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Published:March 12th, 2007 07:40 EST
Digital TV: The Picture of Tomorrow, Today

Digital TV: The Picture of Tomorrow, Today

By George Gildersleeve

Soon all TV signals will be digital, are you ready?

March 1, 2007 was the deadline set by the FCC telling TV manufacturers that every television they make has to be digital. I am sure you have heard about digital and analog TV signals but what exactly does this mean? For a few years, it seemed that when anyone heard the word digital in regards to television they automatically thought about the price. Many people have a misconception that all digital TVs are high definition, this is a common, easily made mistake. HDTV’s are digital, but not all digital TVs are high definition. In this article, I will explain the differences between analog and digital signals, and the differences in television sets.

In January of 2009, all television broadcasts in the United States will be in digital format as opposed to the analog signals. Analog signals have been used since the television was invented and John Baird sent a moving picture from one room to another. Needless to say, we have come a very long way since then and are continuing to develop newer and better ways to transmit these signals. We have moved through the ages of color TV, stereo sound, and closed captioning, all of which are very important landmarks in the TVs history. To help you understand what this change to digital broadcasts means, let me first explain the difference between the two types of signals.

Analog signals are transmitted much like radio waves. Power lines, range, and various other factors affect the signal. The interferences affecting the analog signal causes on-screen picture problems such as ‘ghosting’ and ‘snow’. Analog TV picture is broadcast on AM frequencies while the audio signals are broadcast on FM frequencies. Also, because of the frequency range of analog signals, the picture resolution (the amount of dots/lines that make up the picture) is very limited and not capable of handling much high definition content, they don’t have the ability to have ‘in-between’ channels for extra content or alternate languages on your favorite channels, and can only carry a limited amount of closed captions.

However, digital Signals are much different. The signal for a digital TV is broadcast very similarly to the way a computer writes data, think binary. The signal is a series of 1’s and 0’s. The signal sends information as either ‘on’ or ‘off’, ‘1’ or ‘0’. With a system like this, a viewer sees the picture either perfectly or not at all. If a digital TV is receiving a digital signal, it will get all of the information possible from that broadcast. Because of this method, power lines, distance, etc. do not adversely affect digital signals. Digital TV also has much more flexibility over the content being carried. It can be interlaced (lines of the TV refreshing ½ at a time) or progressive (lines of the TV refreshing all at once), it can transfer black & white, color and multi-channel audio on one signal.

In addition, since digital TV is made of ‘bits’, a digital signal of the same size as an analog signal can carry much more information because it uses the space that would be in between the frequencies in an analog signal, and can carry extra-channels, multiple languages, higher quality audio, more captions, etc. So in short, a digital signal can carry much more information in a signal that takes up the same amount of space as a regular analog signal. Digital TV can also transmit a high-definition picture without getting any of the adverse effects of its analog counterpart.

Lastly, a major difference between analog and digital signals is the fact that digital TV can broadcast a true 16:9 widescreen picture. This means that instead of your standard 4:3 (4 measurement units on top to every 3 down the side) picture you receive via analog transmission, you can get a 16:9 (16 top measurements to 9 on the side) widescreen picture, which is what you, see when you go to a movie theater. This means that you can view the picture that the filmmaker intended you to see. Usually, since movies are recorded in widescreen format, the picture you see is either cut on the sides or squeezed to fit you standard TV. This also eliminates those annoying black bars on the top and bottom of the screen if you watch a movie on a standard TV.

With the explanation of the signals done, I will proceed to explain some of the HDTV jargon you may have heard and try to make some sense of it. Since all TVs being manufactured now are digital, they will almost definitely all be widescreen (16:9). Now to explain the different types of definition on TVs. Standard definition TVs display 480 horizontal lines, which refresh themselves 240 lines at a time. Enhanced definition TVs (EDTV), have 480 horizontal lines that all refresh at the same time. These types of resolution are called 480i and 480p respectively, i being interlaced (for refreshing half) and p being progressive (for refreshing all at once).

High definition TVs are called high definition because they have more horizontal lines making up the picture. There are currently three types of HDTV, 720p (720 horizontal lines refreshing at the same time), 1080i (1,080 horizontal lines refreshing ½ at a time), and 1080p (1,080 horizontal lines refreshing at the same time). 1080p is currently the newest and clearest form of HDTV, but most are rather pricey. 720p has been the preferred mode of many people for quite a while. Although 1080i has a higher resolution, people did not like seeing flashing occasionally in their peripheral vision.

In closing, the FCC mandate for TVs manufactured to be digital is already in place, and soon the mandate for all TV signals to be digital will be upon us. You do not need to rush out and buy a new TV just yet, but keep this information in mind, as it will be valuable in the near future when you are required to get a new TV. I hope this will help you understand TVs a little bit more and to understand exactly what it is that the FCC is mandating.