As today is the day that all of the US switches their over the air signals to digital. I thought it would be a good time to update a popular post HDTV Explained
Click on the link for the post.
When you look at your old CRT television it is slightly wider than it is taller. This ratio is described as 4:3. Meaning it is 4 units wide by 3 high. The newer flat panels (and even some CRTs) came out in the wide screen format. This aspect ratio is described as 16:9. This is the standard for most flat panel screen, whether they be LCD or Plasma. The 16:9 ratio is closer to the theater experience, that allows you to see all of the picture.
Most of us have computers. And most of us are familiar with screen resolutions of 800 x 600 or 1024 x 768. This was the number of pixels tall and wide. With TV’s there is a new form of measurement, 480i, 480p, 720p, 1080i, 1080p. Let’s start with your old CRT. Most CRT TVs are either 480i or 480p. The i stands for interlaced and the p stands for progressive. CRT TVs use an electron gun to scan lines onto the screen. Interlaced means every other line. So if a TV says it supports 480i, then at any instant in time there are actually 240 lines on the screen, followed by 240 lines a split second later. It happens so fast that, you can’t really see it, but some notice the flicker. Next is 480p. This was a standard that we started seeing in DVD players a few years ago, when they say they are progressive scanning DVD players. This means there are 480 lines on the screen at one time. You may notice that some TVs, both CRT and flat panel are called EDTV. This stands for Enhanced Definition TV. These TVs will show a maximum of 480p, and are not to be considered HDTV. Make sure you don’t get fooled by the lower pricing on EDTVs. These will not give you the HD experience.
HDTV starts at 720p and up. This means there are at least 720 lines on the screen at one time. HDTV also includes 1080i and 1080p. This is where most people get confused. Recently many of the new TVs have come out with 1080p and have started calling themselves Full HD or True HD. This is just marketing. The main thing to keep in mind, is that HD content from broadcasters (either cable or satellite) is available in 720p or 1080i. To get 1080p content, you need to have a Xbox 360, Playstation 3, HD-DVD player or Blu-ray player. When you talk about screen resolutions, similar to the computer screen resolutions, here is how it works.
The second number will tell you the maximum HD resolution you can have. (keeping in mind the difference between i and p). For example, if you look at the most common resolution of 40"-42" flat panels, you will see them stated at 1366 x 768. So looking at the second number, this screen would allow for 720p or 1080i. (remember, i scans every other line). But this screen could not do 1080p as the resolutions for this format is 1920 x 1080. If you buy a panel today that can only do 1080i, it doesn’t mean you are behind the times. Think of it as a starter system. The pricing on 1080i systems has dropped tremendously over the past 3-4 months. 1080p systems, are new and therefore the pricing is higher and will be some time before they drop down.
Consumer vs. Commercial Flat Panels:
Lately consumers have started to see, what many manufacturers refer to as their commercial or professional series, flat panels. These units are the same display, but with our the TV tuner or speakers attached. At first many think that these units are a bad idea But when you really think about it, if you connect to satellite or cable, you don’t need tuner as the set top box supplies one for you.** Plus, if you have a surround sound system, there is no reason to use the speakers attached to the system. There is no difference between the picture quality between the consumer and commercial systems as they use exactly the same glass. Many times by not having the tuner or speakers you are getting the same quality at a better price.
Most flat panels today have a number of connections at the back. Which one to use will depend on what you are hooking up to the set. You should know, that in order to get HD resolution you have 3 choices. Component (red, green, blue cable), DVI or HDMI. Component is an analog cable that is the same on many DVD players. This will allow you to get up to 1080i on your flat panel. DVI and HDMI are digital cables. They will allow you to get up to 1080p. The video signal on both cables is the same. With HDMI, they add the audio signal on the same cable. I am always confused as to why someone would want to run an HDMI cable to their flat panel. First, they are expensive. Some are as high at $200 for a 4 ft. cable. Second, most people who have a flat panel TV, will have spent some money on a surround sound system. Granted the speakers that come with today’s flat panels are much better than the old CRT speakers. They don’t come close to the quality of your surround system. So my recommendation is to go with component or DVI and put the sound through your surround system. Use the menu on your TV to turn off the speakers that are attached to your TV. I can’t stress enough, the cables you should not be using are the composite, which is the single yellow RCA type plug. Or the small 5 pin S-video cable. Neither of these 2 will give you the HD resolution that you paid for.
Plasma vs. LCD:
A year ago plasma was the leader for large flat panel TVs. For a few reasons, better contrast (blacker blacks), cheaper and a wider viewing angle. LCD is making tremendous strides, and for a panel under 40 inches, I would probably go with LCD. But for greater than 40 inches it is still plasma that has the biggest bang for the buck. This is changing and could be the other way around by the end of this year. The old myth of plasma burn in has been fixed by most mainstream manufacturers by a number of methods. It really comes down to a personal choice. If you have a home theater environment, then plasma is probably the way to go. If you have a bright room, and you will be watching the TV straight on, then LCD would be a better choice. At the end of the day, put the 2 screens side by side and see which one has the better picture.
If I have missed anything or you still have questions, leave a comment at I will add to this explanation.
June 2009 Update:
Today, June 12th the US is converting their Over the Air signals to digital. Now, for most people this is a non-issue, as many are using some form of set-top box that is connected to a cable company or a satellite company. For these people there is no change. But there are many in rural areas who will be affected, as they receive their signals exclusively via antenna. At the same time this offers opportunity for some located near urban centers to receive free HDTV signals.
The reasons for the changes to digital are complicated. Basically they are running out of room on the frequencies that broadcast signals, so they need to shuffle some things around. It also helped to push broadcasters into the digital era of HDTV.
**The new opportunity lies for those within 30-50 miles of an urban center with a wide selection of TV stations. You now have the opportunity to get rid of you cable or satellite provider, or at the very least, reduce the amount of money you are paying. If you are close enough you can install an antenna to pick up the signals for your HDTV. Keep in mind that you will need a TV with a digital tuner (look for ATSC) to do this. Yes I know, this contradicts what I said above with regards to commercial HDTVs. A friend of mine discusses this in this post.It is easy to do and best of all it is free. It will be interesting to see how this impacts HDTV signal providers over the coming months. I would suspect that most would not know about it and will go with cable or satellite.