Everyone knows that the switch to digital television is coming, it’s been advertised for long enough. Unfortunately, though, there aren’t a lot of places that adequately describe just what the switch is about. Granted, most people probably don’t care that much, but I do.
PBS describes things well: http://www.pbs.org/opb/crashcourse/digital_v_analog/
Go there and read for the most detail, but here’s a quick overview. Analog broadcasts transmit a standard NTSC quality picture and two (stereo) sound channels. It uses 6Mhz per channel. Digital broadcsts transmit up to HD quality signals with 5.1 channel audio. Somehow digital signals have to transmit a lot more data in the same amount of space. This is done by compressing the digital video signal using MPEG-2 compression. MPEG-2 has been reported to get up to 100:1 compression, but it’s probably closer to 50:1 on average.
So, with 1/50th of the video data to send (well, not quite since the video is higher resolution), there’s more room for the improved audio quality and potentially a lot of other data.
Keep in mind that TV will still be broadcast over the airwaves, just using the new digital format. Most current antennas will continue to work, so you probably don’t need a new one.
Also, there’s now the potential for one station to “multicast,” which means send multiple signals at once. You may have seen channels like 7-1, 7-2, etc on your new TV. That’s one channel broadcasting multiple signals at once. Generally they are the standard definition and high definition signals, but it’s possible to broadcast different shows at once.
A converter box has nothing to do with your antenna. Yes, you plug your antenna into it, but you only need the box if your TV doesn’t have a digital tuner. If you have cable or satellite, you don’t need a converter box, even if your TV doesn’t have a digital tuner – this is because the cable/satellite box does the converting for you. Those TVs that do not have a digital tuner and are not on cable/satellite require the converter box to convert the digital signal from the antenna into an analog signal your TV can read.
Fun, huh? Digital TV is really going to change things. There’s a whole bunch of extra space to send other signals. Imagine interacting with your TV (kind of like the way you can play games through your cable box), way advanced picture-in-picture features, and more. It will be a while yet, but TV of the future is going to be something else. Watch out for commercials that let you play a trivia game or educational channels that let kids learn to count by selecting numbers in the right order.
We’ll see what’s to come…here’s a nice PDF of the broadcast spectrum: http://www.ntia.doc.gov/osmhome/allochrt.pdf
