HiDef Digital: Television Gets Even Better(a)

HiDef Digital: Television Gets Even Better

Are you still using an outdoor antenna to pick up television broadcasts? If so, you may soon find yourself without anything to watch. As of May 7, 2012, the National Communications Commission will require Taiwan's five over-the-air (OTA) television networks to begin switching from analog to digital broadcasts. The changeover will be made in stages, area by area. Once that happens, viewers will need either a TV capable of receiving a digital signal or a set-top converter box to pick up programming.

Digital television will improve the resolution of OTA programming and increase the number of OTA channels from the current five to 16. The move to high-definition programming also offers producers the opportunity to improve the audio and visual quality of domestic programs.

In the old days, people largely relied on outdoor antennas to pick up the analog OTA signals broadcast by TV stations. Their TVs then converted that signal into images and sound. Analog signals are continuous, directional, and extremely susceptible to interference. If the weather was bad or your antenna mispositioned, you'd likely see snow, ghosting, or other visual noise on your TV.

Since many people had no place to mount an outdoor antenna and picture quality with external antennas was unstable, the US began developing shared antenna networks as early as the 1940s. These consisted of a primary antenna, an amplifier, and cable running from the amplifier to customers' homes. Such a setup mounted atop an apartment building could resolve the reception problems of every resident in the building. Later advances in high-output broadband amplifier technology allowed cable television systems to extend coverage to neighborhoods and even entire cities, giving us today's ubiquitous cable TV.

高画质数字元年，电视更好看

你家还在使用传统的户外天线收看无线电视台吗？若是，你很快就会面临没节目可看的窘境，因为自 2012 年 5 月 7 日起，国家通讯传播委员会将要求台湾 5家无线电视台将原来的模拟讯号，改由数字传送。如此转变将分阶段分区进行。一旦出现这种情况，观众要不就是得使用能够接收数字讯号的电视机，要不就是得用机上转换器才能接收得到电视节目。

数字电视将能改善无线电视节目的分辨率，将无线电视频道的数量从现行的 5 台增加至 16 台。这项迈向高分辨率电视节目的举动也提供了让电视制作人能改善国内节目影音质量的机会。

早年，人们主要仰赖户外天线接收电视台传送的无线模拟讯号，再经由家中电视机将讯号转换成影像及声音。模拟讯号是连续且具方向性的，极易受到干扰，只要天候不佳、天线没摆好，电视就可能出现『雪花』、『鬼影』或其他影像上的噪声。

由于许多人没有地方放置户外天线，且使用室外天线接收的影像质量也不稳定，因此早在 1940 年代，美国即起步发展『共享天线网络』。这些网络由主天线、讯号放大器及从讯号放大器延伸至顾客家中的电缆线组成。于公寓顶楼架设这么一座装置能解决大楼内每户的收讯问题。其后由于大功率宽带放大器技术的进展，使得有线电视系统得以延伸覆盖范围至小区或整座城市，给了我们今日普及全球的有线电视。