效能,大幅度提高系统的频谱效率和数据吞吐量。 相似文献
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Hughes C.D. Soprano C. Feliciani F. Tomlinson M. 《Electronics & Communication Engineering Journal》1993,5(5):285-291
The next generation of satellites is discussed and a Ka-band payload is proposed which will provide mesh connectivity at high data rates (e.g. 1 Mbit/s) directly between very small aperture terminals (VSATs) using a maximum antenna diameter of 1.5 m. It is demonstrated that there are no significant differences between Ku-band and Ka-band VSAT operations apart from propagation margins, which are analysed statistically over 650 European cities. It is shown that margins required for Ka-band operation are not excessive. A Ka-band satellite payload is proposed, based on frequency division multiple access, multibeam switching with dynamically controllable transponder bandwidths and gain. The payload adapts to traffic-loading requirements in its provision of multibeam connectivity and capacity. The signal format, modulation and coding technique used for transmission is unconstrained, except in terms of bandwidth, and this will allow advances in modulation and coding to take place during the lifetime of the satellite in orbit 相似文献
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Traffic management for TCP/IP over satellite ATM networks 总被引:1,自引:0,他引:1
Goyal R. Jain R. Goyal M. Fahmy S. Vandalore B. Kota S. 《Communications Magazine, IEEE》1999,37(3):56-61
Several Ka-band satellite systems have been proposed that will use ATM technology to seamlessly transport Internet traffic. The ATM UBR, GFR, and ABR service categories have been designed for data. However, several studies have reported poor TCP performance over satellite ATM networks. We describe techniques to improve TCP performance over satellite ATM networks. We first discuss the various design options available for TCP end systems, IP-ATM edge devices, as well as ATM switches for long-latency connections. We discuss buffer management policies, guaranteed rate services, and the virtual source/virtual destination option in ATM. We present a comparison of ATM service categories for TCP transport over satellite links. The main goal of this article is to discuss design and performance issues for the transport of TCP over UBR, GFR, and ABR services for satellite ATM networks 相似文献
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Hongrong Shen Qian Ning Bingcai Chen 《International Journal of Satellite Communications and Networking》2023,41(4):406-425
To address the problem that Ka-band satellite communication signal transmission is easily affected by rainfall and terminal environment, combining the characteristics of high-speed movement of LEO satellites and the wave propagation characteristics of satellite-ground links, this paper establishes a Markov synthesis model of four-state satellite channels based on Ka-band that integrates rainfall attenuation and terminal shadow attenuation, and a scheme for adaptive coding and modulation selection based on the DVB-S2 standard is proposed. Based on this, a rainfall fading probability density function (PDF) based on the satellite elevation angle variation is derived, and a more efficient and streamlined set of modulation and coding(MODCOD) is obtained through simulations and calculations. The simulation results show that the proposed scheme not only effectively solves the problem of severe fading of the transmission signal due to rainfall, ground movement environment and satellite mobility but also significantly reduces the system complexity of the original DVB-S2 standard scheme with little loss of efficiency. 相似文献