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41.可接收数字广播节目的GSM移动终端的硬件设计,毕业设计

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Digital Audio Broadcasting The description of DAB technology is from the EUREKA 147 project, a cooperative arrangement to develop DAB by the European Broadcasting Union and electronics companies. Although there may be further developments of the technology and, therefore, contenders in the future DAB market, the EUREKA 147 is thus far the only system which has been successfully demonstrated. It is also most certainly the basis for the discussion by the various players in the current policy debate. Sound quality: the sound to noise ratio for DAB will be 90dB compared to 70dB for FM radio. Frequency response for DAB will equal that of CDs at 20Hz to 20kHz compared to the relatively limited range of FM radio at 50Hz to 16kHz. Spectrum efficiency: By using only the sounds that are audible and by eliminating noise allows the signal to be reduced by about 8O7o. The EUREKA 147 system can transmit 16 separate stereo channels in 4MHZ of spectrum. Economically efficiency: Because the signals are interleaved, the transmission facilities would be operated by a consortium for the construction, operation, and maintenance of a common transmission plant. Electrical power conservation and savings also will be a formidable advantage of DAB. Tests of the EUREKA 147 system show that DAB uses at least one-twentieth (some say as high as one-thousandth) the electrical power used by a conventional FM transmitter to cover an equal area. Faithfulness of signal reproduction: DAB receivers will be designed to use reflected signals as alternative sources of information when the primary signal deteriorates. Using smart receivers which correct the fading and interference problems associated with AM and FM broadcasts. Parity among stations and less regulation: Following a complete station migration to a single DAB band, the current distinctions between FM and AM would disappear. Competition between stations could be based on programming rather than technical abilities and advantages. Moreover, technological parity may remove the burden of the technical aspects of radio regulation from the FCCs workload. DAB, as a digitized broadcast radio signal, promises CD quality sound; transmission diversity as either terrestrial or satellite services; signal, spectrum, and economic efficiency; and station parity and less regulation. Of these promises, ntstransmission diversity and station parity are seemingly the most problematic to the currently constricted doctrine of localism. Transmission Diversity: The Question of Satellite DAB The most heated debate to date concerns the effect that DAB will have on the current radio service environment. The word localism is invoked unsparingly in the debate. Those who believe that DAB is a threat to current conditions are primarily concerned with the effects of satellite, superstation DAB services on the advertising base and program content of local radio (i.e., overemphasis of particular formats). The National Association of Broadcasters (NAB), Westinghouse, Pulitzer, Sconnix, and the Tribune Companies (FCC, 1991b) argue that satellite-based DAB services are the greatest threat to localism. All are in agreement that the FCC should ensure the retention of the current level of localism in American radio. The NAB, in arguing that FCC policy should minimize the economic impact of DAB, maintains that satellite DAB would: Affect the amount of advertising placed on local radio stations, and the related cost of air time on the stations rate card. Due to the inherent nonlocal nature of satellite-distributed services, if commercial satellite audio broadcasting services were to be based on advertising, rather than on subscription fees, a substantial percentage of the revenues would likely come from existing national and/or regional advertisers. Consequently, the existing foundations of advertising revenues, supporting local radio services, would be affected, perhaps significantly. (FCC, 1990c). The NAB estimates an immediate loss of revenues at about one fifth of the total economic base of the entire U.S. radio industry, with the heaviest losses felt by AM radio. This figure is based on the total revenues currently received by radio from national and regional advertising, which could possibly shift to satellite based, super-station services, if and when established. They estimate that financial profits for the entire radio industry would drop to zero if less than a third of radios present national/ regional advertising were diverted to satellite-delivered services (FCC, 1990c, p. 15). Of course, all of the arguments made for the maintenance of a terrestrial-only system argue for a market value construct of localism. It is to the advantage of the established broadcasters to support the traditional market construct of localism for economic, as well as political reasons. Economically, they protect their own businesses and market stability. Politically, by supporting the FCCs traditions, the broadcasters confirm the institutional memory of the FCC and their shared past. These conditions support the notion of “ FCC as licenser and political protector of the business.” Indeed, stations (and their right to make money) should be ensured by the FCC in exchange for servicing the local area. ntsIntroduction The new digital radio system DAB (Digital Audio Broadcasting, nowadays often called Digital Radio) is a very innovative and universal multimedia broadcast system which will replace the existing AM and FM audio broadcast services in many parts of the world in the future. It was developed in the 1990s by the Eureka147/DAB project. DAB is very well suited for mobile reception and provides very high robustness against multipath reception. It allows use of single frequency networks (SFNs) for high frequency efficiency. Besides high-quality digital audio services (mono , two-channel or multichannel stereophonic ), DAB is able to transmit programme-associated data and a multiplex of other data services (e.g. travel and traffic information, still and moving pictures, etc.). A dynamic multiplex management on the network side opens up possibilities for flexible programming . In several countries in Europe and overseas broadcast organizations , network providers and receiver manufacturers are going to implement digital broadcasting services using the DAB system in pilot projects and public services . DAB works very differently from conventional broadcasting systems. Most of the system components such as perceptual audio coding ,channel coding and modulation , multiplex management or data transmission protocols are new solutions and typically not so familiar to the expert in existing analogue or digital broadcast systems. System Concept 2.1 The Physical Channel Mobile reception without disturbance was the basic requirement for the development of the DAB system. The special problems of mobile reception are caused by multipath propagation: the electromagnetic wave will be scattered, diffracted, reflected and reaches the antenna in various ways as an incoherent superposition of many signals with different travel times. This leads to an interference pattern that depends on the frequency and the location or for a mobile receiver the time. The mobile receiver moves through an interference pattern that changes within microseconds and that varies over the transmission bandwidth. One says that the mobile radio channel is characterised by time variance and frequency selectivity. The time variance is determined by the vehicle speed n and the wave length c/f0, where f0 is the transmission frequency and c the velocity of light. The relevant physical quantity is the maximum Doppler frequency shift: Table 2.1 shows some practically relevant figures for fDmax. ntsThe actual Doppler shift of a wave with angle a relative to the vector of the speed of the vehicle is given by Audio Services and Applications 3.1 General The DAB system is designed to provide radio services and additional data services. This chapter focuses on the main audio services as the central application. The audio services use MPEG Audio Layer II to provide mono, stereo and multichannel programmes to the listener. Although the first broadcast applications and receivers will only supply stereo programmes, the migration to multichannel services is nevertheless already included in the system. Data services will become more and more important and one can currently see many new ideas on their use being developed and tested. Most advanced is the Internet, but it is easy to envisage that the data capacity of the DAB system can be used for very similar services. This chapter focuses on the main service of DAB the audio broadcasting service and the standard that is being used. We intend to give the reader an understanding of the features of the audio system and the possible pitfalls without going into too many details that the user (content provider, broadcaster and listener) has no influence on. Data Services and Applications 4.1 General While DAB development started mainly focused on audio broadcast, data capabilities have been designed into the system right from the beginning. After successful presentations of the new digital audio broadcast system at the beginning of the 1990s, these data capabilities gained more and more interest and prototype data services were demonstrated by different project partners of Eureka 147 at related events (e.g. at NAB in Las Vegas, Spring 1992). In order to harmonise these prototype data services and to reach compatibility between the equipment and services, data interfaces, protocols and applications were defined to match the needs of broadcasters, service providers and end users. In the meantime it is generally accepted that the usage of some DAB channel capacity, Especially for multimedia data services, is crucial both for user acceptance and for financing of the networks of this new digital broadcast medium. All the necessary hooks are available to follow this route. nts4.2 Data Service Signalling The DAB multiplex is organised into services and service components . Data transmissions can either be a service component of an audio service, e.g. if it carries data which are related to the service, or if there is no relation to a programme service, a data service can be transmitted as a standalone service, and can be made up from one or several data service components. References: 1Edited by Wolfgang Hoeg/Thomas Lauterbach Digital Audio Broadcasting(principles and applications of digital radio) 2003 2ETI 300 401 ETS 300 401 Radio broadcasting systems Digital Audio Broadcasting DAB to mobile portable and fixed receivers May 1997 nts数字音频广播 数字音频广播技术的描述来自于 EUREKA 147 系统，由欧洲广播联盟和各电子公司合作发展数字音频广播。虽然该技术可能有更进一步的发展，但是在竞争激烈的未来数字音频广播市场上， EUREKA 147 系统已经被成功的证明是唯一久远的系统标准。而这无疑也是争论当前政策的各方面人的讨论基础。 声音质量：数字音频广播的信噪比为 90dB 明显优于模拟调频广播的信噪比70dB。而数字音频广播的频率响应范围从 20Hz 到 20kHz 将可以与 CD 机相媲美，相比较之下模拟调频广播的范围相对较局限从 50Hz 到 16kHz。 频谱利用率：在只使用可听得见的声音频率和在允许程度上消除噪声后，信号大约被减弱了 80%。 EUREKA 147 系统在 4MHz 的频谱内可传输 16 个独立的立体声频道。 经济效率：因为信号是“隔行扫描的”，传输设备将被一个使其产构造、运算和维护的公共设备的协会操作。电力能源的保存和节约也将是数字音频广播的一个巨大优势。 EUREKA 147 系统的测试显示，发射覆盖相同的区域的信号数字音频广播发射机所需要的电力是传统的模拟调频广播发射机所消耗电力的二十分之一（也有的说高达一千分之一）。 信号转发的准确性：数字音频 广播接收机将被设计为当主要信号恶化衰减时，可接收使用有选择性来源的转发信号的信息。使用此智能接收机改良了之前模拟调幅广播和模拟调频广播信号容易衰减和受干扰的问题。 基站和较少规章之间的对等性：在独立的数字音频广播频段发射基站移植建设完善后，当前与模拟调频及调幅广播的差别将消失。其基站的竞争重点将放在规划设计上更甚于技术水平和优势上。此外，科技上的对等性可以把无线电技术表面的调整工作量负担从美国通信委员会卸下。 数字音频广播，作为一个数字化广播无线电信号，承诺有着可与 CD 媲美的音质；其传输方式可以是地面或人造 卫星等任一种方式，信号，频谱和经济的效率，地位的对等性和较少的规章。这些承诺中，传输方式的差异和基站对等性对通常有狭隘地方观念的教条学说来说是最明显有疑问的部分。 传输差异：人造卫星发射数字音频广播的一些问题 当前所关注讨论最热烈的是数字音频广播将对当前的广播服务环境造成什么样的影响。“地方主义”这个词在讨论中被保守的调用。那些相信数字音频广播对当前的广播环境是一种威胁的人主要是质疑人造卫星的效果，“超级站”数nts字音频广播服务的广告基础和局部广播的节目内容（也就是说，过分的强调细节形式）。 全国广播 工作者协会（美国， NAB）， 韦斯汀豪斯 , 普利策 , 斯考尼克斯和论坛公司 (美国通信委员会 , 1991b)争论说基于人造卫星的数字音频广播服务对地方主义观念是最大的威胁。所有人都一致认为美国通信委员会应该确保当前地方主义在美国无线电广播标准的保持力。全国广播工作者协会，在讨论说服美国通信委员会的政策应当是要将数字音频广播经济上的冲突和影响最小化，要使人造卫星发射的数字音频广播得以维持应该： 抢占大量地方广播的广告市场和那些有关系的在电视节目开始之前的时间段的站的卡片比率成本。由于人造卫星分区服务固有的非局 部地区的本性，商业的人造卫星音频广播服务 是主要是基于广告收入来维持，更甚于签署协议定金之类的费用来维持，一笔固定百分比的收入将来自于已存在的国家和 /或地区的广告收入。因此，那些已经存在的维持当地广播服务的广告收入基础，将会受到影响，或许是重大的影响。（美国通信委员会， 1990c） 全国广播工作者协会在整个美国无线电通信工业总计经济基础大约五分之一的基础上评估了一项国家收入直接的损失，包括模拟调幅无线电广播这项最严重的损失。这项统计是基于当前国家和地区无线电通信的广告总收入而做出的，这些或许可能转换成以人 造卫星为基础的“超级站”服务在这些建立以后。他们（ NAB）预测说“整个无线电通信工业财政上的利润将跌至零如果低于当前电台三分之一的国家 /地区的广告转向卫星转播服务。 当然，所以的这些论点都是为了有利于维持全球统一系统，争取建立一个有地方性价值的市场。它的优点是公司设立的支持地方经济建设的传统市场以及政治因素 . 经济上保护他们自己的企业和市场的稳定 . 在政治上 ,支持美国通信委员会委员会的“惯例”，广播公司确认将根据美国通信委员会的现有制度并且和他们过去已经参股。这些条件支持着这样一种观点“美国通信委员会作 为许可证的颁发者和商业上的政治保护者”。事实上，美国通信委员会作为交换服务于当地的区域应该使该广播站（和他们赚钱的权利）得到保证。 nts介绍 1 1 概况 新式数字广播系统 DAB（数字音频广播，现在经常叫做数字广播）是一个具有创新性的和广泛应用的广播系统，他在今后将会在全球范围内代替 AMFM音频广播服务。该系统于 1990 年由 Eureka 的 147/DAB 项目所发展起来。数字广播非常适合移动接收，并且提供了高稳定性，防止了多径接收。 它允许使用单一频率的网络，提高了频率利用率。 数字广播除了具有高性能之外（单信道、双信道、多信道立体声耳机），还可以传输与程序有关的数据和多元的数据服务（比如交通信息、图片和动画等等）。一个网络动态多元管理系统为自由化变成提供了可能性。 在欧洲的一些国家和海外的广播组织中，网络提供商和接收设备制造商将要把运用 DAB 的数字广播服务应用在航天项目和公共服务中。 DAB 与传统的广播系统有很大的差别，有许多组件都是用的新的解决方案并且对于专家来说不象模拟的和数字广播系统那么熟悉的东西，比如说语音编码，新到编码，调制，多元管理或者数据传 输协议。 系统概念 2 1 物理信道 无扰移动接收设备是发展 DAB 系统的基本条件。移动接收设备的特殊问题是有多径传输所造成的：电磁波会散射、折射、反射，会从各种各样的途径到达天线，正如不同传输时间的信号叠加再一起。这会导致由于频率、位置或者（对于移动接收设备来说）时间的干扰。移动接收设备会受到微秒范围内的变化干扰，并且这个变化会随着传输带宽的变化而变化。有人说移动无线电信道是以时间变化和频率选择行为特征的。 时间的变化是由车辆的速度 v 和波长 。 Fo 是传输频率， c 是光速。相对应的物理量是最大多普勒频率： 表 2.1 显示了一些实际相关量 实际相对于车辆速度向量 a 角度的波的多普勒偏移公式由下式给出： nts 音频服务和应用 3 1 概述 DAB 系统视为提供音频服务和附加的数据服务所设计的。这一章关注于主要的音频服务作为中心应用。音频服务用 MPEG 音频层来为收听者提供单音、立体声和多信道的程序。尽管第一个广播应用和接受设备能支持立体声程序，但是转移到多信道服务是要包含到这个系统中的。 数据服务会变得越来越重要并且我们可以看到关于发展的方向和测试的一些新的观点。计算机网络更高级，但是很容易可以看出他的 DAB 系统的数据存储能量只能应用于非常小的服务之中。这一章关注于主要的 DAB 的服务 音频广播服务 还有他的一些标准。我们打算给读者关于音频系统的一个清楚的外表和可能的缺陷，而不用牵扯到影响不到用户的一些细节。 数据服务和应用 4 1 概要 当数字音频广播的发展开始主要集中在音频广播这一块的时候，其数据处理的能力也已经在最开始的时候被设计进入了系统。在 90 年代初成功的推出新型数字音频广播系统之后，这些数据处理能力获得越来越多的青睐并且原始数据服务在 Eureka 147 系统相关的事件中 不同的合作方案被证明（例如： 在拉斯维加斯的全国广播工作者协会， 1992 年春天）。为了协调这些原始数据服务和在设备与服务之间达到兼容性，数据交换的协议和应用程序被定义成与广播的需要相匹配的，服务运营商和用户终端。与此同时它承担了一般的一些数字音频广播频道的容量的使用。特别是对于多媒体数据服务，对于使用者的接受程度和对于该新型数字广播媒介网络的资金筹措来说更是至关重要的。所有这些必要的程序都可以通过这种方法来实现。 4 2 数据服务信号传输 数字音频广播多元化是创办服务和构成服务的。数据的传输可以成为音频广播服务的一个服务成分。例如：如 果她传送的数据是与该（ DAB）服务有关系的，或者如果那是与程序服务无关的，数据服务将被作为单独的服务来传输，并且可能是由一个或几个数据服务成分拼凑而成的。 nts 参考文献： 1Edited by Wolfgang Hoeg/Thomas Lauterbach Digital Audio Broadcasting(principles and applications of digital radio) 2003 2ETI 300 401 ETS 300 401 Radio broadcasting systems Digital Audio Broadcasting DAB to mobile portable and fixed receivers May 1997 nts 福州大学本科生毕业设计（论文） 外文翻译及原文 姓 名： 许恒森 学 号： 1002584 学 院： 物理与信息工程学院 专 业： 通信工程 年 级： 2002 级 2006年 06 月 10日 nts物理与信息工程学院毕业设计（论文）开题报告表 信息与通信工程 系 通信工程 专业 2002 级 时间： 2006.03.20 课题名称 可接收数字广播节目的 GSM 移动终端的硬件设计 指导老师 胡兰馨 学生姓名 许恒森 课题类型 试验研究 进行方式 真题真做 结合情况 科研 承续类型 新题目 课题简介 （基本内容及意义） 基本内容：实现通过 GSM 手机天线接收从移动交换中心（ MSC）发射出的数字广播信号（该数字信号实验中通过数字信号发生器模拟），针对 GSM 模块的功能特点，利用相应的软硬件使该数字广播信号通过解码等过程可在 GSM 手机的扬声器播放出来，并可通过手机键盘控制数字广播接收的开关，音量等功能。 意义：广播作为一种通信手段，是很多人特别是出门在外的人空闲时娱乐或者获得新闻等信息的一种重要手 段。在我国，模拟广播技术已经成熟，在拥有收音机后大部分人可以方便的接收到各自所喜爱的广播节目，但是模拟广播技术有很多缺点，如音质差，抗干扰能力差，移动时接收效果差等。而数字广播作为一种新一代的广播技术，则不存在上述缺点，拥有 CD 一样的音质，不易受干扰，高速运动时接收效果好，除了音频节目，还可以额外提供数字多媒体广播和数据服务。在欧美日等发达国家， DAB（数字信号广播）覆盖率已经达到相当高的水平，而我国目前有北京，上海，广州等地开始在试播，因此，用于接收数字广播的终端必将是未来中国需要重点发展的领域，而我们的 课题主要研究和解决的是如何通过 GSM 手机控制接收端接收并通过手机播放数字广播，以设计出一种可接受数字广播节目的移动终端。 初步方案 我们的方案是在设计上采用以接收机解码模块、数据业务解码器和GSM 通信模块的开发为主线和基础，设计出能通过 GSM 通信模块所在的移动终端控制 DAB 接收机并接受数字广播节目的系统。 具体流程：通过天线接收数字信号，通过高频调谐器、 I/Q 解调器、OFDM 解调器、解复用器后将数据通过 GSM 通信模块的音频解码，在移动终端的扬声器上播放出数字广播。 第一至 二周：完成毕业设计的开题报告，并查阅相关的资料。 第三至四周：深入了解毕业设计的有关任务，并查阅毕业设计课题有关的参考文献，资料的基础上完成“文献综述”的写作。查找与毕业设计题目有关的外文资料，完成外文翻译。 第五至十周：按照任务书的要求进行设计和完成实际操作，并完成对设计成果的检验。 第十一周：完成毕业论文的写作，并完成毕业设计成果演示。 第十二周：做好毕业设计的答辩的准备，完成毕业设计答辩。 nts预计存在的问题及解决方法 1 限于实验室的硬件设施条件，某些东西可能无法实现 ； 2 时间太短，任务可能无法全部完成； 3 由于本课题的研究对象数字广播目前在中国正处于起步阶段，资料相对较少，相应的芯片价格昂贵且可能较难获得； 4 我们本身之前也比较少接触数字广播这方面的知识，可能会遇到很多盲点； 5 接收机可能无法接收到数字信号或移动终端无法控制接收机；由于带宽问题，只能接收到单声道数字广播； 我们将通过各方面的努力，尽量把这些不足弥补上，并且在实验研究的过程中，以获得最多的知识为目标，以端正的态度，努力去做好每一件事。 教研室 意见 院教学指导委员会意见 nts 本科生毕业设计（论文）任务书 2006 年 03 月 20 日至 2006 年 06 月 10 日 题 目： 可接收数字广播节目的 GSM 移动终端的硬件设计 姓 名： 许恒森 学 号： 1002584 学 院： 物理与信息工程学院 专 业： 通信工程 年 级： 2002级 指导教