共查询到18条相似文献,搜索用时 437 毫秒
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Ka频段卫星通信中,降雨引起的信号衰减对通信链路的通断起着非常重要的作用。本文详尽分析了Ka频段卫星通信信道的电波传播特性,重点分析了降雨对卫星通信的影响,并提出了Ka频段抗雨衰的各种对策。 相似文献
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本文首先介绍了Ka频段卫星通信雨衰产生机理及ITU-R雨衰预测模型。然后重点介绍了103°E在轨Ka卫星在我国各雨域地区(典型城市)的雨衰情况。最后联系以往Ku频段工程实施经验,总结出常用的三种Ka频段卫星通信抗雨衰补偿方法:分集技术中的业务速率分集技术、功率控制技术中的上行链路开环功率控制技术和自适应编码技术中的自适应纠错编码技术。 相似文献
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Ka频段的抗雨衰对策 总被引:4,自引:0,他引:4
Ka频段卫星通信系统具有广阔的应用前景,该文从Ka频段雨衰的特点以及卫星通信系统上下行链路的不同特点出发,提出了自适应抗雨衰对策。详细分析了自适应杭雨衰对策的实现原理及算法,分析得出:上行链路采用自适应功率控制,下行链路采用自适应纠错编码是解决ka频段的雨衰问题的有效方法。 相似文献
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随着Ka频段卫星通信产品的推广应用,降雨衰减在卫星通信系统中的影响越来越大。经典雨衰预测方法利用年固定时间百分比降雨率数据计算,在卫星通信系统设计中发挥了重要作用,但并不能用于天气对全网各节点的影响分析。随着气象科技的不断进步,小时降水量预报不断精细,使得在特定通信保障任务中评估预测各节点雨衰值成为可能。在充分介绍了经典雨衰模型ITU-R和数值天气预报的基础上,从降雨率换算、降雨率平均化、雨顶高度判定三个角度出发,提出了构建基于降水预报数据雨衰预报模型的关键问题,并指出了相关改进方法。 相似文献
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毫米波卫星通信及抗雨衰技术 总被引:2,自引:0,他引:2
卫星通信经过几十年的发展巳成为现代强有力的通信手段之一,但随着现代多媒体通信和个人通信的高速发展,低频段的卫星通信巳不能满足现代通信宽带的要求,使用更高频段的毫米波是卫星通信发展的必然趋势。毫米波卫星通信具有带宽大、干扰小等特点,但由于降雨衰减较大,研究毫米波卫星通信的抗雨衰技术成为卫星通信技术研究的热点。我国应密切注意卫星通信发展的最新趋势,加大力度进行高频段卫星通信系统的研究和开发。 相似文献
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Ka频段卫星通信分集和自适应抗雨衰技术 总被引:1,自引:0,他引:1
Ka频段卫星通信的抗雨衰技术能够有效降低Ka频段的雨衰影响,提高Ka频段信号
传输质量。重点讨论了分集技术和自适应技术,综述了现有的抗雨衰技术及其之
间的联系,总结了热点研究方向,为今后抗雨衰技术的研究奠定了基础。 相似文献
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简单介绍了雨衰的机理,并以我国原邮电部给出的雨衰模型为基础,根据我国10个主要城市的降雨数据和地理位置参数,计算出轨道位置在80°E的通信卫星在上行水平极化/下行垂直线极化的情况下,Ka波段(30/20GHz)的雨衰A0.01,并就雨衰对下行卫星链路G/T值恶化带来的影响进行了分析讨论,给出了相应的计算方法,最后总结了几种抗雨衰措施。 相似文献
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在Ka及以上高频段卫星通信系统中,其链路信号的衰减很严重,主要是大气、降雨、闪烁对卫星信道的影响。本文主要研究了雨衰和对流层闪烁产生衰减的机理与特性,提出雨衰采用DAH模型,闪烁采用Van de Kamp模型。然后根据实测气象数据,计算我国各参考站点的雨衰和闪烁值。为抗衰减对策的提出提供理论依据,为工程设计提供具体的参考数据。 相似文献
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Khairayu Badron Ahmad Fadzil Ismail Md Rafiqul Islam Khaizuran Abdullah Jafri Din Abdul Rahman Tharek 《International Journal of Satellite Communications and Networking》2015,33(1):57-67
Radio wave propagation plays a very important part in the design and eventually dictates performance of space communication systems. Over time, the requirements of satellite communication have grown extensively where higher capacity communications systems are needed. Escalating demands of microwave and millimetre wave communications are causing frequency spectrum congestion. Hence, existing and future satellite system operators are planning to employ frequency bands well above 10 GHz. The challenge in operating at such high frequencies for communication purposes is that there exists stronger electromagnetic interaction between the radio signals and atmospheric hydrometeors. Such instances will degrade the performance of such high frequency satellite communication systems. The development of a revised model for a better‐improved rain fade prediction of signal propagations in tropical region is considered very important. Researchers and engineers can employ the model to accurately plan the future high frequencies satellite services. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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By considering the global fading process on the link caused by rain attenuation and amplitude scintillations, particularly at K a band, it is possible to derive a long-term statistical model of the satellite channel capacity. The four-parameter distribution, which combines amplitude scintillations and rain fade within an up/down link system, is presented. Also presented are the degradation (and improvement) of bit error rate (BER) in the presence of amplitude scintillations, thus complementing the flat fade effect due to rain only. By implementation of adaptive communication systems, a more efficient channel capacity utilization is possible. The concepts and the use of novel analytical expressions combining a log-normal model of rain fade with a Moulsley-Vilar distribution for scintillations are illustrated. These are then applied to a very-small-aperture terminal (VSAT) example of a 29/19-GHz digital communications link through the Olympus satellite using M -ary phase shift keying (PSK) modulation schemes 相似文献
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EDGAR H. SATORIUS LORETTA H. TONG 《International Journal of Satellite Communications and Networking》1996,14(3):297-311
A rain compensation algorithm (RCA) has been developed for use in the advanced communications technology satellite (ACTS) mobile terminal (AMT) system. The basic goal of the RCA is to control the transmitted data rates (9·6, 4·8 or 2·4 kbps) in the forward and return links so that a 3 dB link margin is maintained at the highest possible transmitted data rate. In this paper, analyses of both theoretical and practical issues relating to the RCA are presented. In addition, sample simulations of a one-dimensional version of the RCA at the MT are presented which illustrate typical RCA performance using both simulated and recorded pilot fade field data. It is found that with suitable post-processing, the RCA can provide reasonable (conservative) data rate estimates without making excessive data rate changes, i.e., data rate change fluctuations. It is anticipated that the results presented here will not only be useful for the eventual operation of the RCA, but more generally will be useful in the design and operation of other rain compensation techniques for K/Ka-band communication systems. 相似文献
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Bauer R. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1997,85(6):853-862
The Advanced Communications Technology Satellite (ACTS) was conceived at the National Aeronautics and Space Administration (NASA) as a follow on program to its long history in satellite communications projects that have reduced the risk of developing new technologies that fall outside the sponsorship capability of the private sector. To counter the foreign challenge that developed in the late 1970's to the once insuperable US lead in this field, ACTS was developed to maintain the US preeminence. Launched in September 1993 from the space shuttle, key technologies on ACTS include a multibeam antenna, a baseband processor, a 900 MHz wideband microwave switch matrix, adaptive rain fade compensation techniques, and the use of Ka-band frequencies. Since this is the United States' first effort in using Ka-band for satellite communications, beacons are incorporated on the satellite, which provide an opportunity for propagation measurements. NASA is sponsoring a network of propagation experimenters using these beacons and receive-only terminals identical in design. This paper provides some history that leads to the eventual development of ACTS. Also, a system overview of the spacecraft is provided for those less familiar with it 相似文献