地空雨衰减预报新模式比较

地空雨衰减预报模式一直是10GHz以上频段地空传播特性研究的重点,2003年中国和英国分别向ITU-R提交了两种地空雨衰减预报改进模式.本文介绍了其改进之处,并按ITU-R的要求,对这两种新模式进行了比较,比较结果表明中国模式具有更好的预测精度.     

雨衰减的解析近似

本文对Ｌａｗｓ－Ｐａｒｓｏｎｓ和广州雨滴尺寸分布雨衰减和降雨经之间的指数关系中的ａ和ｂ值＾「１」「２」进行了分析和解析回归，给出其与频率的解析近似关系，利用其计算的雨衰减和数值计算结果有很好的一致性。     

中国Ku波段广播通信卫星雨衰减分布

雨衰减对于１０ＧＨｚ以上无线电系统的影响是极为严重的。本文根据我国６５个站点的分钟降雨率数据，利用ＩＴＵ－Ｒ最新给出的雨衰减预报模式，计算出我国未来１２ＧＨｚ三个轨道     

基于进化神经网络的地空路径雨衰减模型

雨衰减对工作在高频的地空通信链路稳定性具有很大影响。本文在考虑多个参数对雨衰减非线性影响的基础上,建立了基于进化神经网络的雨衰模型,并与ITU－R模型进行了比较。结果表明,利用本文提出的模型进行高频电波的预测具有更好的精度,可降低平均误差0.64dB,并减小标准偏差0.79bD,为雨衰减预测提供了一种新的方法。     

由实测小时雨量预报地星通信雨致衰减的方法研究

利用１９９１年中国３３３个地面雨量站的小时雨量数据，进行降雨率累积概率对数正态和伽玛分蝗计算比较，得出伽玛分布在较大的降雨范围内能更好地反映实际降雨率累积概率分布。     

On the rain attenuation dynamics: spatial‐temporal analysis of rainfall rate and fade duration statistics

Knowledge about the dynamic characteristics of rain attenuation is of utmost importance for many applications in terrestrial and satellite communication systems operating at frequencies above 10 GHz. Long‐term rain rate statistics and rain rate duration statistics are usually available from meteorological data. In this paper, a spatial–temporal analysis is employed in order to evaluate the rain attenuation power spectrum of a terrestrial/satellite path. The predicted power spectrum is compared with experimental data. Based on the spectral analysis of rainfall rate a method for converting rain rate duration statistics to link fade duration statistics is also proposed. Fade duration statistics are presented for terrestrial and satellite links and compared with available experimental data. The agreement between the predicted results and the experimental data has been found to be quite encouraging. Finally, numerical results are presented for various climatic zones, elevation angles and frequencies. Some very useful conclusions concerning the dynamic properties of rain attenuation for a microwave path are deduced. Copyright © 2003 John Wiley & Sons, Ltd.     

雨衰减预测中的降雨率调整因子概念

利用ITUR数据库地面视距链路和地空链路雨衰减数据,分析了传统雨衰减预报中所使用的基于柱状雨胞模型的雨衰减物理模型导出的路径调整因子与实测数据之间的矛盾.在此基础上,基于指数雨胞建立的雨衰减物理模型,通过理论分析导出了降雨率调整因子的概念.利用降雨率调整因子,可以解释实测数据的主要特征,表明：基于指数雨胞的雨衰减物理模型是合理的,利用降雨率调整因子的概念,可为发展新的地面视距链路和地空链路雨衰减预报模式和方法提供理论依据.     

Microwave depolarization versus rain attenuation on earth space in Malaysia

The wave propagation experiments using Japanese geostationary satellite Superbird‐C have been performed at the Universiti Sains Malaysia earth station. A relationship between rain depolarization and attenuation, valid for earth‐space path at microwave wavelengths, is presented. Cumulative rain attenuation and cross‐polarization discrimination (XPD) statistics are given for the period of 4 years (2002–2005) at 12.255 GHz. XPD varied from 44 dB at 1% to 16 dB at 0.001% of time the abscissa is exceeded. Comparisons were made with available data sets and with five simple XPD models and the results indicate a good performance by the simple isolation model and the CHU model compared with the others. These results serve as checks on the theoretical models needed for predicting communication system performance in geographical regions especially for equatorial climate where measurements are not available. Copyright © 2008 John Wiley & Sons, Ltd.     

中国Ka波段卫星通信线路的雨衰分布特性

利用ITU-R给出的降雨衰减预测模型,根据我国主要城市的分钟降雨率数据,计算出我国Ka波段(30/20GHz),轨道位置为92°E的卫星通信系统在线极化波情况下的降雨衰减等值线分布,此结果可作为Ka波段卫星通信系统设计的理论依据。     

一种地面视距链路雨衰减预测模式

基于指数雨胞雨衰减物理模型得到的降雨率调整因子概念,通过对ITUR雨衰减数据库实验数据的分析,提出了一种降雨率调整因子公式,并利用ITUR雨衰减数据库数据回归得到了降雨率调整因子公式的参数,建立了一种利用全概率降雨分布的地面视距链路雨衰减预测模式通过与其它模式的比较表明：该模式预测精度优于其它利用全概率降雨的雨衰减预测模式,预测精度与利用概率转换的ITUR模式相当,且预测过程更加简便。     

Diurnal variations in rain attenuation on Ku band earth–space paths

This paper presents analytical results of the diurnal variations in Ku band rain attenuation along earth–space paths at four locations in Southeast Asia and proposes a new model that can predict rain fade in a short period of every 2 h daily. Data from four radiometers and four rain gauges over a 3 year period were analysed to obtain the characteristics of diurnal variations in rain attenuation and rainfall as well as cumulative attenuation distributions in every 2 h interval. The results of this analysis are applied to develop an intensive prediction model using the knowledge of rainfall and attenuation statistics. This model is tested with the measured data and is found to be useful for the design of a more efficient Ku band satellite system especially between 99 per cent and 99·9 per cent link availability in an area of heavy rainfall. © 1998 John Wiley & Sons, Ltd.     

视距链路的雨衰减预报模式研究

基于ITU-R的视距链路雨衰减数据库中的数据,本文提出了一种新的视距链路雨衰减的预报模式,给出了一种新的路径调整因子与不同时间概率雨衰减转换公式.与其他几种预报模式的比较表明,新模式与实验结果有更好的一致性.     

基于雨胞分布的视距链路雨衰减预报模型

基于指数雨胞分布,推导得到路径调整因子,提出了一种新的视距链路雨衰减预报模型.利用ITU-R视距链路雨衰减数据库数据回归得到了预报模型中的参数.通过和ITU-R模型以及近几年发展的几种雨衰减模型比较表明,这一模型较其他模型具有更好的预测精度.     

Ka卫星通信系统中雨衰分析

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。     

Modelling of short‐term frequency scaling for rain attenuation using ITALSAT data

In this article we describe a statistical model for the assessment of the short‐term frequency scaling ratio between rain attenuations at cm and mm wavelengths, taking into consideration the fluctuations arising from the type of rain (mainly the raindrop size distribution). The model has been derived from measured data, using the large attenuation database collected in Spino d'Adda, Italy, during the ITALSAT 8‐years experiment at 18.7, 39.6 and 49.5 GHz, but can be applied to any pair of frequencies. By applying the model it is possible to generate, by means of a generator of random Gaussian numbers, samples of the up‐link attenuation, for a given down link attenuation, to be employed in the simulation of up‐link power control (ULPC) slant path channels. Copyright © 2006 John Wiley & Sons, Ltd.