共查询到19条相似文献,搜索用时 734 毫秒
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随着数字电视传输技术的不断发展和智能终端的快速普及,数字电视的形式也趋于多样化.在考虑传统IP网络电视、有线电视和广播电视所具有的优势和不足的基础上,克服传统电视系统的缺点,利用IP网络传输的模式,设计并实现了一种基于地面数字广播电视(DTMB)多屏互动系统.通过地面广播电视网与宽带IP网相结合,把地面数字电视信号通过IP网组播方式传送给智能终端设备,能够有效降低对网络资源的消耗,同时保证多台智能设备同时观看电视节目.首先介绍了系统的硬件框图和系统所涉及到的主要芯片,然后详细描述了解调软件设计、IP overTS的实现和客户端软件的设计流程,最后总结了系统可应用的场景. 相似文献
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随着我国具有自主知识产权的地面数字电视传输标准GB 20600-2006《数字电视地面广播传输系统帧结构、信道编码和调制》于2007年8月1日起强制实施,2008年北京、天津、上海、沈阳、青岛、秦皇岛、广州、深圳等8个奥运城市陆续开通地面高清 相似文献
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本研究所设计的经济型宽带DTMB地面数字电视覆盖系统,采用自主先进的国标地面数字电视DTMB国际技术标准,其核心技术为TDS-OFDM和LDPC技术。设计的数字电视地面无线传输系统在抗干扰能力、接收性能、传输速率和容量等实测均表现优异,系统以1个500 W室外防雨型宽带发射机基站为主,天线安装于120 m铁塔的平台上,在40 km内相对平坦的地区能够覆盖90%以上的地方,用户终端可通过7单元室外天线或5单元室内天线接收后,经AVS+数字电视机顶盒收看电视,并在东盟及非洲地区,满足客户需求并推广应用了中国DTMB标准。 相似文献
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输电线路杆塔倾斜度是线路设计与运维均需考虑的重要参数之一,便携高效地实现输电线路杆塔倾斜度的精确测量和数字化描述,具有重要的价值。鉴于现有测量方法的不足和地面三维激光雷达技术的特点,提出了基于地面三维激光雷达实现输电线路杆塔倾斜度测量的新方法,搭建了试验系统,并基于搭建的试验系统开展了现场可行性与对比测试。现场可行性与对比测试结果表明基于地面三维激光雷达不仅能正确地实现杆塔倾斜测量,而且现场测试强度低,测量精度与全站仪测量法精度相当,满足工程测量需求;通过对目标对象的三维虚拟重构,地面三维激光雷达测量方法实现了测量结果可视化化和数字化描述,便于存档和追溯校核;所搭建的测试系统可用于实际工程测量。 相似文献
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《Power Systems, IEEE Transactions on》2005,20(3):1224-1232
The goal of the North Eastern Pacific Time-Series Undersea Networked Experiment (NEPTUNE) is to provide the infrastructure necessary for scientific exploration and investigation on the floor of the Pacific Ocean in an area encompassing the Juan de Fuca Tectonic Plate. In order to achieve this goal, the power delivery capabilities of the terrestrial distribution system will be extended into the Pacific Ocean. The power system associated with the proposed observatory is unlike conventional terrestrial power systems due to the unique under ocean operating conditions. The operating requirements of the system dictate hardware and software applications that are not found in terrestrial power systems. This paper describes a method for topology error identification in the presence of various forms of measurement errors for NEPTUNE, a highly interconnected DC power system. Hardware and reliability requirements have led to a power system configuration that includes a large number of unmeasured sections. Using previously developed state estimation algorithms as a starting point, a methodology for system topology identification is proposed in this paper. 相似文献
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直接序列扩频技术以其优良的抗多径干扰、安全性和测量时间的精确性成为陆地无线测控网中关键技术之一。本文主要介绍在ITURAN测控网定位系统中上行定位链路中的直接序列扩频技术,并采用MATLAB对其性能进行了仿真试验,仿真的结果证明了直接序列扩频技术具有较强的抗多径干扰能力。 相似文献
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针对传统人工测量输电线路方法精度与效率较低的问题,提出一种机载激光雷达系统与地面激光扫描仪协同工作的组合激光雷达系统进行输电线路测量。机载激光雷达系统负责输电线路走廊点云数据的采集,地面激光扫描仪负责电塔高精度点云数据的采集,通过计算两个坐标系之间的旋转矩阵与平移向量,实现两组点云数据的融合。在张北500KV高压输电线路工程中进行应用试验,试验结果表明,该系统可以高效、准确地实现输电线路走廊中危险点的检测以及电力塔的倾斜度与变形监测,具有一定的实用价值。 相似文献
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We have proposed an online navigation system for the visually impaired. In our previous system, we used a pedometer and a terrestrial magnetic sensor. This system has the problems of cumulative errors in the measurement of walking distance and errors in the detection of walking direction due to the lean of the terrestrial magnetic sensor. In this paper, we develop another navigation system that uses a guide stick to which is attached a small wheel at the end of the stick instead of a pedometer and a device for keeping the terrestrial magnetic sensor horizontal in order to improve the problems of the previous system. Thus, we can obtain a more exact walking locus. To navigate the visually impaired, we propose a method using auditory signals consisting of voice sound and buzzer. Further, we attach an answering machine to the guide stick to provide the required information whenever requested. To evaluate the navigation system, we conduct walking experiments using blindfolded and visually impaired individuals. It is seen that this system can guide them to a destination at a distance of about 620 m and is useful as a navigation system for the visually impaired. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 119(3): 69–80, 1997 相似文献
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Understanding and measuring circular polarization 总被引:1,自引:0,他引:1
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数字(高清晰度)电视机顶盒音频系统研制 总被引:2,自引:0,他引:2
适用于地面、电缆传输系统的数字高清晰度电视接收机顶盒,正在由研制阶段走向规模化生产。本文介绍了所研制的机顶盒中音频系统结构、关键芯片及配套软件。实验证明本系统性能良好。 相似文献
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《International Journal of Electrical Power & Energy Systems》2013,44(1):54-62
Voltage source converter, multi-terminal HVDC transmission (MTDC) for the connection of large offshore wind farms to the terrestrial grid is investigated. Induction generators without the need of wind turbine converters are installed in the wind farms due to the supports from the voltage source converters of the HVDC. A control system is designed which incorporates the voltage–current characteristics of the voltage source converters and the power reduction from the wind turbines during a fault. During normal operation, grid side converters control the DC voltage and coordinate the power sharing to the terrestrial grids. During abnormal operation, wind farm side converters take over the DC voltage control and coordinate the power reduction between wind farms. The control system removes the requirement for fast communication between the converters and achieves automatic coordination. The dynamic performance of a MTDC with the control system is tested through simulations using PSCAD/EMTDC. 相似文献