Digital audio broadcasting requires a purpose - built receiver incompatible with the existing analogue model . we are planning to set up trial points at different locations in hong kong island , kowloon peninsula and shatin in early 2005 to let public experience the high sound quality of this new technology 在dabbandiii测试期间，我们计划，在2005年初，于港九市区及沙田不同地点，设立试听站，让普罗市民感受，利用这项崭新的广播科技可以达到的高音质的效果。
Digital audio broadcasting requires a purpose - built receiver incompatible with the existing analogue model . we are planning to set up trial points at different locations in hong kong island , kowloon peninsula and shatin in early 2005 to let public experience the high sound quality of this new technology 在dab band iii测试期间，我们计划，在2005年初，于港九市区及沙田不同地点，设立试听站，让普罗市民感受，利用这项崭新的广播科技可以达到的高音质的效果。
Due to a variety of its advantages such as high bandwidth efficiency and robustness against multi - path delay , it has been widely used in the fields of digital audio broadcasting , digital television and wireless local area networks and is likely to become one of key technologies of fourth generation mobile communications 由于具有很高的频谱利用率，很强的抗多径延迟能力，它已经广泛的应用在数字音频广播、数字电视以及无线局域网当中，并有望成为第四代移动通信的关键技术之一。
Product categories include : aerospace consulting ; broadband technology ; broadcast / satellite services ; billing / subscriber management systems ; cable / connectors ; data / digital audio broadcasting ; electronic power ; engineering services ; ip networking ; microwave products ; mobile media ; networking hardware / software ; satellite operator / carrier ; system integration ; telecoms ; test equipment ; transmission services and webcasting 产品类别包括：航空咨询；宽带技术；广播/卫星服务；付款/定购管理系统；电缆/连接器；数据/数字声讯广播；电力；工程服务； ip网络；微波产品；移动媒体；网络硬件/软件；卫星控制器/载波；系统集成；电信；测试设备；传播服务和网络广播。
Orthogonal frequency division multiplexing ( ofdm ) has been widely used in many systems such as digital audio broadcasting system ( dab ) , digital video broadcasting system ( dvb ) , high definition tv ( hdtv ) and wireless local network . ofdm will be critical technique in broadband wireless mobile communication system in future 正交频分复用( ofdm )技术已经被广泛应用于数字音频广播、数字视频广播、高清晰度电视、无线局域网等系统中，在未来的宽带无线移动通信系统中， ofdm也将是一项必不可少的技术。
Firstly , in this dissertation , two types of symbol start time estimation schemes for orthogonal frequency division multiplexing ( ofdm ) systems are evaluated and analyzed . simulation results suggest that : pilot symbol based synchronization has better performance over cyclic prefix based schemes , and it performances improved when the length of pilot symbol increases ; cyclic prefix based synchronization method has a high spectrum efficiency in spite of its relative low acquisition of synchronization rate ; and the former is more suitable to bursting symbol based information systems , such as ieee802 . 11a , while the later can be used in broadcasting systems for continuous media streams , such as digital video broadcasting systems , digital audio broadcasting systems 首先,论文从同步获取的角度对ofdm系统中的两类时域符号同步方案进行了性能分析,并通过大量的仿真说明:基于训练序列的同步方法具有较好的同步获取成功率,其性能随训练序列的长度增加而改善;基于循环前缀的同步方法,其同步获取成功率较低,但是具有较高的频谱利用率;前者适用于突发数据帧传输系统,如ieee802 . 11a等,后者适合广播式连续媒体流传输系统,如数字音频、数字视频系统。
