第一、三区卫星广播重新规划(上)

本文介绍了广播卫星规划的发展过程，以及２０００年无线电大会通过的卫星广播重新规划的基本原则与技术参数，重点介绍了中国卫星广播规划资源及其最新规划结果。     

12GHz卫星广播规划,现状和前景

本文简介了ＷＡＲＣ－７７ １２ＧＨｚ卫星广播规划的历史背景、主要结果和实施状况，以及提出修订ＷＡＲＣ－７７规划的政治环境变化和技术进展因素。介绍了ＷＲＣ－９５提出的修订规划原则和技术参数。指出各国已提出的新增需求量太大，远超过可能挖掘出来的轨道位置和频谱潜力。预计随着多节目数字电视卫星广播的发展，１２ＧＨｚ卫星广播轨道位置和频谱之争，将日趋剧烈。     

国际电联规划中国广播卫星业务概况

国际电联于2000年5月8日至6月2日在土耳其召开了世界无线电通信大会(WRC-2000)。会上对一、三区卫星广播业务(BBS)重新进行了规划，审议并修改了有关BSS法规条款和技术标准。在新的规划中，中国有4个规划轨位，每个轨位2个下行波束，2个上行波束，每个波束12个频道，共计96个模拟频道，使用单圆极化。与原规划相比，调整和优化了轨道位置，扩大了上、下行波束，使总的模拟频道数由原59个增加到96个，业务区内每个地方可收看的电视频道数由原来的4个增加到现在的12个，     

水利部动图卫星广播系统(下)

四、关键技术 1.卫星IP广播 IP多播是指IP报文向一个“主机组”的传送，这个主机组由一个单独的IP地址标识，也称为“组播地址”。除了目的地址部分，组播报文与普通报文没有区别，网络尽力传送组播报文但是并不保证一定送达。     

美国直播卫星(DBS)发展综述

国际电联(ITU)于1963年将固定业务(FSS)和卫星广播业务(BSS)进行了区分,定义为不同的无线业务。1971年,ITU为FSS和BSS分配了特定的频段。根据当时的技术状况,FSS被定义相对较大尺寸地面固定终端的、所有类型的卫星通信。BSS则被定义为从中心终端设备向相对较小尺寸的社区或家庭接收终端进行传输的卫星通信。后者所     

国际数字卫星直播业务的最新发展(三)

在此仅介绍与我国卫星广播规划轨位(92．2E,134E)相邻或同轨的两颗卫星。     

DOCSIS3.0——第三代电缆数据传输系统(17)

第七章频道捆绑频道捆绑定义为:是对DOCSIS业务流的一种信息调度,该业务流同时涉及多个频道。在下行方向,CMTS分配一个个数据包至多个频道中,通常包括一个下行业务扩展标头,标头中有一个数据包序列号,     

国际数字卫星直播业务的最新发展(一)

本文跟踪研究了国际上卫星数字电视直播和卫星数字声音直播的发展及现状,以及卫星传输标准的最新发展。     

中央及部分省(区、市)卫星广播电视技术参数

中央及部分省(区、市)卫星广播电视技术参数     

Satellite Beam Optimization for the Broadcasting Satellite Service

In view of the forthcoming ITU Regional Administrative Radio Conference for the planning of the Broadcasting Satellite Service at 12 GHz for the American Continent to be held in 1983, there is a need for a means to transfer the service quality requirements for a Broadcasting Satellite Service into a consistent set of satellite and receiving terminal parameters.     

卫星多媒体数据广播业务分析及实现

首先简要分析了卫星多媒体数据广播业务的市场及其应用环境，接下来介绍了其技术和商业特点、实现的方法，最后阐述了卫星多媒体数据广播的市场策略及其相关的资金投入与成本牧益。在介绍卫星多媒体数据广播业务的实现方法时，具体说明了卫星多媒体广播的价值链、平台的功能要求、内容的创建以及技术平台的实现等。     

我国新一代卫星广播系统——先进卫星广播系统(ABS-S)

本文介绍我国新一代卫星直播系统,即先进卫星广播系统(ABS-S).该系统具有的系统性能及提供的业务完全适合未来卫星广播的各种需求.本文分析ABS-S的基本特征及系统性能,基于试验室及现场测试数据,证明了ABS-S系统的先进性.ABS-S系统明显优于目前广泛使用的卫星电视广播标准DVB-S,同时和第二代直播卫星电视广播标准DVB-S2相比,具有等同的性能,且具有更低的系统实现复杂度.最后,介绍了ABS-S系统的产业化推进及应用情况.     

Satellite Sound Broadcasting Around 1 GHz

This paper presents the technical factors affecting the design of a geostationary satellite sound broadcasting system operating around 1 GHz to serve low-cost consumer-quality portable and automobile receivers. The technical characteristics for such a system are under study in a number of countries in preparation for the 1985/1988 ITU Space Services Planning Conference.The first session will make appropriate recommendations to the second session on the future regulatory provisions for the service. A medium-quality monophonic or stereophonic service would be provided using frequency modulation. Signals would be received using a simple circularly polarized omnidirectional antenna. Link margins to serve indoor portable receivers and automobile receivers in rural and urban areas are discussed. Building penetration loss for single family dwellings is expected to be about 11.8 dB in 90 percent of the houses not using foil-backed insulation or shadowed by trees, increasing to over 17 dB with foil-backed insulation. Shadowing by trees increases the loss by 12-15 dB. Apartment and commercial building penetration loss is expected to approach 20 dB. Automobile reception in rural areas will be primarily affected by foliage attenuation due to trees. At a 30° elevation angle, an attenuation of about 15 dB with probability of 0.90 is expected. In situations where the line-of-sight path is unobstructed, multipath fading of 2.8 dB at 0.90 probability is the predominant source of degradation. Automobile reception in urban areas requires operating margins of 24-30 dB because of shadowing and multipath by large buildings. Based on the foregoing considerations, an e.i.r.p. from 66 to 79 dBW is required from a geostationary satellite to serve low-cost portable and automobile receivers in rural and urban environments.     

Transmission System for the Television Broadcasting Satellite

Standardization of transmission system for television satellite broadcasting with multiple sound and/or data signals for an operational broadcasting satellite system is under study in Japan. Based upon result obtained from the BSE experiment, several transmission systems have been developed at the NHK (Japan Broadcasting Corporation).     

Channel Modeling for Multiple Satellite Broadcasting Systems

In this contribution we present the results of a study on land mobile satellite channel models for satellite systems with multiple satellites. The slow fading of our channel model for several satellites is based on a Markov channel state model for joint processes while the Probability Density Function (PDF) of the signal amplitude within each state is fitted to the Loo distribution. The correlation between two satellite channels and the channel spatial autocorrelation have also been studied. We show that a channel state model that uses a Markov state model of order one or of a fixed higher order is not appropriate if the state duration is of very high importance, which can be the case in the process of system planning. Therefore, we propose a dynamic higher order Markov state model for joint processes that depends on the current state duration. This approach models precisely any PDF of the channel state duration for both single and multiple satellite broadcasting systems while having a significantly lower computational complexity than a fixed higher order Markov model. It models the channel states of the whole system correctly, as well as the channel states of each satellite observed independently. It is able to capture the state correlation between multiple satellites. We also study possible approximations of the proposed models in order to reduce their computational complexity while having a good PDF match. Our channel state models are validated by measurements.      

广播电视卫星上行站的系统维护

本文从实际维护需要和可行性出发,着眼于系统维护,介绍了广播电视卫星上行站供电、节目源引接、中频、射频、高功放、天馈线等分系统及整个上行系统的技术维护,希望有益于广播电视卫星上行站科学维护工作的推进。