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Thread: Hdtv

  1. #1
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    Default Hdtv

    A survey done by a consumer electronics retailer earlier this year found that almost 90% of respondents don't understand HDTVs and 50% underestimate the cost of buying one.
    The reason so many consumers underestimate the cost is that retailers fail to educate consumers of the two other things you'll need besides an HDTV to watch a high definition televison show.


    High-definition television or HDTV is a television broadcasting system with significantly higher resolution than traditional standard definition television (SDTV).
    If you ask some experts about HDTV, they'll often begin to get into a technical discussion and begin to tell you about 720p, 1080i, 1080p and all sorts of other technical stuff but they'll never explain why you want HD or how to get it!

    Simply speaking, high definition television is a relatively new technology that delivers a superior television image along with superior sound.

    The biggest confusion surrounding HDTV is consumers think they only need to buy an HDTV in order to visualize stunning image quality. Unfortunately that is not the case. In order to watch high definition programming you will need three things: a source for HD Programming, a HD Set top box or tuner, a high definition television set (HDTV).

    It’s important to remember that if you don't have all three you won't be watching HDTV!

    There are different sources for your HD programming. The first is the cable or satellite provider that currently delivers television signals to your home.

    When your favourite television program comes on and the announcer says the show you are watching is being broadcast in HD, it does not mean you are watching HD. When a show is available in HD, it means the networks are broadcasting versions of the show: a standard definition and a high definition version.
    For example, let's say you want to watch CSI which airs in HD .
    With cable or satellite the standard definition viewer would tune to particular channel while the high definition viewer would tune to a different channel . To receive the HD channel cable and satellite customers must first subscribe to an HD programming package. .


    The second method for receiving HD programming is over-the-air (OTA) … which is not the same as satellite. The aerials and rabbit ears you used to receive television signals in the days before cable can now be used to receive HD signals where available. Before you have dreams of dumping your cable or satellite provider, check the number of HD signals that can be received OTA in your area..

    The next step in watching HD is to buy or rent a device that will decode or tune the incoming HD signals. Once decoded, the signals can then be sent to your television in a format your set can display.

    If you are interested in receiving HD signals over the air you will need an ATSC (Advanced Television Systems Committee) tuner also an antenna. An ATSC tuner is simply the Digital equivalent of your existing televisions channel tuner. Most HDTV's sold today include an ATSC tuner, however, be sure to confirm that before buying your HD television.
    1. All OTA antennas are "digital ready" and "HDTV ready" (ignore those marketing words)
    2. Satellite Dishes cannot be used to receive OTA signals because they operate on totally different frequencies
    For many people, to decode and tune HD programs you will need a High definition satellite receiver or HD digital cable set top box. The HD satellite receiver or HD digital cable box takes the encrypted HDTV programming sent by your cable or satellite company and puts it in a format that can be used by your television.

    An HD satellite receiver or a cable HD set top box can often be bought from a major consumer electronics store or rented from your cable or satellite provider. These set top boxes rent for about $20 a month or they can be purchased for anywhere from $200 to $400.

    Before you go and buy an HD satellite receiver or set top box, please note the following:
    • Each satellite company and cable company have their own proprietary set top boxes which typically are not compatible with others. Something to consider if you're trying to decide between buying or renting a satellite receiver or Digital terminal.
    • A regular Digital Cable terminal or Digital Satellite receiver will NOT decode HDTV signals so be sure to look for the a box that specifically states that it is an HDTV receiver or terminal


    There is a third source available now …DVD though there are two formats HD DVD and BlueRay. There is a battle taking place between makers of the two different formats ( sounds like the familiar VHS and Beta war) and yet to be decided as to which is the format of choice.


    Once you have subscribed to HD programming and bought or rented an HD terminal, the final thing you'll need is a high definition television (HDTV).


    What to look for or what type of HD television is beyond the scope of this post. Be sure to confirm that you are buying an HDTV and not an EDTV or Digital television. If the television is sold as an enhanced definition television (EDTV) that accepts HD signals then don’t buy it. EDTV or digital televisions have been marketed as being able to accept HD signals but the truth is they cannot actually display an HD signal. They simply take the HD signal and downconvert it to a less desirable picture.

    EDTV televisions or just plain Digital televisions have pretty much disappeared from the marketplace, however, they are still being sold in the clearance aisle. If the television your are considering is much cheaper than a typical HDTV then its possible you’re getting an EDTV so be sure to ask. If you have any doubts then be sure to check the televisions manual or the companies website to confirm.

    Hope this helps.

  2. #2
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    Default Re: Hdtv

    I don't think I understand you correctly. I have an HDTV with an ASTC tuner and a roof top antenna installed in my attic. I get OTA HD TV shows on the digital channels. I do not have any table top box of any kind. In my area, Memphis, TN, every analog station has one or more digital channels.

    As far as I know, the highest resolution being broadcast over the air is 720p, most are 1080i. Many are much lower resolution for things like a weather channel or music video channel. I.e., channel 5 has three digital channels. 5.1 has the tv programming in a high resolution, usually 1080i. 5.2 is a music video channel and 5.3 is the weather channel, both in very low resolution.

    There is one thing about the digital channels, they are all UHF. The VHF part of the antenna will soon be useless except to serve as a reflector for the UHF portion.

    BTW, I live out in the boonies. I have a satellite dish for internet because we can't get cable or DSL, but I don't use it for TV. I have to use a directional antenna and an amplifier, but all the stations are within a 5° arc of each other so I don't need a rotator.

    One more thing, some EDTV's are better than some HDTVs. The EDTV's go to 720p, but a lot of HDTVs can only go 1080i. At this time, I would recommend that anyone buying a TV get a 1080p even though there are very few 1080p sources right now. With the lifespan of a plasma or LCD tv now expected to be 22 to 25 years, you wont want to be obsolete in 5 years. I bought my last TV in 1988 and the only reason I replaced it was that I got some new equipment that I couldn't plug in to it (DVR). You also want at least two HDMI ports as well as a selection of other types of connections.
    Last edited by keith3267; 12-28-2007 at 10:24 PM. Reason: add another paragraph

  3. #3
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    Default Re: Hdtv

    keith3267 ... maybe it was missed but I mentioned twice you can receive HD OTA providing your TV has an ATSC tuner.

    To summarize :

    method 1 - is through a cable or satellite provider

    Method 2 - is OTA either with a set top box ( if needed) or through a built in ATSC tuner and providing there is HD broadcast available.

    Method 3 - is either HD DVD or BlueRay DVD



    Hope this clarifies things.

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    Default Re: Hdtv

    Not to go too far from the scope of things I thought to mention a few things regarding EDTV. Just to clarify they are not terrible units just that anyone looking at current to future needs should really consider a HDTV instead.

    A standard television screen is comprised of about 480 scan lines. this type of display is referred to as interlaced, or 480i. It is also called 525i because there are 45 additional "blank lines" built into every frame transmission to give the display time to reset itself. Nevertheless, the proper designation is 480i, or standard definition TV (SDTV). This technology was fine for smaller screens, but as displays became larger the 480 scan lines became visible Simply put, large screen TVs only magnified SDTV's shortcomings.

    Enter progressive scanning.

    A progressive scan TV paints the entire frame in one sequential pass, eliminating much of the distortion that two-pass interlacing creates. Although the TV still receives the video frame in two parts, it combines the data before painting it by using an internal processor called a deinterlacer, also known as a line doubler. Progressive scan displays are specified as 480p or 525p, more commonly called enhanced definition TV (EDTV).

    EDTV equates only to the resolution of a wide-screen DVD (852x480 pixels), EDTV represents a significant step forward in display technology, creating a much finer picture than interlaced SDTV.
    EDTV also features a 16:9 aspect ratio, which means the display is rectangular or theater-shaped. And when a DVD with progressive scanning is played looks great on EDTV.

    Though a quality EDTV looks closer to a HDTV than it does to standard television, the HDTV will outshine the EDTV when it comes to high-definition broadcasts by adding more scan lines for finer resolution and more clarity. If a HD source is displayed on EDTV, the signal is down-converted to 480 lines in order to display it, and in the process some of the extra clarity is lost.

    While EDTV has 480 scan lines, HDTV supports two high-definition broadcasting formats: 720p and 1080i. 720p is a progressive scan with 720 scan lines, while 1080i is interlaced with 1080 scan lines. Generally speaking, the more scan lines, the better the resolution, particularly when considering large screens.

    Typically 720p is preferred for broadcasting shows that involve continuous fast motion … so …. football games and other sports are broadcast in 720p, while "normal" HD broadcasting is typically 1080i. HDTVs will accept either format and do a good job of displaying them, and most people won't be able to tell the difference between the two. They are both significantly clearer and more breathtaking than the 480 scan lines of EDTV.

  5. #5
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    Default Re: Hdtv

    There is certainly a misconception about the old interlace standard. A lot of people think that the picture is a 480 line picture transmitted in two parts, that is not true. It was a 240 line picture transmitted twice. The cameras of the period were only able to capture a 240 line picture every 1/30th of a second, but it was transmitted twice in that timeframe to reduce visible flicker on the TV set.

    The blank lines are the flyback lines and are blanked out. That is the lines that occur while the vertical deflection is moved back to the bottom of the screen. When you divide 525 by 2, you get 262.5. That makes every other first scan start in the middle of the screen, effectively moving it up a half line.

    I have not been in the business for some time so I don't know what a digitally modulated broadcast signal looks like. I'm not sure where you would find this information either. I'm talking about a source that has editorial oversight or peer review, not someone's rambling on a blog somewhere.

    Many HDTV's sold today only have a vertical resolution of 768 lines. There is not the half step from the old analog format so you are not going to get 1080 lines on that screen. Is a 1080i a 1080 line picture where every other line is broadcast on the first pass, then the rest on the second? I don't see how that would give a sharper picture than 720p on a 1080i HDTV set. I can see where it would be sharper on a 1080p HDTV though.

    I stand corrected on EDTV, it has been awhile since I've seen one on the shelf and for some reason I thought it claimed 720p.

  6. #6
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    Default Re: HDTV

    keith3267 ... thanks for the feedback.

    Oh yes the description of the scan , vertical/horizontal retrace lines for the SDTV does bring back memories. I didn't feel the need to detail how all this works but you did a fine job.

    Here's a link that might be interesting to you : http://www.cnet.com/4520-7874_1-5137915-1.html


    Here's another more generic informational link : http://electronics.howstuffworks.com/hdtv.htm

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    Default Re: Hdtv

    I read both links and neither goes into the kind of detail I like to look at. Both also had what I strongly suspect is misleading information or misinformation.

    The CNET article said something to the effect that 1080p wasn't necessary. Now it may have been written some time ago, and in this field, things move very fast. I think though we are coming to a plateau of sorts, that things will become standardized and it may be many years before a breakthrough in technology occurs that would obsolete everything we have today.

    I think the next significant change will be LED TV's, but they will still be using the same sources as the LCD and plasma's. I think the first change will be LED lit LCD's replacing Fluorescent lit LCD's and when the technologies permit, LED direct.

    While 1080p is not absolutely necessary today, I would highly recommend it for any buyer. If you don't have the money right now and you have a working TV at home, then wait. The prices will come down and you can save up. Some new TV's are rated for a life of 60,000 hours, so you need the TV to keep up with the technology for as long as possible.

    When I first started looking for a new TV, a 1080p was out of the question, over $5k. A year later they were down to around $3500 and many came with two or more HDMI ports. I must confess that I didn't know what HDMI was or that anything else used it. By the time I finally did purchase a new set, the 1080p sets 46-47" size were dipping to around $2k, my threshold. Lately, I've seen them for quite a bit less.

    One of the statements in How stuff works stated that "A digital signal transmits the information for video and sound as ones and zeros instead of as a wave." It is transmitted as ones and zeros, but it is still a wave. All broadcast signals are transmitted as a wave, its just digitally modulated. There are a lot of schemes for digitally modulating an analog signal. Some of the early schemes were FSK (frequency shift key) which was like FM except instead of changing the frequency of the carrier with the amplitude of the intelligence, the carrier would switch frequencies suddenly.

    Each of these frequency shifts represented a one or a zero and the rate of change, or the number of changes per second was the baud rate. Later schemes came along that yielded more than one bit per baud, for example phase shift keying yielded two bits per baud. More sophisticated schemes followed cramming even more bits per baud, up to 32 bits per baud (maybe more now) in DSL.

    I'm sure digital TV has take this technology to a new level.

    What I am curious about is how many native lines are there in a 1080i source. Are there really 1080 lines, of which half are broadcast with each frame or are there only 540 lines and each frame broadcast twice. If its the former, then a 1080i will never get the full resolution of the picture. If its the latter, then I'm pretty sure that a true 1080p broadcast signal will be coming in the near future. BluRay is all ready there and HD DVD will soon be.

  8. #8
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    Default Re: Hdtv

    keith3267 ... it's hard to find the more technical details that you would like though it's out there somewhere.... maybe in some hardcore HD forum somewhere.
    Besides it's beyond the scope of things here.

    Just another link you might interesting : http://www.pcworld.com/article/id,12.../article.html##

  9. #9
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    Default Re: Hdtv

    I just thought I'd chime in on this discussion, I work for a Cable company that is making the change to an all digital network. My suggestion on digital boxes is this, don't buy one until you absolutely have to. The government is now mandating that cable co's must provide analog service to those customers who need it. So, if you subscribe to a cable provider now, chances are that they will, in part at least, cover your box charge.
    Also, the government will be providing coupons to offset the cost of these converter boxes, http://www.ntia.doc.gov/dtvcoupon/
    Households can qualify for two $40.00 coupons. I would not use these until you are aboslutly sure what format you need, and when it will be in place. Many of these boxes run over $100.00 now, my bet is they will be around $40.00 to $50.00 by the time you actually need one.

    On another note,I agree with Keith on buying a 1080p TV, most HDTVs are now days, and the price difference is minimal. That being said, I read a lot of tech garbage, and have noticed that a lot of reviews on 1080p are coming up pretty lackluster. Most anyone (including the tech geeks) could not tell the difference between a 1080p picture and a 1080i picture right next to each other. That may very well change, but don't trade in your 720p/1080i for a 1080p TV just yet.

  10. #10
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    Default Re: Hdtv

    Venkman,

    I guess we pretty much agree on most points. I think the reason the tech geeks may not have been impressed with 1080p is there isn't much available in 1080p format. It looks like 1080i only has 540 lines broadcast twice and most 1080i sets also take 720p. I would never recommend that someone change their TV everytime an new feature becomes available, but if you are getting a new TV anyway, then I'd recommend getting the 1080p just to hedge against the future.

    BTW, soon after posting my last reply above, I saw on the Today show that paper thin screens are coming out this year that or organic LED's. The first ones will only be 11" and will be very expensive.

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