共查询到18条相似文献,搜索用时 218 毫秒
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电视接收机本振泄漏对CATV系统的干扰山东招远市广播台王国梁,刘丛云电视接收机本振泄漏对CATV系统造成的干扰,在多频道系统中经常发生。这种干扰很容易与交调、互调干扰现象混淆,不被工作人员注意。而分配系统中电视机的本振泄漏在一定条件下对CATV系统产... 相似文献
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乡镇广播电视站的有线电视机房基本上是和有线广播机房合在一起的,由于在设计和施工中没有考虑到有线电视系统接地的重要性,有的乡镇广播电视站有线广播的工作接地和保护接地没有分开,将有线电视系统前端的接地同有线广播的工作接地合在一起,严重影响了有线电视系统的技术指标。接地对有线电视系统影响的原因有两种:一是机房地与外线(主干线)地之间由于位差所产生的交流回路。故障现象:①用户电视接收机的伴音产生交流哼声。②干扰电视接收机图像:白条干扰、黑条干扰、50Hz、100Hz(倍频)干扰,并上下滚动,黑白条宽度基本上不变,严重时造… 相似文献
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有线电视系统输出电平的调整非常重要,既要与电视机的入口电平相匹配,又要符合广播电视标准,即输出电平最小值为60dB,最大值为75dB,而网络常见故障有交互调干扰、重影干扰、交流滚道干扰、本振干扰和雪花干扰等,掌握这些干扰故障的检修技术是有线电视维护人员必备的知识。 相似文献
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针对有线电视系统中交流声干扰对终端接收图像的危害,探讨了形成交流声干扰的各种因素,并针对有线电视系统中有源设备接地不当、电磁环境造成的交流声干扰,尽可能全面、系统地找出交流声干扰的对抗手段和措施,达到抑制交流声干扰的目的。 相似文献
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有线电视系统采用大量的增补频道,结合实际应用分析增补频道的使用情况,介绍增补频道在有线电视系统传输频带中的划分和范围,以及新老型号电视接收机增补频道的设置情况,详细阐述利用老型号电视接收机接收增补频道节目的方法。 相似文献
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The carriage, on cable television, of signals in the presence of a strong, ambient, co-channel field intensity generally results in interference between the desired signal delivered by the cable and a signal picked up by leakage either in the receiving set or the cable itself. An analysis of this phenomenon suggests various techniques for detecting and measuring the interference. 相似文献
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通过Excel设置的分光比计算模板对有线电视网络中光分路数的内在规律进行探析,从而明了有线电视网络中最佳光分路数随着光发射机输出功率与光接收机的输入电平的改变而改变,揭开了有线电视网络所传输的光链路总(或平均单路传输)距离所对应的最佳光分路数设计的规律与思路,恰当应用这一规律与思路,能有效地提高网络的性价比。 相似文献
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吴江有线数字电视平台于2007年6月建成,并投入试运行,同年8月吴江数字电视整体转换开始,系统正式投入商业运行。结合吴江数字电视的技术维护情况,对引起有线数字电视故障的各种噪声干扰的形成原因进行试探性分析,并提出一些值得借鉴的解决和预防措施。 相似文献
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A review is presented of the current television broadcasting situation in European countries, which involves a varied mix of terrestrial VHF or UHF systems and cable networks. A small market has emerged in Europe for receivers using the low-power telecommunications satellite transmission between the program providers and cable network companies. This is expected to change with the launch of medium-power pan-European telecommunication satellites (e.g. ASTRA, EUTELSAT II), which are now directly addressing the market of home reception. DBS (direct broadcast satellite) in the UK, using the D-MAC transmission standard, will offer three additional television channels, data broadcasting services, and a planned evolution to compatible forms of wide-screen, high-definition television. Comments are given on receiver and conditional access system standardization. Some views are expressed on satellite broadcasting as part of an overall broadcasting framework for the future 相似文献
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有线电视数字化是当今世界广播电视发展的重大技术革命,是经济社会信息化的重要标志,更是国家加快宽带通信网、数字电视网和下一代互联网等信息基础设施建设,推进三网融合的需要。当前全国各地农村正在有序推进有线数字电视双向网改造和整体平移,大量资本的投入,如何产出最大的经济效益,这是对我们这代广电人的一大考验。结合当前安吉县报福镇部分农村有线数字电视双向网改造和整体平移的实际情况,阐述农村营销新模式,推动农村有线数字电视经济效益最大化。 相似文献
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Junshan Zhang Chong E.K.P. Tse D.N.C. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2001,47(3):1128-1144
Multiple-access interference (MAI) in a code-division multiple-access (CDMA) system plays an important role in performance analysis and characterization of fundamental system limits. We study the behavior of the output MAI of the minimum mean-square error (MMSE) receiver employed in the uplink of a direct-sequence (DS)-CDMA system. We focus on imperfect power-controlled systems with random spreading, and establish that in a synchronous system (1) the output MAI of the MMSE receiver is asymptotically Gaussian, and (2) for almost every realization of the signatures and received powers, the conditional distribution of the output MAI converges weakly to the same Gaussian distribution as in the unconditional case. We also extend our study to asynchronous systems and establish the Gaussian nature of the output interference. These results indicate that in a large system the output interference is approximately Gaussian, and the performance of the MMSE receiver is robust to the randomness of the signatures and received powers. The Gaussianity justifies the use of single-user Gaussian codes for CDMA systems with linear MMSE receivers, and implies that from the viewpoints of detection and channel capacity, signal-to-interference ratio (SIR) is the key parameter that governs the performance of the MMSE receiver in a CDMA system 相似文献