July 8, 2008
Moving from Analog to Digital TV
Moving from Analog to Digital TVBy Scott Nesbitt – Sunday, July 6, 2008 |
By this time in 2009, television as you know it will have changed. It's not that the quality of what you're watching will be any better or any worse (although you'd hope that TV shows will get better!). It's how you're getting those programs over the air that's going to change. This TechTip looks at the coming changes to the way in which you get your over-the-air TV and what you can do to adapt. What's going to happen?The United States Senate has told broadcasters that they'll have to end their analog transmissions by midnight on February 17, 2009. Broadcasters, at least those with full-power television stations, will have to broadcast all programming in digital. According to the Federal Communications Commission (FCC):
Notice I said full-power television stations earlier. Analog TV will still be available, mainly through local stations and ones in certain urban and rural areas which relay transmissions from larger broadcasters to smaller markets. In case you're wondering what's going to happen to the analog frequencies that digital is replacing, they'll be used for emergency services and to provide expanded wireless and wireless broadband services. Regardless, the move to all-digital is seen by many as a good thing. It will really improve your viewing experience. What's the difference between analog and digital?The biggest difference is quality. Digital looks and sounds better than analog. Here's a short comparison of how both of them work. Analog TV, which is what those without satellite or cable grew up with, works by grabbing transmissions out of the air in the same way a radio grabs radio waves. This explains the need for an antenna outside your home or the so-called rabbit ear antennas on top of a set. An analog transmission starts as a set of moving images taken by a video camera at about 30 frames per second. The camera converts the images into a set of pixels, and gives each of those pixels a color and a level of intensity ranging from dim to bright. The pixels are combined into horizontal and vertical rows that an analog TV can interpret, and a sound signal is added. The video and sound are then converted to radio waves of specific frequencies (depending on the channels you're watching) and sent over the air where your TV can pick them up using an antenna. Analog TV works, but it's not great (as you probably know) and it's far from efficient. The resolution is nothing to write home about, and the signal itself can suffer from interference — the all-too-familiar snow and static. Digital TV (sometimes called DTV), on the other hand, is far more efficient and the quality is higher. Whereas analog TV is made up of pixels, digital TV is made up of packets of compressed data — if you've watched YouTube or Hulu (or any other online video), then you've seen digital video in action. But unlike many online videos, digital TV isn't fuzzy or distorted. The compression is unobtrusive but has an interesting side effect. Broadcasters can pack more information and more image and sound resolution into a digital transmission than into an analog one. So much so, that a digital broadcast can contain what are called subchannels. Each subchannel can carry a different program without using additional bandwidth. That's the multicasting that the FCC mentioned earlier. On top of that, digital transmissions aren't affected by interference — say goodbye to snow!
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