|
|
Shopping for a new TV? The HDTV buying guide will introduce you to some helpful tips on what to look for and what current technologies are available.
|
|
• HDTV Basics
• What should I look for in a HDTV?
• HDTV Resolution
• HDTV Display Technology
• HDTV Brands
• HDTV Glossary
What is HDTV?
HDTV stands for high-definition television, and it marks the biggest leap forward for television since color TV made its debut.
HDTV images are more than twice as detailed as standard analog TV, delivering rich images, as well as multichannel, movie-theater-quality surround sound.
HDTVs can display both regular and HDTV images, but they need HD signal sources to look their best. All HDTVs are digital TVs,
but not all digital TVs are high-definition televisions. High Definition (HD) is defined as picture detail (video resolution) of 720 lines or 1080 lines.
In comparison, our old analog TVs were a maximum of 480 lines. So you can see that High Definition TV (HDTV) has much more picture detail and therefore much sharper images on your TV screen.
How much do HDTVs cost?
Back in 1999, you couldn't buy an HDTV set for less than $5,000. Only early adopters with plenty of money were buying HDTVs at that time.
In the last few years however, prices have dropped dramatically. For under $500, you can pick up a smaller LCD TV that's capable of displaying HDTV images.
That said, you will pay up to $3,000 for the larger size screens on an HDTV. Most buyers want a screen size of 32 inches to 50 inches. The 32 inch HDTVs cost about $700 to $800, the larger 40 inch models about $1,400 and the 50 inch models about $2,500 depending on the model, brand, and features. So you can see that costs have gone down but if you want a good sized TV, you will still be paying a substantial amount for the larger Plasma and LCD TVs.
What kind of HDTV should I buy?
The right HDTV for you depends on your budget, the size of screen that you want and the type of display technology you think looks best in your viewing room. For a small room such as a kitchen, a smaller LCD TV is a good choice. For larger rooms, you'll want at least a 32-inch or larger set to appreciate the detail of HDTV. A 42, 46 or 50-inch display can be impressive. Display technologies consist of Plasma, LCD, CRT, Rear and Front Projection.
Plasma and LCD HDTVs offer a flat-panel profile with bright, sharp, direct-view images. Both flat-panel TV types (LCD and plasma) save space and can be mounted on a wall. Sizes can go up to over 100 inches. CRT, the old tube technology, is available in the 34-inch screen size range if you prefer to stick with the old TV display type and do not want a hugh screen. Rear-projection set, you may see them referred to as DLP, LCD or LCoS rear-projection, are bulkier than a flat-panel TV and use a lamp and a lens to display images on the screen indirectly. Front-projection TV or, more accurately, a home-theater projector, can fill a 100-inch-diagonal screen using a lamp and lens. The projector can be hidden in the ceiling and the screen can be rolled up into the ceiling out of view when not in use.
Digital TV signals can be transmitted in various video resolutions, some of which are not high definition. Only if your television signals are 720 or 1080 video resolution are you getting HD. The main point here is that it doesn't do you any good to have an HDTV if you don't have HD signals coming in to your television. HD signals are available over the air from local broadcast TV stations, from cable TV providers and from satellite TV providers. Broadcast TV is free, you just need a good VHF/UHF antenna to pick it up. Cable TV and satellite TV are not free and you need the provider's converter set-top-box to de-scramble their signals.
HDTV Features
With an HDTV you are getting a leap forward, in many aspects, from the old analog TV sets.
Some of the added features you'll enjoy include much larger display screens which are wider,
brighter and have sharper detail. With a "Full HD" 1920 X 1080p display panel and built-in digital ATSC tuner, HDTVs can deliver an ultra sharp, large-as-life widescreen true HD picture, HD media connectivity, Dolby Digital sound, SPDIF audio output and can double as a PC display. With multiple HDMI inputs you can hook up all your digital gear such as Blu-ray Player, video games, DVR, Cable TV or Satellite TV set-top-boxes.
What should I look for in a HDTV?
Screen Size
Measured diagonally across the screen, look for an HDTV which fits your viewing room.
Consider the distance you sit from the TV as well as the size of the room. A 50 inch flat panel may be inappropriate for a small bedroom.
Popular screen sizes go from 26 and 32 inches up to 42, 46 and 50 inches which are large enough for most viewers, up to 60, 73 and even over 100 inches. Keep in mind that the larger the screen size, the heavier the TV.
Aspect ratio
16:9 - Your HDTV should have a 16 to 9 aspect ratio. This is a widescreen (more width than height) TV for showing movies in their intended panoramic full view format.
Panel resolution
1920x1080p - a native resolution of 1920 by 1080 gives you pristine "Full HD" video at the highest levels. Other panel resolutions are 1366x768 which would be good for 720p video.
Contrast ratio
(typical) 1200:1 - Be careful here. Contrast ratios are not all measured using the same standard. The contrast ratio is a measure of a display, defined as the ratio of the luminance of the brightest color (white) to that of the darkest color (black). A high contrast ratio is a desired aspect of any display, but with the various methods of measurement, remarkably different measured values can sometimes produce similar results. Dynamic contrast ratio measures the luminosity of the brightest white and the darkest black the television can produce at two different instants in time. Contrast ratios of 10000:1 are not uncommon.
Brightness
500 cd/m - 1500 cd/m The higher the number the brighter the picture.
Brightness is measured in candela per square meter, the standard unit of luminance and is a measure of light intensity.
Luminance is quoted when specifying the brightness of displays. Cathode-ray tube (CRT) generally provide greater luminance than thin-film transistor (TFT) displays.
However, the best criterion for choosing and adjusting a display is the user's own viewing comfort.
Response time
(typical) 8 ms. Slow speed can add unwanted blur to fast-moving objects on the screen. This can be particularly noticeable when a bright object is moving against a dark background, or vice versa. 8-millisecond switching speed keeps up with the most demanding video content. Sports, action movies and video games are sharper, crisper and more lifelike with response times in the 4ms to 8ms range.
Viewing angle (H / V)
176 / 176 degrees. (The maximum is 180 degrees) The wider the viewing angle, the better the picture will look to people sitting to the extreme left or right of the TV. The optimal viewing angle for any TV is straight ahead.
HDTV Compatibility
480i, 480p, 720p, 1080i, 1080p
Tuners: ATSC/NTSC/QAM built-in to TV
An ATSC tuner is required to receive over-the-air broadcasts from local digital TV stations.
A QAM tuner is required for Cable TV. You may also need a cable set-top-box.
An NTSC tuner is required to receive over-the-air broadcasts from local analog TV stations.
For satellite TV, you will need a set-top-box from your satellite TV provider
VESA wall mount compatible
400 x 200 mm - Your HDTV should be VESA (Video Electronics Standards Association) compliant. VESA is a standard which defines the hole patterns on the back of HDTVs so owners know which wall mounts will fit their TV. 75 mm x 75 mm or 100 mm x 100 mm are common.
Learn more about it.
Weight
68 lbs., 100 lbs. How much can you handle? Consider how heavy the TV is, some can weigh more than you think.
On-screen Menus
Make sure the user menus are easy for you to navigate. You will need to change settings eventually.
Extras
Check out the TV speakers. How does the audio sound to you?
Does the TV have external speaker hook ups? Does the TV have a digital audio output (coaxial or optical) for sending surround sound to a audio/video receiver? Does the TV have a PC port? The PC port is usually blue and is called D-sub 15-pin for PC input from your computer.
This way you can use your bigger HDTV display instead of your computer monitor.
Connections
You want a TV with as many ports as possible. Make sure the TV has at least two HDMI inputs and two component video (green, blue, red) inputs.
If you want to connect a VCR, DVD recorder or game console, you will want composite video (yellow) and audio (red and white) inputs.
Learn more about it.
|
|
|
Resolution, or picture detail, is the main
reason HDTV programs look so good. The standard-definition
programming most of us watched for so long on our analog TV sets, has at most 480 visible lines of
detail, whereas HDTV has as many as 1,080. There are three common HDTV resolutions, called
720p, 1080i and 1080p. One is not necessarily better than the other; 1080i has
more lines and pixels, but 720p is a progressive-scan format that
should deliver a smoother image that stays sharper during motion.
At the top currently is 1080p, which combines the
superior resolution of 1080i with the progressive-scan smoothness of
720p. True 1080p content is rare outside of Blu-ray and the
latest video games and none of the major networks has yet
announced 1080p broadcasts. Look at the comparison chart below to see the differences. |
|
|
|
| Name |
|
Resolution |
|
HDTV |
|
Wide-screen |
|
Progressive-scan |
| 1. 1080p |
|
1,920x1,080 |
|
Yes |
|
Yes |
|
Yes |
| 2. 1080i |
|
1,920x1,080 |
|
Yes |
|
Yes |
|
No |
| 3. 720p |
|
1,280x720 |
|
Yes |
|
Yes |
|
Yes |
| 4. 480p |
|
852x480 |
|
No |
|
Yes |
|
Yes |
| 5. Analog TV |
|
Up to 480 |
|
No |
|
No |
|
No |
|
Native Resolution
Every HDTV has a native resolution.
Native Resolution is the number of physical pixels in a display device. For example, an XGA display has a native resolution of 1024 physical pixels of resolution horizontally and 768 pixels vertically or 786,432 total pixels.
An HDTV with a native resolution of 1,920 by 1,080 can display 1080p video sources without any "scaling" or video manipulation.
An HDTV with 1,366 by 768 native resolution would have to modify the original 1080p source or "down-scale" in order to display it.
The point here is that you want your HDTV to have a native resolution as close as possible to the video sources you are going to be viewing.
HDTVs will up-scale or down-scale video to match native resolution without any problem, however you want your viewing to be as pure as possible. You can check the HDTV you plan on buying to see what the native resolution is by
looking online at sites that sell that model, at the owner's manual or on the manufacturer's website. Sometimes a retail store will list the native resolution of HDTVs they have on display.
|
Currently there are five common HDTV display types.
They are CRT, LCD, Plasma, Rear-projection and Front-projection. LCD and Plasma are the most popular display types. The large wide-screen flat-panel design is perfect for wall mounting and gives bright colors with high contrast and in High Definition, crystal clear, sharp images. These modern flat-panel TVs have digital TV tuners built in for over-the-air broadcasts (ATSC) and many also have cable TV (QAM) tuners for non-scrambled cable channels.
LCD and Plasma TVs use different technologies to display video and therefore have somewhat different characteristics.
In a same size screen comparison, Plasma will use more electricity (and therefore create more heat) and be heavier than LCD.
Some electronics companies have stopped making Plasma sets in favor of LCD. Screen sizes of 26 in. up to 50 in. are very popular. The cost for a LCD or Plasma HDTV vary from a low of $600 up to $3,000 and more.
LCD HDTV
How does a LCD (Liquid Crystal Display) work?
LCD flat-panel displays typically measure around 4" in depth, and like plasma they can be mounted on a wall.
On a flat-panel LCD screen, a backlight streams high-intensity white light (provided by a series of fluorescent tubes behind the screen surface) through tiny cells filled with a liquid crystal material.
Each pixel has three such cells one each for red, green and blue components of the signal. When an electrical charge is applied to the liquid crystals,
their molecular structure shifts, modulating the intensity of the light that passes through to the screen.
Unlike plasmas, which start at 37 inches and go up from there, LCD TVs are available in smaller sizes, from 5" handheld models to widescreen HDTV models of 26, 32, 42, 46, 50 inches or more.
Slim, sleek and lightweight, LCDs can be placed or mounted almost anywhere in the home, including places where you might not have considered placing a TV ? and, in fact, can easily be transported from room to room (with the exception of the largest screen sizes). LCD technology produces an exceptionally bright picture and unlike plasma, the matte screens of LCD sets don't reflect much ambient room light, so they're generally better suited to very bright rooms. LCD TVs can make very good big-screen computer monitors.
Due to the unintended leakage of some light to the display, many LCDs cannot produce as deep of a shade of black as most plasmas. On the other hand, some newer LCD models with adjustable backlights can actually produce deeper blacks than plasmas. LCD backlights can also cause less-even uniformity than plasma, leading to slightly brighter corners or sides, for example, than the middle of the screen. Most newer models have greatly improved performance and don't suffer from visible blurring during quick motion such as sporting events.
The choice between LCD and plasma is a matter of personal taste, size and cost. Each has its advantages and disadvantages.
Plasma HDTV
Plasma was the first flat-panel technology in widespread use. Plasma displays function differently from LCD TV technology in that they produce light independently at each pixel on the screen. A plasma screen is actually a network of individual cells, three for each pixel of the display coated with red, green and blue phosphors, respectively.
Each cell contains a rare-gas mixture and is connected to an individual electrode. When the electrode for a given cell is charged with an electrical voltage, the gas is converted to a plasma state and emits a burst of ultraviolet light; this in turn causes the phosphors to react and produce bright visible light at the pixel level. By varying the voltage and intensity of the electrical charge, the proper combination of red, green and blue light is produced in each pixel to combine into a composite image. Plasma TVs are big ? they're available in sizes from 37" up to more than 60".
Plasma TVs are desirable for their sleek form factor ? about 4" deep and wall-mountable. Plasmas can get just as bright as flat-panel LCDs, and many produce superb color accuracy and saturation along with a deep shade of black. Compared to LCD, plasmas' light output and color are typically more uniform across the entire screen surface, and plasma screens can be viewed from any point off-axis without a detrimental effect to the picture quality.
In certain situations, plasma TVs can experience a problem known as "burn-in," where the faint outline of a static image left on-screen for hours at a time remains visible after the image changes. Plasmas are most vulnerable to burn-in during the first few months (100-200 hours on-time) of ownership, during which time it's best to avoid static images for long periods, say 6 straight hours or more. After that initial phase plasma phosphors become broken in, burn-in occurs less frequently, and plasmas become just as reliable as other TV technologies.
The exterior glass screens of plasma TVs typically reflect more ambient room light than the matte plastic screens of LCDs, so you may occasionally see yourself reflected in the screen during a dark scene, for example. If you're bothered by this issue and can't control room lighting at all, you may opt for a plasma with an anti-glare screen or just go with an LCD TV.
HDTV Brands
Generally speaking, the best HDTVs are made by Sony, Samsung, Sharp, Panasonic and Pioneer.
You can buy a bargain brand such as Vizio or Westinghouse but if you want to integrate the TV with the rest of your Home Theater devices, you are better off with Sony and Panasonic because they also make the audio/video receivers and other gear which are designed to be coordinated electronically with the HDTV and remote control.
HDTV Jargon
Not sure about all the technical mumbo-jumbo when it comes to digital television or choosing a high definition tv? Here are many of the terms you will hear tossed around.
1080i
1080i is a high definition 1920 x 1080 interlaced video format where a frame of video is delivered in two fields. The first field contains the odd lines of the image and the second field contains the even lines. Each field is updated every 1/60th of a second resulting in 30 frames of video per second.
1080p
1080p is a high definition 1920 x 1080 progressive scan video format where a complete frame of video is delivered at either 30 or 24 frames per second.
480i
480i is a Standard Definition Television (SDTV) 702 x 480 or 640 x 480 interlaced video format where a frame of video is delivered in two fields. The first field contains the odd lines of the image and the second field contains the even lines. Each field is updated every 1/60th of a second resulting in 30 frames of video per second.
480p
480p is an Enhanced Definition Television (EDTV) progressive scan video format where a complete frame of video is delivered at either 60, 30 or 24 frames per second.
720p
720p is a high definition 1280 x 720 progressive scan video format where a complete frame of video is delivered at either 60, 30 or 24 frames per second.
8-VSB
The modulation technique used in the U.S.A. for broadcast (over-the-air) digital television. 8 level Vestigial Side Band. Amplitude Modulated (AM) broadcast system developed to carry the MPEG 2 transport stream(s) of Digital TV at 19.2 Mbs. Uses the same 6MHz bandwidth as an analog channel does but more efficiently.
Analog TV
An analog TV cannot display progressive-scan DVD or HDTV. It can however be used to display converted TV signals from digital to analog using a converter box.
SDTV
Standard-Definition TV. This is the lowest resolution video and is NOT high definition.
EDTV
Enhanced-Definition TV. Falls between SDTV and HDTV. Usually refers to 480p video. It is progressive scan but NOT high definition.
HDTV
High-definition televisions, or HDTVs, can display standard TV,
progressive-scan DVD, and HDTV signals. They are by far the most common
type of digital television.
Aspect Ratio
The ratio of image width to image height. Standard television is 4:3 or 1.33:1, that is, 4 units wide by 3 units high which is a rather square screen. Panavision or Cinemascope is 2.35:1 with 1.85:1 being quite common as well. HDTV Widescreen displays are 1.78:1 or 16:9 ratio, that is, 16 units wide by 9 units high which is a more rectangular screen.
ATSC
Advanced Television Systems Committee. The digital television standard used in the U.S.A. for broadcast TV in SDTV and HDTV formats. Formed in 1982, this international committee develops voluntary standards for terrestrial digital television. Countries adhering to its standards include Canada, Argentina, Mexico, South Korea and the U.S.A. ATSC Digital TV Standards include HDTV, SDTV, data broadcasting, multichannel surround audio, and interactive television. HDTVs have ATSC tuners built-in to them in order to receive broadcast digital television signals from local TV stations.
Bit Rate
Measured as "bits per second," and used to express the rate at which data is transmitted or processed. The higher the bit rate, the more data that is processed and, typically, the higher the picture resolution.
Backlight
LCD TVs use a light behind the liquid crystals which should last for many years. Rear-Projection TVs such as DLP use a lamp which may need to be replaced eventually.
Blu-ray
An optical disc format for high definition video up to 1080p resolution and multi-channel audio. Uses a blue-violet laser to read the disc as opposed to the red laser used in standard DVD. Blu-ray Players can also play standard DVD-Video.
Color Temperature
Color temperature is a way of measuring and describing the color quality of white light by comparing it to a theoretical black body heated to a specified temperature on the Kelvin scale. It's important in the design and use of HDTV's, computer monitors and digital cameras. Every time we watch a TV, use a computer monitor, take a picture or look at a photograph, our brains adjust the colors we see so that they look the way we think they ought to. Color temperature is a useful way to describe the whiteness of white light, especially when comparing one light source to another.
Component Video
An analog cable interface that is capable of transmitting digital HDTV signal. The video signal is sent in three pieces: one cable is used for luminance while the other two are used for color. This is the lowest quality interface for an HDTV signal.
Contrast Ratio
This refers to the difference in brightness from full brightness and black. If a unit puts out 300 cd/m? (candelas per square meter) at full brightness and 0.3 cd/m? when black the vendor will divide 300 cd/m? by 0.3 cd/m? to get a 1,000:1 ratio. Some manufactureres will measure dynamic contrast ratio, in which the unit will analyze the signal and adjust the backlight to create an even higher contrast ratio.
DLP
DLP (Digital Light Processing) is a commercial name for a display technology from Texas Instruments (TI). The technology inside is often referred to as DMD (Digital Micro-Mirror Device). It consists of an array of mirrors where each mirror represents a pixel element. For example, a high-definition DLP projector or rear projector with 1920 x 1080 pixel resolution would have over 2 million tiny mirrors. Each mirror is attached to an electronically driven hinge that controls the amount of colored light that is reflected from the mirror into the projection lens and onto a screen. TV Projection systems using DLP technology use 1 to 3 DMD devices. DLP HDTVs are typically rear-projection TVs unlike LCD and Plasma which are direct-view televisions.
Dolby Digital
A lossy compression system to deliver sound on DVDs, ATSC and DBS TV broadcasts in up to 5.1 audio channels. Also called AC-3 and Surround Sound. When TV shows are sent with Dolby Digital 5.1 audio, your HDTV can send the audio bitstream out to a DD5.1 audio/video receiver which can decode, amplify and route each audio channel to a loudspeaker surrounding the listener. There are also 6.1 and 7.1 systems but content comes mainly from Blu-ray Discs.
DVB-T (Digital Video Broadcast ? Terrestrial)
The digital television standard that encompasses SD and HD formats in many other parts of the world other than the United States.
DVR
Digital Video Recorder - usually uses a hard disk to record television audio and video. Can be incorporated into a set-top-box with a tuner/decoder.
HDCP
HDCP (High-bandwidth Digital Content Protection) is a method for protecting copyrighted digital content that uses the HDMI (High-Definition Multimedia Interface) by encrypting its transmission between the video source such as a set-top box, DVD player, or computer and the digital display device such as a projector, monitor or television. To view digital HDCP protected content, both the sending and receiving device must support HDCP.
HDMI
HDMI (High Definition Multimedia Interface) is an uncompressed, all-digital audio/video interface that supports audio/video sources such as a set-top box, DVD player, A/V receiver, and video monitors such as a digital projector or digital television (DTV). HDMI supports HDCP. HDMI has undergone several revisions so always check your devices to ensure compatibility and capability. HDMI cables have typically 19 pin connectors and cost more than standard audio or video cables. HDMI connections ae used between devices to keep the signals all digital.
HDMI supports standard, enhanced, or high-definition video, plus multi-channel digital audio, and interactive controls on a single cable. It transmits all ATSC (Advanced Television Systems Committe) HDTV standards and supports 8-channel digital audio. First product releases using HDMI occurred in 2003.
HD STB (HD Set-Top-Box)
An external box that incorporates a high definition digital tuner.
HDTV (High Definition Television)
A range of standards for digital television broadcasts including: 720p (1280 x 720 progressive scan) and 1080i (1920 x 1080 interlaced).
Integrated HDTV
A television with a high definition digital tuner built in.
Interlaced
Interlaced formats, like SD and HD 1080i, show half the total horizontal lines in each frame. This means all the even numbered lines will be drawn in one frame, and all the odd numbered lines in the next frame. Interlaced formats are not as high quality as progressive scan formats at the same resolution.
MPEG-2
The standard data compression format for Digital TV, DVDs and Digital satellite TV, among others. Uses same techniques as MPEG-1 but adds support for interlace video and multichannel sound as well as offering higher bit rates.
MPEG-4
An audio/visual file format that is designed for multimedia applications. It allows for other types of media such as 3D objects as well as video and offers interactive capabilities. It is a more efficient compressor than MPEG-2 and can be up to 50% smaller in file size at a given quality. Digital satellite TV is moving towards MPEG-4 instead of MPEG-2.
NTSC
National Television Standards Committee. The analog TV standard used over the past 50 years in the U.S.A. Analog TVs and VCRs have NTSC tuners built in and will not be able to receive broadcast TV signals after Feb. 2009 without using a DTV converter box. The NTSC established the first color TV standard in 1953 and is the North American standard for video and broadcasting. Also used in the Caribbean, South Korea, Japan and South America. A 30 fps signal with 525 lines of resolution of which 480 are viewable. Transmitted via a 6MHz channel.
Pixel
Short for picture element, a single displayable video dot.
Pixelization
There are two types of pixelization. The creative type that is purposely used to obscure license plates and peoples faces to hide identity, and the type that is a TV signal problem. When you see pixelization , the signal is at the point where it has come through entirely but there is a delay in processing the information. In other words, the signal and video processing of your equipment can't keep up with one another. If the problem persists, eventually you'll see a blank screen. Satellite TV and cable subscribers experience this in adverse weather conditions when the wind or rain is interfering with the signal and it can't get through entirely. First it will pixelize, then black out all together. Broadcast TV signals which are too weak for the reception method you are using can cause pixelation. You may need a better/bigger antenna to acquire the TV signals appropriately so pixelation does not occur.
Progressive scan
A progressive scan format, such as 720p, will draw all the horizontal lines in the picture in one frame. This leads to a crisper image.
QAM
Quadrature Amplitude Modulation. The modulation technique used by cable TV providers to send TV signals over cable networks. A type of digital modulation technique used to carry signals in digital cable and cable modems which usually has a number before it denoting its bit density such as 64-QAM. Cable?s equivalent to 8VSB. A QAM tuner will allow you to see digital cable channels without a cable box but only those that are sent without restriction (not scrambled). Digital satellite TV uses its own modulation technique called QPSK (Quadrature Phase Shift Keying).
Resolution
The density of lines and dots per line which make up a visual image. Usually, the higher the numbers, the sharper and more detailed the picture will be. In terms of DTV, maximum resolution refers to the number of horizontal scanning lines multiplied by the total number of pixels per line, called pixel density.
Response Time
This is listed in milliseconds and describes the amount of time it takes to turn a pixel from off to on and back to off again. While a CRT Tube TV "repaints" the picture on the entire screen, LCD's work differently. Unlike a TV tube, LCD's are digital in nature and pixel based. The "response time" pertains to the time it takes for an LCD to make a pixel go from active (black) to inactive (white) and back to active (black) again. It is measured in milliseconds (ms). The faster the response time, the better.
Failure to switch efficiently can cause smearing, ghosting or trailers where the image of a previously displayed image is still on the screen after a new image is displayed. This can happen with fast moving objects such as following a baseball pitch. LCD's are getting progressively better at this, while 8 to 12ms is more common, response times have gotten as fast as 6ms with some HDTV LCD's now as fast as 4ms.
Refresh Rate
The refresh rate is the number of times a display's image is repainted or refreshed per second. The refresh rate is expressed in "Hertz." A refresh rate of 75 means the image is refreshed or "redrawn" 75 times in one second. Acceptable refresh rates for the human eye is anything over 70hz. Refresh rates pertain mostly to Plasma and CRT Tube tv's. Low refresh rates result in on-screen flicker, which can make the eye tired as the screen isn't refreshing fast enough for the human eye.
SDTV
Standard Definition TeleVision. A class of digital television (DTV) that refers to the 480i format. 480i is an interlaced video format that produces a full frame of 480 lines of video in two successive fields. The first field includes the odd lines and the second field includes the even lines. Sometimes used to refer to regular analog television.
STB (Set-Top-Box)
Any external box that incorporates a digital tuner and/or converter/de-scrambler. May contain a recorder.
UHF
Ultra High Frequency. The 300MHz to 3GHz band of radio frequencies used for broadcast television among other things including Wi-Fi.
VGA (Video Graphics Array)
An early computer standard that has a resolution of 640 x 480.
XGA (Extended Graphics Array)
A computer standard referring to a display that can output a resolution of 1024 x 768.
WXGA
WXGA defines a class of XGA displays with a width resolution sufficient to create an aspect ratio of 16:9. Resolution is defined by the number of pixels that a display uses to create an image. A WXGA display has 1366 to 1280 pixels horizontally and 768 to 720 pixels vertically.
|
|
|
