The Difference Between DTV, HDTV, and the technology they replace; SDTV

Jason Fritz

Administrator
Staff member
#1
What is DTV? Is there a difference between DTV and HDTV?

Before you upgrade your existing TV with a digital-to-analog converter box or purchase a new television set, you’ll want to be able to distinguish the difference between the two video signals.

This guide will hopefully give you a very basic run down about Digital Television (DTV), High Definition Television (HDTV), and the technology they are replacing…Standard Definition Television (SDTV).

If you're looking for more in-depth information about DTV and HDTV, I highly recommend the following resources:

High-definition television - Wikipedia, the free encyclopedia
The Difference between HDTV, EDTV, and SDTV
HDTV FAQs: What is the Difference Between Digital TV and HDTV?



Before DTV there was SDTV…

The digital transition on February 17th, 2009 will bring an end to analog broadcasted signals for over-the-air stations in the U.S.

Analog televisions signals are classified as Standard Definition Television (SDTV) signals, which are broadcasted to your television set at the rate of 480i lines of information per each frame. Since the average television will display 30 frames per second, you can immagine just how fast 480i lines have to be displayed across the entire screen.

Why is there an "i" after the 480? The "i" refers to interlacing, and it was created to reduce the amount of information (also known as bandwidth) sent by television broadcast towers to consumer television sets. How does it work? Each frame of video is actually displayed in two different phases. The first phase paints the odd number lines out of the 480 lines on a television set, and the second phase paints the even lines.

So, what's wrong with SDTV and 480i, why the upgrade to DTV?

On smaller television sets (21" and smaller), 480i has great picture quality because the lines of resolution and interlacing are small, and hardly noticable to a viewer.

On larger television sets, the lines of resolution grow in size, causing the interlaced lines to become more noticable. The overall picture quality suffers as well, due to any small imperfections being blown up on a larger screen that wouldn't normally be seen on a smaller screen.



As sales in large screen television sets have grown in the past two decades, so has demand for better picture quality. So what can be done to increase picture quality?
  • Increase the lines of resolution from 480 to 720 or 1080
  • Go from interlaced to progressive scan, which means your TV will display a complete scan for each of the 30 frames instead of the two phases that are used to complete one frame for interlaced.

DTV (also known as EDTV) and HDTV

DTV: The Digital Transition Will Make DTV the Standard in Television Viewing

DTV (also known as EDTV: Enhanced Digital Television) is the next step towards improving television technology, by broadcasting TV signals at a resolution of 480p per frame. The "p" is defined as progressive scan, and it paints a complete frame on a television, instead of painting the frame in two phases like Standard Definition Television broadcasts.

DTV will also provide surround sound audio, but will require extra equipment and cables, which is a little bit outside the aim of this article. Please post questions if you have any...

16:9 Aspect Ratio and the Black Bars at the Top and Bottom of a Television

With DTV at 480p, you're able to receive a much more fine or sharper picture, and you get another benefit: 16:9 aspect ratio (also known as wide screen). Broadcasts set at a 16:9 ratio will provide a viewer with a theater like experience by providing more picture information on the left and right sides of a television screen. A common complaint about this technology is that a viewer is forced to see black bars on the top and bottom of a television screen. To remedy this, most new television sets are now sold with a 16:9 aspect ratio screen, which can reduced but not always eliminate the black bars at the top and bottom of a screen.

If DTV provides a better picture, how does it differ from HDTV?

In short, HDTV is DTV, but DTV is not HDTV. Confused? :p

HDTV broadcasts provides more lines of resolution than the standard DTV broadcast. Since DTV has 480p lines of resolution, HDTV can be broadcasted at three different high-definition broadcasting formats: 720p, 1080i, and 1080P.

720p is a progressive scan with 720 lines of resolution.

1080i is interlaced with 1080 lines of resolution.

1080p is progressive scan with 1080 lines of resolution.

In terms of which is the better picture quality, generally you can assume that the higher the the lines of resolution, the better the picture quality.

How much of an improvement does HDTV provide over DTV/EDTV? The best answer to this question is to walk or drive to your local electronics store and get a demonstration from someone qualified to show you. You may want to have the demonstrator find channels that are broadcasting only in 480p, flip to a 720p or 1080i broadcast. On smaller televisions, you may not notice a huge difference, but it will be noticable. On larger television sets, have them demo the same 480p, to a 720p or 1080i format. It should become more evident that the 720p and 1080i broadcasts are much more sharper and clearer than the 480p format.

So long SDTV, Hello DTV and HDTV

Hopefully this article has helped you better understand the basic differences between SDTV, DTV/EDTV, and HDTV. There are many more technical advantages that DTV will bring to the table over SDTV such as using less broadcast bandwidth to provide the same channel programming; you can use the links provided at the beginning of the article for finding more in-depth information.

As always, please post questions and feedback to this article so that we can better the DTV community. :cool:
 

teresa

DTVUSA Member
#2
I know all this makes perfect sense to you and to my husband who is in the production business, but for someone like me who is not technically minded it's all greek. Honestly, it has never even bothered me to watch a regular screen and I know people are hankering for the wide screen. My husband has pointed out the quality of the picture, say with bue ray versus regular and it is a pretty picture, but still...Maybe I really only care more about the subject matter than the quality of the picture.
 

coryd

DTVUSA Rookie
#3
I don't think this is right.

I understand why the quality of DTV is better, but why is it appropriate for the government to pass a law to force this change. Laws are meant to protect the people of our great country. However, I do not believe they were originally meant to force a technology change, allowing product manufacturers to sell their equipment to a mass number of households. This law does not seem to protect anyone, just fatten a few wallets.
 

Jason Fritz

Administrator
Staff member
#4
I understand why the quality of DTV is better, but why is it appropriate for the government to pass a law to force this change. Laws are meant to protect the people of our great country. However, I do not believe they were originally meant to force a technology change, allowing product manufacturers to sell their equipment to a mass number of households. This law does not seem to protect anyone, just fatten a few wallets.
The law will probably fatten a lot of wallets. Cable and Satellite companies, television manufactures, and converter box manufactures probably stand to profit the most from the digital transition.

The biggest benefit of switching to DTV would probably be to free up some of the current television broadcast spectrum. Digital Television uses less bandwidth, so what's going to happen with the extra unused spectrum?

Here's a quote from the Government's DTV Website:
An important benefit of the switch to all-digital broadcasting is that it will free up parts of the valuable broadcast spectrum for public safety communications (such as police, fire departments, and rescue squads). Also, some of the spectrum will be auctioned to companies that will be able to provide consumers with more advanced wireless services (such as wireless broadband).
 

Fardreamer

DTVUSA Member
#5
I understand why the quality of DTV is better, but why is it appropriate for the government to pass a law to force this change. Laws are meant to protect the people of our great country. However, I do not believe they were originally meant to force a technology change, allowing product manufacturers to sell their equipment to a mass number of households. This law does not seem to protect anyone, just fatten a few wallets.
I'm not an expert on the Telecommunications Act of 1996, but I do believe that Congress did, in fact, mandate a technology shift from analog broadcasts to all digital. (See Jay's post above this one for the rationale) It has been in "in the books" for 12 years, and while it is definitely making millions for manufacturers of HDTVs, cable/satellite boxes, and the new analog-to-converter boxes, it's not exactly "not protecting" consumers.

I think the problem is that the government and the media did not really make much of an effort to explain what the DTV portion of the Telecommunications Act actually meant; most of the public's attention in 1996 was on keeping the cable companies from raising their fees unfairly, if memory serves. Now that the February 2009 deadline is getting closer, everyone seems to be so surprised and almost panicky about it.
 

aclowers

DTVUSA Member
#6
1080i vs1080p


HDTV broadcasts provides more lines of resolution than the standard DTV broadcast. Since DTV has 480p lines of resolution, HDTV can be broadcasted at three different high-definition broadcasting formats: 720p, 1080i, and 1080P.

720p is a progressive scan with 720 lines of resolution.

1080i is interlaced with 1080 lines of resolution.

1080p is progressive scan with 1080 lines of resolution.

In terms of which is the better picture quality, generally you can assume that the higher the the lines of resolution, the better the picture quality.

How much of an improvement does HDTV provide over DTV/EDTV? The best answer to this question is to walk or drive to your local electronics store and get a demonstration from someone qualified to show you. You may want to have the demonstrator find channels that are broadcasting only in 480p, flip to a 720p or 1080i broadcast. On smaller televisions, you may not notice a huge difference, but it will be noticable. On larger television sets, have them demo the same 480p, to a 720p or 1080i format. It should become more evident that the 720p and 1080i broadcasts are much more sharper and clearer than the 480p format.


We bought a HDTV a few months ago. I spent a lot of time trying to decide which one had the better picture. If I was going to invest that kind of money into a television, I wanted to make sure it was what I wanted. I ended up choosing a LG brand 1080p. However, when I got it home and hooked up it was not the same quality of picture. Well, I thought maybe I just needed help with the settings. No, that wasn't the problem. The store conveniently forgot to tell me I had to have a HD box, HDMI cables, etc. O.k. I was frustrated at this point, since the whole reason I bought the t.v. was because of the crystal clear picture I saw in the store. I ended up having to also order HD programming, as well. I didn't appreciate having to spend all this extra money to get the picture that was advertised in the store.

In addition to all this, when Direct TV came out to install the HD box and HDMI cables they told me that stations only broadcast in 1080i, not 1080p. He said they were selling television capable of broadcasting in a higher resolution than the stations were currently set up to broadcast.. Well, in a way I guess it could be a good thing. Hopefully, my television will be good for years to come. I asked why the picture in the store was able to broadcast 1080p, if I couldn't get it. They told me they stores play a video on a Blue-Ray in a loop. Of course, they are nature videos and the clarity is amazing. I just wish they would have told me up front what I would have to go thru to get the picture I thought I was paying for.
 

nick

DTVUSA Member
#7
I bought a Sony HDTV a few weeks ago and i was totally confused to get which one and i am gonna invest so much and is it worth? Yeah i sorted out everything and i got this...
 

Ricardo

DTVUSA Member
#8
I remember seeing "regular TV" a few years ago on a friend's large HD-capable flatscreen TV. I guess the show wasn't in HD, because I saw the lines very clearly.

I suppose that's an example of the explanation above?
 
#9
To me, an old-fashioned guy, seeing two widescreen LCD HDTVs playing side-by-side, one on 720P or 480i, and the other in 1080i or p, i am sorry but i cannot perceive the difference. most if not all widescreen big screens sold here are LCD and have horrific black levels even today, and pardon me if i offend, but i still see my 25" Magnavox console as a really big screen; maybe it's my small home but it's a BIG screen to me. sit even closer and it's even bigger. in DTV mode it has a much nicer picture, even if it is SD, it actually looks better with the nicer black levels and no light glare than a 1080p HD signal. the big disadvantage of HDTVs is they must downconvert to 480i or 720p if the channel isn't broadcasting any better and they are TERRIBLE when they're running in any resolution lower than 1080i. that's the only perceivable diff between my Magnavox Console and a HDTV. the fact my TV looks great on every channel, DVD-quality, yet the HDTV looks like crap in about 1/2 the channels in my lineup.

If your converter box doesn't have a HDMI output, forget even thinking about buying an HDTV. if they are crappy looking in lower resolution HD inputs, you don't want to see how awful the RF-Coax input looks in 480i only.

My confusion is that my TVs are regular old 480i TVs, yet any channel in 480i mode (standard def) has the black bars or even so much as a scaled down portion with a black border around the entire picture. yet the HD broadcasts convert to SD fine and display in full-screen. what gives? i thought it was the other way around? i cannot zoom in on 480i channels and have to be forced to view a smaller picture anyways. does anyone know of a converter that can zoom it full-screen regardless of the channel's aspect ratio?
 
Last edited:
#10
Black Block free picture

I have a Channel Master converter that has a WIDE button on the remote that allows a black block free picture.

A Best Buy converter is a total waste in that regard.

A Magnavox allows a black block free picture on the main channels but doesn't control the subchannels.

Google Bush Nazis or 9/11 Nazis or such and you will understand why we have Nazi-TV.
 
Top