亚运会转播国际声采集和传输系统

以广州亚运会为背景,概括地叙述了大型体育赛事转播系统中,国际声信号的采集和制作所遵从的原则及具体方法,并给出了高质量的、可靠的传输方案。     

地面数字电视单载波系统如何实现移动接收

结合2001年春的私人讨论,介绍了单载波系统实现移动电视接收的关键技术:考虑非专家的主观判据,在系统设计中缩小数据结构;在解调器中,采用过采样相位跟踪技术,合理利用回波或多径信号的能量,并采用非线性处理替代线性处理;对现场测试中实验方法的建议.这些技术的综合应用,不仅在原理上解决了采用单载波系统实现移动电视接收的国际难题,还解决了用单载波技术组建单频网以及固定接收中单载波与多载波如何处置复杂的动态回波的难题.     

CA系统中基于用户分组的EMM分发机制

提出了一种新颖的用户分组机制以降低条件接收系统的复杂度.与传统密钥分发机制相比,该方案在保证系统安全性并实现条件接收系统功能的前提下,大大减少了系统中授权管理信息的数据量,提高了系统的业务管理效率.     

中国西北地区沙尘暴的发生规律研究

借助MATLAB软件,根据中国西北地区六个省份1981～2005年沙尘暴发生天数、月平均风速、大风发生天数、月平均气温、月降水量、月平均相对湿度的统计数据,研究中国西北地区沙尘暴的区域分布和时间分布规律及其与气象因子的关系.方差分析结果表明:西北地区沙尘暴危害程度省份差异不显著,不同观测站所在地沙尘暴危害程度的差异显著,不同月份沙尘暴危害程度的差异也显著;聚类分析结果表明:拐子湖等站点所在地受沙尘暴危害最严重,各年4月份受沙尘暴危害最严重,北京地区8月份几乎不发生沙尘暴;相关分析结果表明:西北地区沙尘暴的气候影响因子为月平均风速、月大风发生天数和月相对湿度.由回归分析得到,沙尘暴每月发生天数y随月份t的变化规律为正态分布.研究结果可供有关部门参考.     

电视播控管理系统的设计与开发

从播控管理系统的需求分析入手,构建了系统各功能模块,建立数据库,对系统登录、用户权限管理、播控资源管理等模块做了分析与设计。系统对播控信息数据进行统一管理,完成了信息的收集、统计、汇总和分析等功能,实现了对电视播控事务科学、高效的管理。     

Response Time in Data Broadcast Systems: Mean,Variance and Tradeoff

Data broadcast has been suggested as a promising method of information dissemination [2,33]. In such an environment, the information server cannot afford to serve the requests from a large population of users individually. Instead, the server uses a broadcast channel to deliver information to all users. A single transmission of a data item satisfies all pending requests for that item. The response time of a request depends on the broadcast time of the desired data item, which is scheduled by the server according to the overall demands for various data items. Therefore, the response time may vary in a large range. We argue that, in addition to mean response time, the variance of response time should also be taken into account by the broadcast scheduler. In this paper, we address the issue of variance optimization in regard to response time. Building on our previous research on mean response time optimization, we propose an algorithm which can minimize the variance of response time. Furthermore, we evaluate an algorithm that facilitates a tradeoff between the mean and variance of response time. Numerical examples that illustrate the performance of our algorithms are also presented.     

调幅广播附加信息的传输

在调幅声音广播中,除了传送正常的广播节目外,还可兼容传送其它附加信息,提供新的服务。本文综述了近年来国外这项技术的研究发展概况,介绍了传送附加信息的方法、基本原理及应用,并讨论了其它有关问题。     

一次强沙尘暴长距离输送的数值模拟研究

利用HYSPLIT-4传输,扩散模式对2003年4月9日发生在我国西北的强沙尘暴进行长距离输送的数值模拟研究,并进行轨迹和浓度分析.研究结果表明:(1)2003年4月9日强沙尘暴过程的沙尘来源并非某单一地区;(2)此次沙尘暴长距离输送过程中,主要有两个高浓度中心向东传输.一个在北纬35度附近,主要在1 500～3000m高空传输,另一个在北纬40度附近,且主要在1 500m以下传输.后期两者合二为一.     

无线电数据系统

欧广联(EBU)的无线电数据系统(RDS),是为在FM立体声广播中兼容传输附加信息而设计的。本文介绍了RDS的研究、发展与应用概况,阐述了RDS信号的产生、可传输的信息及其编码方法、数据格式和RDS接收机。     

Compressive image broadcasting in MIMO systems with receiver antenna heterogeneity

In this work we consider image delivery in MIMO broadcast networks with diverse channel quality and varying numbers of antennas across receivers. In such systems, performance is normally constrained by the weakest users with either a low channel SNR or only a single receive antenna. To address both dimensions of heterogeneity, we propose a new analog image delivery system that adapts seamlessly along both dimensions simultaneously. Our sender scales the DWT coefficients according to a power allocation strategy, and generates linear combinations of the coefficients using compressive sensing (CS), before transmitting them with amplitude modulation. On the receiving side, the received physical layer symbols are passed directly to the source decoder without conventional MIMO decoding, and the DWT coefficients are recovered using a CS decoder.There are two main contributions of our system. First, integrating CS into MIMO transmission ensures that the reconstructed image quality at the receivers is commensurate with both the channel SNR and the MIMO channel dimension. Second, we introduce a power allocation strategy to achieve a performance tradeoff between receivers with different antenna numbers. Experimental results show that the proposed system outperforms both the analog reference SoftCast and the conventional digital system known as HM-STBC. The average gain is 2.92 dB over SoftCast for single-antenna users and 1.53 dB over HM-STBC for two-antenna users.