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技术资讯 => 数字视频同轴电缆的选择	【打印此页】【返回】

发布日期：[2007-6-10] 共阅[4747]次

数字视频电缆的选择

精密视频电缆被推荐用于最新的数字视频应用领域中。自80年代初期以来，数字广播很快变成了为大家所喜爱的视频模式。数字模式的优点有很多：数字方式很稳定，大大减少了设备调节；复制或再制作能够保持原有的品质；信号衰减几乎被消除；抗噪能力大大增强。数字视频在电缆中的传输采用的是并行方式或者是串行方式。并行数字视频(D1，D2&D3) 并行模式是将8位或10位数码的每一位同时传输，或者以27Mb/S的数率沿着单独的信号通道并行传输。这种传输要求使用100欧姆至120欧姆的12-1/2对的数据电缆。这些电缆的传输距离低于30米。串行数字视频(D1，D2&D3) 广播市场出现的最新技术是串行数字视频。串行模式是将数码的每一位通过一根同轴电缆依次地，或者说顺序地传送。同轴传输允许的传输距离要长得多(300米以上)。数据传送速度根据模式不同可达到143至360Mb/S。因为涉及高频，阻抗公差、稳定的高频响应及屏蔽就成为关键因素，使得精密视频电缆在这些应用场合必不可少。串行数字电缆在不久的将来，视频技术如分立宽屏幕或者高清晰度电视(HDTV)将会要求360Mb/S以上的传输速率。为了在要求高频技术应用的场合发挥最大的性能，特提供“低损耗串行数字同轴电缆”以满足更高的要求。在现有的串行数字频率基础上，这种RG－6结构(型号：1694A)比起传统的精密视频电缆衰减降低了20％；在1GHZ时衰减降低30％。这种性能的改进使得在更长的距离情况下也能进行无误传输。通常精密视频电缆用于关键性的模拟及数字视频电路，以及高品质的应用场合，如在演播室中的现场直播和前期及后期的制作设备；这种在对传输信号完整性有较高要求的场合应用这种电缆。精密视频电缆通常有实心中心导线及双重屏蔽。其绝缘介电层既可以是泡沫状的，也可以是实心的。严格的阻抗和衰减公差、卓越的结构回波损耗(SRL)指标以及改良的屏蔽使精密视频电缆拥有优良的性能。实心介电层电缆的频率响应损耗曲线(如8281)，与那些泡沫状介电层电缆(如1505A)不同，需要不同的均衡器。因此，基于这个原因不要将8281与1505A混用。 ※如果实际应用中有其他特殊要求，例如：长度、颜色、包装、防火等级、环保认证等。


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There is a making wow gold guide for lower levels. If you are interested in it or just at lower levels, pay more attention to this guide.There are countless of ways to earn money in World of Warcraft, but it is not even worth to list all the ways because it would take too much space. You probably just want to know about the very best ways of world of warcraft gold making and not some mediocre way.Professions are the most profitable way to earn wow gold money. That is if you pick the right profession for your way of playing World of Warcraft. But at the very beginning, the best professions to start with are Sinning combined with Mining or HerbalismBecause of the fact that Mining and Herbalism need a reagent-tracker to be active for you to see the spot to farm these on the minimap but Skinning doesn't need this.There are the core wow gold makers for the player between levels 1-59. 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