Originally posted by: shurik92
What is the difference between HDTV and EDTV?
(i know its a stupid question, but I just started shopping for one and did't get a chence to do alot of reaserch yet)
Depends on if you're talking practice or theory.
In theory, ED should be able to fully resolve 480p. 480p is 720 x 480, but it's in a 16:9 format. When you display this on a square pixel, fixed pixel device, you need 854 x 480 to fully resolve it (or 852 x 480 with 1 pixel wide column on either side ignored).
In theory, for HD, you should be able to fully resolve 720p or 1080i. Since 720p is the easier one to hit, that's the one to focus on. 720p requires 1280 x 720 pixels, 1080i requires 1920 x 1080 (though interlaced).
In practice, practically everyone fudges the numbers.
When we're talking 42" plasmas, there are no truly HD units. HD 42" plasmas are either 1024 x 768 (using rectangle 4:3 pixels), or 1024 x 1024 (using alternating light surfaces... a fancy name for a kind of interlacing).
Now, basic gradeschool math tells us that if you need 1280 pixels in width for 720p, 1024 should not be enough. Makes sense, right?
Well, manufacturers hope that customers are ignorant of this requirement.
When we talk about CRT's, things get even more fuzzy. CRT's are, for the most part, 1080i "native". However, they cannot fully resolve this. Even the best 9" CRT's can only hit 1600-1650 or so pixels in width, when perfectly calibrated. The vast majority of CRT RPTV's use 7" CRT's, which only do about 1200 pixels when perfectly calibrated (Pioneer Elite's use very good 7" CRT's which can do perhaps 1400 or so). When uncalibrated, they can only resolve much lower resolutions.
Also consider, most CRT TV's have a low bandwidth video amplifier, from 10mhz to 40mhz or so.
They also have rather coarse lenticular screens.