Bruce Jacobs is Chief Technologist for Twin Cities Public Television in Minnesota. He's a real leader and communicator within the public television engineering community. Bruce wrote this guide (click Continue reading "How To Buy A TV" below) after making a similar presentation to the TPT staff. Very useful. --Dennis
Also see Digital Television 101 01010101 by Henry Ruhwiedel of WYIN.
This posting has been by far the most popular ever added to this weblog. One common response has been a request to define the acronyms used. For this, I suggest consulting the excellent Crutchfield Advisor TV and HDTV glossary.
And on the subject of how to properly view HD, see HDTV viewing distance, screen height. Link: Technology360.com. --Dennis
HOW TO BUY A TV
Bruce Jacobs - July 2004
TV buying is much more complicated than it used to be.
In the past 50 years, there haven't been many features to pick from, and once optional things like UHF tuners, remote controls, color, stereo and cable channel tuning have all become standard. The main constant over the years was a choice of picture size.
Now, there are SIX different decisions to make and the choices within decisions keep changing. This confounds even the experts. So don't feel alone in your quest!
In the last few years, available displays have gotten much larger and of higher quality, at ever lower costs.
It is now possible to buy a 82" rear-screen projector-in-a-box that light weight and just two feet deep. Affordable high quality projectors are available that can be used to fill a wall-size screen in a dark "home theater".
It's worth having a screen this big, because the increased quality of progressive scan DVD and HDTV cable/satellite/off-air receivers makes it worth blowing the image up this large.
Full HDTV can only be appreciated if the screen is large enough. If you measure your viewing distance from the screen and divide by three, the screen height must be at least that big. This requires only a 17" screen if you are within a couple of feet at your desk, but a very large screen if you are 12 feet away on the living room couch! So, if you are convinced you want a modest screen size in a big room, the extra cost for HDTV resolution may not be worth it.
This term is over-hyped and nearly meaningless. There are analog displays described as "digital" because they can be connected to an HDTV "digital" source, even though they don't have a digital input and there is nothing "digital" in them except the remote!
There are displays that use digital LCD, DLP or plasma technologies that can rightfully use this term, but it doesn't necessarily make them better than an analog CRT.
Newer large displays typically have the new DVI connector which is an actual digital connection. (This connector is also found on newer PCs - it's about ½ X 1-1/2 inches and has many pins.) DVI is better than the three separate YPrPb "Component" connections used on progressive-scan DVD and analog HDTV device outputs.
Finally, displays with actual digital cable and digital off-air tuners are starting the show up in the market, mainly because the FCC forced the industry to do this. When a salesperson says "it's digital", you have every right to ask them "what do you mean by that"?
All true HDTV material and many DVD's are in the wider 16:9 aspect ratio, just like most movies. If that's what you are mainly watching, it's good to have a screen to match.
If you are mainly watching news and daytime shows, it will be a while before these shows are widescreen, so you may want to stick with the traditional 4:3 shape, especially in smaller screen sizes.
This is confounding. The Industry created the terms SDTV (standard definition) EDTV (enhanced definition) and HDTV (high definition) to describe three levels of resolution quality.
To be called "HDTV", a digital display is supposed to have a native resolution of at least 1280 X 720 pixels. A CRT "HDTV" display (front or rear-screen) must work when hooked up to an HDTV signal.
To be called "EDTV", the display must have a progressive scan input (those three YPrPb jacks found on most DVD players.)
While local retailers obey these rules, not all online vendors do. And, just because a CRT makes a picture with an HDTV signal doesn't mean it actually produces this resolution on the screen. Early CRT "HDTV's" didn't even come close. The newer ones get much closer, but are still less than half the potential resolution of full HDTV.
See the rules under "screen size" above to make sure you have a display big enough to benefit from HDTV resolution, in your viewing situation. Buy at least EDTV to support progressive scan DVD's. Buy HDTV to enjoy digital HDTV broadcast, cable or satellite. Soon, there will be HDTV DVD's as well!
DISPLAY TYPES - 36" DIAGONAL AND SMALLER
Direct view CRTs remain the lowest cost and are capable high quality, although not the highest resolution. In the larger sizes, they get very heavy and are very deep - sticking out from the wall.
Direct view LCD displays are becoming much more popular, higher quality and the prices are dropping rapidly. They have the advantage over CRT's of being bright, low weight, and thin.
DISPLAY TYPES - 36" DIAGONAL AND LARGER
Plasma Displays have the advantage of being bright, thin, and available in large sizes. Their disadvantage is the high cost and need to avoid leaving them on channels with constant images like banners for long periods of time, because the image can "burn in". They can also dim over time.
Direct view LCD displays are becoming available in larger sizes, overtaking plasma in some cases with the same advantage of being very thin.
Rear Screen CRT projectors remain popular and are low cost, but have a number of disadvantages: The box is heavy, tall, and deep. The display is not very bright, the resolution not that good, and the picture degrades over time as the components age. Avoid them.
Rear Screen LCD and DLP projectors are rapidly replacing rear screen CRT because of their higher resolution and brightness, lighter weight, smaller box size, and decreasing manufacturing cost. They both need a light bulb to operate, but initial concerns are being overcome by extremely long-life metal halide lamps. However, this is not the kind of display you should leave on all the time.
LCD and DLP projectors are now available in low-cost, high brightness, small size and low noise models for home theatre installations. However, you need a room that can be made as dark as a movie theater in order for the pictures to look good.
DTV Tuners - Most HDTV and digital displays do not include a digital tuner! Instead, you need buy a stand-along set-top-box. (these are often hidden in the store- sometimes combined in a box that also receives DirecTV.)
Fortunately, this is changing with the FCC mandate that all 36", 25" and 13" displays with analog tuners also include a digital tuner by 2005, 2006 and 2007 respectively.
Early digital tuners did not perform well in conditions of ghosting. Fortunately, the 5th generation decoder chips have dramatically improved this situation, and should become available starting in the spring of 2005.
Plug and Play - Today, you need to get a special HDTV box from your cable company or satellite provider to receive HDTV. This box is incompatible with over-the-air digital transmissions.
Finally, the consumer industry is getting ready to deploy digital tuners which can receive BOTH digital cable signals and over-the-air digital transmissions. A security card plugs into these boxes to enable various tiers of digital cable programming. You'll begin to see this feature included in many of the FCC-mandated off-air tuners included with displays.
Connection Confusion - With all these new set-top-boxes and display connection formats, hooking up a home system can be a daunting task.
HDTV Recording - Today, there are only a few models of digital VHS recorders available. These are able to record HDTV programming at full quality, but only from off-air sources. There are HDTV "Tivo"-like personal video recorders available for cable and satellite reception.
Screen Size - Get the largest display you can afford!
34" or Smaller - Consider HDTV LCD or CRT if close to the screen
34" or Larger - Go HDTV widescreen and avoid rear-screen CRT.
Under 50" - Favor LCD over Plasma
Getting HDTV? - Ask for DVI input connector.
Want a DTV Set Top Box? - Wait for 5th generation devices in 2005.