HDTV, SDTV & DTV!
Apr 27 '01
The Bottom Line HDTV is the future in TV viewing. Not only in picture quality but also in better audio and the size of the screen.
If things aren't confusing enough, here are three TV standards that all come together to give you the future of HDTV.
This is a listing of the digital formats now in progress with a little description on each one.
SDTV
SDTV stands for Standard Definition Television, which is similar to the standard TV modes of today with the exception that it is broadcast in digital and not analog.
It transmits 480 vertical lines and 640 horizontal lines progressively. It can also be transmitted in an interlaced transmission mode.
With this transmission you have good picture and sound quality. You won't hear any hissing sound in the audio, it is crystal clear. You won't see any ghost features in your picture quality like in our standard TV formats of today.
If your TV is not digital ready, you will need a decoder box to convert the digital progressive or interlace scans and MPEG pictures into your standard analog signals for display on non-digital TVs.
DTV
DTV stands for Digital Television, it sends pictures and sound as an on/off digital stream rather than analog signals of today.
You will need a digital TV to use DTV or you may buy a decoder to make your older TV viewable with DTV. A decoder will not improve your picture resolution quality, you will need to buy a digital TV for that.
DTV is versatile, it uses MPEG-2 compression that allows, one high-resolution, a wide-screen program or, 4 standard-resolution video programs to be multiplexed on a single channel rather than several channels.
As of now and this can change anytime, all US TV stations must switch to all digital on channels 2 through 51 by 2006. In the meantime they will broadcast on two channels for 2 through 51, one in analog and one in digital. After 2006 the analog channels are to be shut down, so if you haven't bought a digital TV by then, you will have to buy a decoder box.
DTV will be able to broadcast in the SDTV, HDTV and a medium digital resolution mode.
The medium mode will be in 720 vertical lines progressively, this is similar to a Computer monitor.
So DTV will be able to be broadcast in 480, 720 or 1080.
HDTV
HDTV stands for High Definition Television, which is, suppose to change the standards in picture quality and viewing. HDTV is in a digital format.
One aspect of the change for better picture quality, remember the current vertical lines on today's standard TV are at 480 vertical lines. The HDTV vertical lines as of right now are set at 1080, so you see there is over twice as many vertical lines. It can be transmitted in progressive or interlaced scanning.
HDTV will be in a Widescreen picture of 16:9 compared to today's TV of 4:3. What this breaks down to is for every 16 inches you have in width you will have 9 inches in height. The old format is for every 4 inches in width you have 3 inches in height.
The reason for the 16:9 format is that it is real close to what they use when they make a movie. The idea behind it is so you won't miss anything on a movie because it wouldn't fit on the screen.
Interlaced & Progressive
Interlaced scanning is a video component or signal that assigns alternating scan lines in a video frame to one of two fields, which are then displayed separately.
Progressive Scanning is a video component or signal that processes or displays each scan line of a video frame in sequence.
Digital Sound
Dolby digital 5.1 (Dolby AC-3) is slated to be the sound format for HDTV, though this and anything else about HDTV could change. What ever they use, it seems the two-speaker system for the future is out and a five speaker plus a subwoofer system is what they are going for.
My Last Words
This is a light description of HDTV. I tried to write this review in a way that a lot of people would understand, instead if all the technical data that I could have added.
HDTV has been in development for many, many years and has taken a lot of changes because everyone is fighting to get in on the action. I do believe it is time for the FCC to make a final decision on what HDTV will be so the consumer can buy what is needed. How it is now, you may buy a digital TV and still need some kind of a decoder in the future to get the true picture.
HDTV is a very complicated issue and I look for it to be that way for years. I bought a Hitachi 60" big screen four years ago and I remember a lot of people saying "why" they are going to digital in a year and Widescreen a year after that. All I can say is, I am glad I bought that TV four years ago because it has given us a lot of enjoyment. As of today the only way I can get digital viewing is from my DVD player and my Direct TV.
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