What is HDTV?

HDTV stands for High-Definition Television. HDTV is the new standard of television viewing. The hallmark of HDTV is the rectangular “Wide” screen and the high resolution of display. From the consumer’s perspective, HDTV translates to better visual and acoustic enjoyment to TV viewing. HDTV is an upgrade of digital technology from analog technology.

HDTV is a digitally delivered signal whereas Standard Definition Television (SDTV) had historically been delivered as an analog signal; however it is now being delivered digitally in many cable and satellite systems. An HDTV signal provides six times the number of pixels than an SDTV signal, resulting in a much sharper image on the display.

There is a class of digital television that is getting a lot of press right now. It is called High-Definition Television, or HDTV. HDTV is high-resolution Digital television (DTV) combined with Dolby Digital surround sound (AC-3). HDTV is the highest DTV resolution in the new set of standards. This combination creates a stunning image with stunning sound. HDTV requires new production and transmission equipment at the HDTV stations as well as new equipment for reception by the consumer. The higher resolution picture is the main selling point for HDTV. Imagine 720 or 1080 lines of resolution compared to the 525 lines you are used to in the U.S. (or the 625 lines in Europe) -- it's a huge difference!

Benefits of High Definition Picture and Sound

Much like the advent of color TV, High Definition dellivers an enhanced viewing experience. High- Definition offers Digital superiority, amazing detail, digital surround sound audio, better quality DVD playback and so on. It's no wonder why HDTV is one of the hottest selling electronics in the country. Once you experience it, you'll get it. A few details behind the power of HD:

The Shape's the Thing: Aspect Ratio

Aside from dramatically improved picture quality and multi-channel digital sound, the most noticeable difference between HDTV and other TVs is the shape of the viewing area which is defined by the aspect ratio.

The almost square aspect ratio that has been used so extensively for decades is 4:3 -- the screen is 4 units wide for every 3 units high. By comparison, the HDTV specifications call for the aspect ratio for high-definition viewing to be 16:9, much like a movie theater screen.

Why HDTV Looks So Crisp and Sharp

Understanding what resolution means to picture quality will make you a more savvy high-definition buyer. In television terms, resolution refers to the clarity of the screen image based on the number of pixels on the screen. HDTV is the clear winner on resolution. For example, the image on an older 4:3 aspect ratio screen typically is divided into 480 lines, each with 720 pixels. An HDTV with 1080 lines with 1920 pixels in each line has six times the pixel density.

The image on the screen can be created using two different scanning methods: interlaced and progressive. The "p" or the "i" you see in terminology such as 720p or 1080i refers to the type of scanning used (progressive or interlaced) and the numbers identify how many viewable on-screen lines the TV offers. As the number gets larger, the screen has more lines and more pixels to deliver a sharper, more vivid image.

Interlaced Scanning

On most TV screens anyone has watched for the last 50-60 years, the image is created using interlaced scanning. The lines on the screen are divided into two sections called fields -- one field includes the even numbered lines, the other the odd lines. So, each field (the even and the odd) contains half of the image to be displayed.

In rapid succession, all of the odd numbered lines of the picture are painted onto the screen in about one sixtieth of a second, followed by the display of the even numbered lines in the next sixtieth of a second. Each new image is displayed so quickly that your eye is unaware of the process that's creating the video image.

Progressive Scanning

Instead of combining two fields to display a complete image, progressive scanning treats all the lines as one field and displays them in one sixtieth of a second. This speedy delivery of the entire image on the screen gives a more consistent-looking, clearer picture.

HDTV - A Closer Look at What Makes HDTV Different

The usual National Television Standards Committee (NTSC) analog TV screen in the U.S. has 525 scan lines, with 480 actually visible. The usual TV has an effective picture resolution of about 210,000 pixels. In the highest resolution digital TV formats, each picture contains about two million pixels. This means about ten times more picture detail on the HDTV screen! On an analog TV the lower resolution is not as noticeable because typically the screen image is constantly changing.

HDTV is part of several standards incorporated in digital television or DTV. Basically, DTV is composed of three separate standards:

• HDTV 1080 (1080 lines of resolution, 16:9 aspect ratio)
• HDTV 720 (720 lines of resolution, 16:9 aspect ratio)
• SDTV (480 lines of resolution, 16:9 or 4:3 aspect ratio)

Of the eighteen DTV formats, six are HDTV formats—five of which are based on progressive scanning and one using interlaced scanning. Of the remaining formats, eight are SDTV (four wide-screen formats with 16:9 aspect ratios, and four conventional formats with 4:3 aspect ratios), and the remaining four are Video Graphics Array (VGA) formats. Stations are free to choose which formats to broadcast.

Formats used in HDTV:

• 720p - 1280x720 pixels progressive
• 1080i - 1920x1080 pixels interlaced
• 1080p* - 1920×1080 pixels progressive

Interlaced or Progressive refers to the scanning system. In an interlaced format, the screen shows every odd line at one scan of the screen, and then follows that up with the even lines in a second scan. Since there are 30 frames shown per second, the screen shows one half of the frame every 1/60 of a second. For smaller screens this is less noticeable. As screens get large the problem with interlacing is flicker. Progressive scanning shows the whole picture, every line in one showing, every 1/60 of a second. This provides for a much smoother picture, but uses slightly more bandwidth.

1080p is currently the digital standard for filming digital motion pictures.

MPEG-2

Broadcasters are having to squeeze the increased picture detail and higher quality surround sound into the same 6-megahertz bandwidth used by analog television. Compression software, very similar to what is used in personal computing, allows this to happen.

Digital TV relies on a compression and encoding scheme known as MPEG-2 to fit its stunning images into a reasonable amount of bandwidth. In each image, the MPEG-2 software records just enough of the picture without making it look like something is missing. In subsequent frames the software only records changes to the image and leaves the rest of the image as-is from the previous frame. MPEG-2 reduces the amount of data by about 55 to 1. MPEG-2 already is the industry standard for DVD videos and some of the satellite TV broadcast systems. Compression reduces image quality from what is seen by the digital camera at the studio. However, MPEG-2 is very good at throwing away image detail that the human eye ignores anyway. The quality of the image is very good, and significantly better than traditional analog TV.

The use of MPEG-2 permits a HDTV receiver to interact with computer multimedia applications directly. For example, a HDTV show could be recorded on a multimedia computer, and CD-ROM applications could be played on HDTV systems. A Digital TV decodes the MPEG-2 signal and displays it just as a computer monitor does, giving it high resolution and stability.

What Does DVI Mean? What is HDCP? What is HDMI? DVI stands for digital visual interface. DVI is an all-digital link between a video/audio source such as an HDTV set-top and a display device such as an HDTV. The DVI link provides an uncompressed digital stream at rates up to 5 Gbps between the two devices. The DVI link does not contain audio, and as such, audio still need to be connected from the set-top to the HDTV or home theatre system. One advantage of DVI is that the link allows graphics to be sent along the link as well. This allows the user interface from the set-top to be displayed on the HDTV. The DVI 1.0 connector and cable on the set-top and HDTV looks as follows:

HDCP stands for High-Bandwidth Digital Content Protection. HDCP is the copy protection standard that is tied to DVI. HDMI is the next generation of DVI. HDMI stands for High-Definition Multimedia Interface. The main difference between HDMI and DVI 1.0 is that HDMI adds audio to the DVI link and is a smaller connector. The HDMI interface will be backwards compatible to the DVI 1.0 interface, meaning that you can connect up a set-top to an HDTV, where one has DVI 1.0 and the other has HDMI. HDMI in HDTVs has been available since 2004.

The Ultimate Home Theater Experience

HD delivers wide-screen, crystal-clear pictures, CD-quality Dolby Digital surround sound. Awaken your senses with vivid colors, lifelike picture quality, and amazing sound.

So, what do you need to view HD programming?  It's simple.

• High-Definition TV capable of receiving and displaying high-definition programming.
• HD Digital Set-top Terminal from Mid-Hudson Cable.
• HBO and/or Cinemax to receive HBO HD and Cinemax HD.

The Digital Cable package from Mid-Hudson Cable is the starting point for enjoying HD programming. An HD cable receiver will deliver both standard digital and HD programs from one device. Your costs will include the price of the digital cable package and some HD channels which come standard with Digital Cable. There is no purchase of additional equipment necessary, and cable does not require a one or two year service agreement for digital or HD service. If you subscribe to Premium channels such as HBO or Cinemax, you will receive HBO HD and Cinemax HD.  And with Mid-Hudson Cable HD, you never have to purchase extra equipment like dishes or antennas - you can enjoy all the HD programs you love directly via our advanced fiber optic network. Plus, with our HD DVR, you can record your favorite HDTV shows, and then watch them in HD anytime you want!

Mid-Hudson Cable is making a commitment to ad HD programming and will continue to add new channels as soon as they become available.  

Click here for details on HD programming available.

Before you buy anything you need to make three choices:

• What will be the source of your HD programming?
• Do you want an HDTV-Capable monitor or HDTV-Ready Television?
• What type of display technology is best for your viewing habits and your home?

Selecting the source for your HD programming will directly impact whether you go with an HD-capable monitor or a HD-ready television. There are multiple things to take into consideration before you select the display technology that's most affordable and best suited for your home.

First, you need some background information to help you make the best HDTV choice.

HDTV-Ready or HDTV-Capable?

As you scan the advertisements in the newspaper from your local consumer electronics retailers, you may notice a variance of $300-$500 for HD products with the same sized screens. Some of that may be attributable to the display technology the units use but more likely it is the result of what an HDTV-ready television includes that is not available from an HDTV-capable monitor.

HDTV-Ready Television

• Aspect ratio of 16:9 or 4:3 with scanning rates supported of 720p and 1080i, or higher.
• Requires an external HDTV tuner (i.e., HD cable box) to receive HD programs. For off-air broadcasts, requires an HDTV receiver and antenna.
• To hear Dolby audio, you will need a dedicated audio system connected to whichever HDTV receiver you use.

HDTV-Capable Monitor

• Aspect ratio of 16:9 or 4:3 with scanning rates supported of 720p and 1080i, or higher.
• Built-in HDTV tuner is ready for off-air HD signals from a special antenna. To view HDTV programming, a cable box is required.
• To hear Dolby audio, you will need a dedicated audio system connected to the HDTV-ready television for off-air audio or to the HD cable box for audio.

CableCARD Devices and Digital Cable-Ready Televisions:

Another Option

As you shop for an HDTV, you may see some digital cable-ready televisions (DTV) that can receive digital cable service (including HD programming) using a small plug-in card instead of a cable box. The CableCARD devices look much like PCMCIA cards used to add modems or memory to laptops. Before you decide to purchase a TV with CableCARD capability, contact Mid-Hudson Cable to be sure we can provide you with the necessary CableCARD that works with yourTV.  Currently Mid-Hudson Cable CableCARDs are not in operation.   Please note that current versions of these cards do not support two-way, on-demand cable service or an Electronic Programming Guide (EPG). You’ll have to use a telephone connection to receive downloaded EPG information. Development is underway to provide cards that support two-way services.

Use this matrix to help match your HD programming source with the best display.

HDTV-Capable Monitor

HDTV-Ready Television

 Which Type of Display?

HDTVs are available in several types of displays, each with its advantages and disadvantages. Depending on the method used for displaying the on-screen image, you may notice differences in picture brightness or clarity based on the viewing angle or for other reasons. Be sure you have a location in your home that is big enough to accommodate the HDTV. Some of the projection models may require a fair amount of floor space. You don’t want to end up putting nose prints on your HDTV because you’re sitting three feet from the screen in a room that is undersized for the set you buy. Also, be aware of where the windows are in the room where you’ll use your new HDTV. The room’s brightness can have an impact on the display type you choose. These are the primary display technologies you’ll see in stores today:

Direct View CRT (Cathode Ray Tube)

This is the familiar TV tube found in most “regular” television sets. It is one of the lower-cost technologies available for displaying today’s HDTV programs. However, because of the weight of the glass tube, these HD television sets are limited to a maximum size of 32 to 40 inches.

Rear Projection TV

This is another type of CRT system. In rear projection televisions, the image is projected onto a mirror or series of mirrors that reflect the image onto the screen at the front of the set. Rear projection technology is often the least expensive way to get a larger screen compared with a regular CRT. However, rear projection sets get deeper as screen size increases, so large screen models require a lot of space. Viewing angle may affect the perceived clarity of the on-screen image.

Front Projection TV

This system has an image source that projects the HDTV signals onto a screen pretty much the same way a projector does in a movie theater. The only factors that limit size in these systems are the amount of light the system outputs, the distance from the projector to the screen and the size of the screen onto which the HDTV images are to be projected.

DLP (Digital Light Processing)

This projection display technology is more expensive than CRT projection systems, but not as costly as LCD or plasma screens. Using a digital micromirror device, DLP images are produced by hundreds of thousands of microscopic mirrors, one for each pixel on the screen. This results in razor sharp picture quality and the ability to display very subtle color changes to support over 16 million hues on the HDTV screen. The DLP light engine delivers a bright picture to the screen making this display a good choice for use in a bright room. Pixels are tightly packed to deliver good color and resolution. DLP is popular choice for a projection display that combines value with performance.

LCD (Liquid Crystal Display) (This technology has been used for some time in laptop computer screens.)

LCDs are flat screens/panels filled with liquid. Each pixel on the screen is lighted individually to produce a display. One strength of LCDs is the picture quality is very consistent even when you are not viewing images directly in front of the display.

LCoS (Liquid Crystal on Silicon)

LCoS is the next step in LCD technology and offers remarkable resolution because several million pixels are etched into each of the silicon chips that make up the display. This superior, concentrated pixel count delivers a great image and enables LCoS displays to be manufactured in much smaller versions for use in portable devices.

Plasma Displays

Some larger flat screens/panels use a conductive plasma instead of liquid crystal. These are commonly called plasma displays. Plasma displays are very sleek and thin, making them a hot choice among consumers who say this technology delivers the best color saturation, accuracy and vibrancy.

Screen Size - How Big is “Too Big?”

For optimum viewing you need to match the size of the screen with the dimensions of the room it will occupy and the distance you will need to sit from it. For HD screens, one manufacturer recommends a “rule of three” for how far to sit from a screen for the best view. Multiply the height of the 16:9 HD screen by three for the best viewing distance. Surprisingly, with HDTVs, you’ll discover that you actually need to sit closer than you think for the best view.

Use these general guidelines for 16:9 aspect ratio screens:

Use a combination of these optimum viewing distances, the type of HD display you have decided upon and the size of the room you plan to use as helpful guidelines for selecting an HD display that is best suited for your home.

More Screen Considerations

Another factor in your decision on display technology is the way you will be using your television set. If you play a lot of video games or spend a lot of time watching channels where text and graphics stay in the same location on the screen for quite a long time, you may want to choose an LCD, DLP or LCoS display. Static images may be “burned in” on plasma and CRT-driven rear-projection screens, leaving a faint, but permanent impression of the image on the screen. Many manufacturers have developed technology to overcome this problem so be sure to ask before you buy to see if this has been addressed in the model you select.

A Few Words About HDTV Connectors

You’ll need to become familiar with the three most common inputs for HDTV that you will come across in your search for the display best suited to fit your needs.

These HDTV connectors maximize your viewing experience:

 
Using a three plug video connector, component video delivers the best viewing experience by supporting superior color details, improved color purity, and a reduction in the impact that interference or other poor signal quality issues may have.

Digital Visual Interface (DVI)

DVI connectors transfer video signals in pure digital form, which is especially beneficial if you're using a plasma, LCD, or DLP TV. Signals are encrypted with HDCP (High-bandwidth Digital Content Protection) to prevent recording. There are two types of DVI connectors: DVI-D carries digital-only signals and DVI-I passes both digital and analog video signals. Some TVs feature DVI-I inputs for greater hookup flexibility.

High-Definition Multimedia Interface (HDMI)

An HDMI connector supports an all-digital link between an HD cable box and HDTV that combines digital video and digital audio on one connection rather than using separate connectors for each function. This delivers extremely high-quality digital video and audio. HDMI is fully backwards compatible with DVI.

Wrapping It All Up

How will you receive HD service?

Broadcast-only HD will limit you to whatever programs the networks choose to transmit over the air in HD. Cable service will deliver the networks’ broadcast HD programs, plus any cable HD programming available.

Do you want an HDTV-capable monitor with its built-in HD receiver or an HDTV-ready television and an HD cable box?

The HDTV-capable monitor will probably cost more than the HDTV-ready television. If your HD service is going to come via cable, you’ll still need the HD cable box to get HD programming on your HDTV. So, you may be able to save some money by buying an HDTV-ready television and accessing HD programming via an HD cable hookup.

Does the HDTV-capable monitor or the HDTV-ready television support 720p or 1080i (or higher) scanning?

Both scan rates support HD programming. Your TV must support one or the other.

How do I choose the right screen/display for HDTV?

Shop around a lot. Do some research at the HDTV manufacturers’ Websites BEFORE you go into the stores. Seeing the unit in action is probably the best way to make your choice. Stand in front of the unit and note the picture clarity. Then, walk to the left and right to see if the image clarity changes. Your budget will also play a big role in the product you buy.

You’re Ready for the Final Step

Now that this overview has taken much of the mystery out of HDTV, you’re ready to make your choices. Think about how much more you know now about HDTV than you did before you read the preceding information. Because you’re better informed, the jargon of HDTV will make more sense when you visit a consumer electronics store. And, most of all, remember that you’re in charge when it comes time to make your final choice. Weigh all the factors and rely on what you know. Then, sit back, relax, and get ready for the thrill of the most realistic, enjoyable video and audio home entertainment experience you’ve ever had.

Glossary of High Def Terms

480p means that the resolution of the picture is 852 vertical pixels by 480 horizontal pixels and p stands for progressive scanning. Although 480p is in the wide-screen format, it is not considered a high definition format. It is related to EDTV and current DVD's.

720p means that the resolution of the picture is 1,280 vertical pixels by 720 horizontal pixels and p stands for progressive scanning. Progressive scanning offers a smoother picture as 720 horizontal lines are scanned progressively or in succession in a vertical frame that is repeated 30 times a second.

1080i means that the resolution of the picture is 1920 vertical pixels by 1080 horizontal pixels and i stands for interlaced scanning. Interlaced scanning is based on the principle that the screen shows every odd line at one scan of the screen and then all the even lines in a second scan.

AC-3 The 5.1-channel sound system specified in the Standard for Digital-HDTV. Also known as "Dolby Digital," AC-3 delivers CD-quality digital audio and provides five full-bandwidth channels for front left, front right, center, surround left and surround right speakers, plus an LFE (low-frequency effect) subwoofer, for a total of 5.1 channels.

A/D Analog to digital conversion. Used at transmission end of broadcast.

Advanced Television Systems Committee (ATSC)

Advanced Television Systems Committee is responsible for establishing and developing digital television standards, as well as all 18 formats of Digital TV.

Addressable Resolution The highest resolution signal that a TV or monitor can accept. It is important to note that while a particular device (Digital-HDTV) is able to receive the resolution, it may not be capable of displaying it.

Analog TV Analog technology has been in use for the past 50 years to transmit conventional TV signals to consumers. "Standard" television broadcasts in analog TV. Analog signals vary continuously, creating fluctuations in color and brightness.

Anamorphic video Video images that have been "squeezed" to fit a video frame when stored on DVD. These images must be expanded (un-squeezed) by the display device. An increasing number of TVs employ either a screen with 16:9 aspect ratio, or some type of "enhanced-for-widescreen" viewing mode, so that anamorphic and other widescreen material can be viewed in its proper proportions. When anamorphic video is displayed on a typical TV with 4:3 screen size, the images will appear unnaturally tall and narrow.

Artifacts Artifacts are defined as unwanted visible effects in the picture caused by disturbances and errors in the video transmission or digital processing. Artifacts include “edge crawl” or “dot crawl” or “hanging dots” in analog pictures, and “pixelation”, “contouring” or “blockiness” in digital pictures.

Aspect ratio is ratio of width to height of a TV screen. It may be either traditional squarish 4:3 ratio of the National Television Systems Committee (NTSC) TV screen or 16:9 ratio of widescreen DTV formats for all HDTV (High Definition) and some SDTV (Standard Definition).

ATSC An acronym for Advanced Television Systems Committee, which is responsible for developing and establishing Digital-HDTV Standards; and the name of the DTV system used by broadcasters in the U.S.

Bandwidth, in general, means amount of information that can be carried in a given time period (usually a second). More exactly, it is a range of frequencies used for transmitting picture and sound information from transmitter to your TV. Federal Communications Commission (FCC) has allocated 6 MHz for TV broadcasters for each channel.

Barn Doors A term used in television production to describe the effect that occurs when a 4:3 image is viewed on a 16:9 screen. When this happens, viewers see black bars on the sides of the screen or "barn doors."

Bit rate is measured as "bits per second" (bps) and refers to the rate at which the data is transmitted. For Digital TV, the maximum possible bit rate within the bandwidth is 19.4 Mbps while SDTV has a lower bit rate. The higher the bit rate, the more data is processed which usually results to higher picture resolution or better sound quality.

Burn-in is the result of a static image or pattern appearing so regularly on a screen that it ages the phosphors and remains as a ghost image.

Codec is a short term for “Coder-decoder.” This device is used to convert analog video and audio signals into digital format, and vice verse, it can also convert received digital signals into an analog format.

Component Video Connection The output of a video device (such as a DTV set-top box), or the input of a DTV receiver or monitor consisting of three primary color signals: red, green, and blue that together convey all necessary picture information. With current consumer video products, the three component signals have been translated into luminance (Y) and two color difference signals (PP, PR), each on a separate wire.

Composite Video An analog, encoded video signal that includes vertical and horizontal synchronizing information. Since both luminance (brightness) and chrominance (color) signals are encoded together, only a single connection wire is needed. A composite video jack is usually a single RCA-type.

Compression allows the delivery of more programs in a single channel. It is an electronic manipulation of digital data that reduces and removes redundant and/or non-critical information in the digital picture and sound without noticeably degrading picture quality. One of the compression methods is called MPEG-2.

Computer Input Some HDTV sets have an input like SVGA or VGA that allows the TV sets to be connected to computers.

Contrast Ratio Measures the difference between the brightest whites and the darkest blacks a display can show. The higher the contrast ratio, the greater the ability of a display to show subtle color details and tolerate ambient room light. Contrast ratio is an important spec for all types of TV display, but especially for front projectors.

CRT (Cathode-Ray Tube) A CRT ("picture tube") is a specialized vacuum tube in which images are created when an electron beam scans back and forth across the back side of a phosphor-coated screen. Each time the beam makes a pass across the screen, it lights up a horizontal line of phosphor dots on the inside of the glass tube. By rapidly drawing hundreds of these lines from the top to the bottom of the screen, images are created.

D/A Conversion of digital to analog signals. The device is also referred to as DAC (D/A converter). In order for conventional television technology to display digitally transmitted TV data, the data must be decoded first and then converted back to an analog signal.

Datacasting Also known as "enhanced TV." Datacasting is the act of providing enhanced options offered with some digital programming to provide additional program material or non-program related resources. This allows viewers the ability to download data (video, audio, text, graphics, maps, services, etc.) to specially equipped computers, cache boxes, set-top boxes, or DTV receivers.

Decoder See "codec." A device or program that translates encoded data into its original format (i.e., it decodes the data.)

Deinterlacing The process of converting an interlaced-scan video signal (where each frame is split into two sequential fields) to a progressive-scan signal (where each frame remains whole). De-interlacers are found in digital TVs and progressive-scan DVD players. More advanced de-interlacers include a feature called 3-2 pulldown processing. For TVs, de-interlacing is often referred to as "line-doubling" or "upconversion."

Digital Digital refers to the circuitry in which data-carrying signals are restricted to one of two voltage levels, corresponding to logic 1 or 0.

Digital Cable A service provided by many cable providers, digital cable offers viewers more channels. Contrary to many consumers' beliefs, digital cable is not the same as High-Definition Television or digital television; rather digital cable simply offers cable subscribers the options of paying for more services. Digital Monitor: DTV monitors are televisions that can display a digital signal but lack an integrated tuner (unlike an integrated digital set), and thus cannot receive a digital broadcast signal without an additional set-top box.

Digital Television (DTV) Digital TV is the umbrella term encompassing High-definition Television and several other applications, including Standard Definition Television, datacasting, multicasting and interactivity.

Digital Tuner A digital tuner serves as the decoder required to receive and display digital broadcasts. It can be included inside TV sets or via a set-top box.

Direct-view TV The conventional and most common type of TV, which uses a single large (up to 40") CRT to display images.

DLP (digital light processor) A proprietary electro-mechanical device invented by Texas Instruments that reflects light on a pixel-by-pixel basis to create a projected image. The key components of a DLP are the digital micromirror device, which actually stores image information and reflects light with thousands of 16x16-micron mirrors based on that information, a scan converter that decodes multiple signal sources into progressive red, green and blue information and an RGB color filter wheel.

Dolby Digital (Dolby AC-3) Dolby Digital, also called Digital 5.1 or AC-3, is a five-channel surround sound system which delivers CD-quality digital audio and provides five channels of full frequency for front left, front right, center, surround left and surround right speakers, plus one channel for LFE (low frequency effect) subwoofer. It is the official audio standard for Digital TV and HDTV.

Downconvert A term used to describe the format conversion from a higher resolution input signal number to a lower display number, such as 1080i input to 480i display. Some HDTV tuners are able to downconvert digital HDTV signals for display on a regular analog TV.

DTS Digital Theater Systems sound. Discrete 5.1 channel surround system similar but not the same as Dolby Digital. Dolby Digital is the DTV standard, but DTS competes with it on DVD and in the movie theaters.

DTV (Digital Television) DTV stands for Digital Television. It refers to all digital television formats and standards established by the Advanced Television Systems Committee (ATSC). Two basic DTV standards are HDTV (high-definition television) and SDTV (standard-definition television)

DVI (Digital Visual Interface) DVI is a standard that provides a high-bandwidth, low-cost digital interface between a video source and a display device. It is capable of carrying uncompressed unprotected high resolution video transfers of HDTV signals, and supports real-time complex graphics displays and user interfaces found in program guides andother interactive features for high definition television.

DVI w/HDCP (Digital Visual Interface with High Density Copy Protection) This is the same as above adding high-density digital copy protection, primarily for the secure transfer of high-resolution video content.

EDTV (Enhanced-Definition Television) EDTV stands for Enhanced Definition Television. The picture quality of EDTV is superior to that of standard analog TV (480i) but not as good as HDTV (1080i or 720p). EDTV displays the picture at a resolution of 852x480 (480p) lines in either 4:3 or 16:9 aspect ratios and it includes Dolby Digital sound system.

EPG EPG stands for electronic program guide. It is a system displaying channels and program data on-screen for an extended time period (typically 36 hours or more).

Frequency The number of times per second that a signal fluctuates. The international unit for frequency is the hertz (Hz). One thousand hertz equals 1 KHz (kilohertz). One million hertz equals 1 MHz (megahertz). One billion hertz equals 1 GHz (gigahertz). Television is broadcast in frequencies ranging from 54 MHz to 216 MHz (VHF) and 470 MHz to 806 MHz (UHF).

Flat-panel TV Flat-panel TV typically displays picture using gas plasma or LCD technology and is only a few inches thick.

Frame rate The rate at which frames are displayed. The frame rate for movies is 24 frames per second (24 fps). In regular NTSC video, the frame rate is 30 fps. The frame rate of a progressive-scan format is twice that of an interlaced-scan format it's at 60 fps.

Front-projection TV Front-projection TV comprises 2 parts – a separate front projector (usually placed on a table or ceiling-mounted) and a reflective screen (or simply a wall). The projector is placed at one end of the room, the screen is at the other end, and the speakers may be placed wherever they will provide you good sound experience. The picture can be rather large but remember – the larger the picture, the more visible the pixels or scan lines and the darker the image.

Gain Measures the light-reflecting ability of a projection screen. The higher the number, the greater the amount of light reflected back to the viewer(s).

Generation Loss This refers to video degradation caused by successive recordings (dubs of other dubs) from the master source. This is overcome by digital recording.

Ghosting Ghosting means multiple overlaid TV images or “ghosts” which you can notice around the objects while watching TV. Ghosting is caused by the broadcast signal traveling to your TV through various obstacles, for example hills or tall buildings, and your antenna picks up the original TV signal along with signals reflected by the obstacles. If the ghosting is changing rather than static, it may be caused by the signal reflected by flexible objects, for example trees.

Grayscale This describes the ability of a display to be in a state between full ON and full OFF. Each of these definable states is a “gray level”. The grayscale is composed of the number of gray levels. The more levels a display has the better.

HDCP (High-Bandwidth Digital Content Protection) HDCP encryption is used with high-resolution signals over DVI and HDMI connections and on D-Theater D-VHS recordings to prevent unauthorized duplication of copyrighted material.

HDMI (High Definition MultiMedia Interface) HDMI assures that the best video signal is always sent from source (e.g., HDTV signal) to the display (e.g., plasma television). It does this by allowing uncompressed video and multi-channel audio data to be input to the display device through one single cable. The need for multiple analog connections for high-resolution audio and video are eliminated. Without a HDMI connection one would need 3 video connections for high definition video and 6 audio connections for high-resolution audio.

HD-ready Describes a television that is capable of displaying one or both of the prescribed high-definition television formats (720p, 1080i) but is not equipped with the requisite tuner/converter to receive digital signals.

HDTV (High-Definition Television) HDTV stands for High Definition Television. HDTV refers to the highest-resolution formats of the 18 total DTV formats. With twice the vertical and horizontal picture resolution, the picture of HDTV is approximately twice as sharp as that of NTSC. HDTV has widescreen aspect ratio of 16:9 and Dolby Digital sound system. Currently used HDTV formats - 1080i and 720p both offer reduced motion artifacts like ghosting and dot crawl.

High Def Usually refers to the High Def Forum but can also refer to High Defintion (see below).

High Definition Usually refers to a video format consisting of either 720 active lines of progressive video or 1080 active lines of either progressive or interlaced video.

IEEE-1394 (also FireWire or i.LINK) High-speed digital video and data interface technology adopted by the Institute of Electrical and Electronics Engineers; a nascent standard for connecting digital television and computers to various components and peripherals, such as Digital VHS, set-top HDTV tuner boxes and digital video camcorders.

Interactive Television This is when TV programming features interactive content and enhancements, blending traditional TV viewing with the interactivity of a personal computer.

Interlaced Scanning Interlaced scanning is a method based on the principle that the screen shows every odd line at one scan of the screen and then all the even lines in a second scan. There are 30 frames shown per one second and this can make larger screen flicker, which is the usual problem with interlacing. However, LCD and plasma screens cannot display interlaced signals and must first convert them to a progressive format and then they can display the transmitted images.

LCD (Liquid Crystal Display) LCD stands for Liquid Crystal Displays. LCD technology is one of the methods used to create flat-panel TVs. The display consists of two polarizing transparent panels and a liquid crystal solution sandwiched in between. An electric current passed through the liquid causes the crystals to align so that light cannot pass through them. Each crystal acts like a shutter, either allowing light to pass through or blocking the light. The pattern of transparent and dark crystals forms the image.

LCoS (liquid crystal on silicon) A type of LCD and projection TV display technology (can be used in rear-projection and front-projection TVs), LCoS sandwiches liquid crystals between a plate of glass and a silicon microchip rather than between two layers of glass.

Letterbox Letterbox refers to the image of a wide-screen picture on a standard 4:3 aspect ratio television screen, typically with black bars above and below. It is used to maintain the original aspect ratio of the original source (usually a theatrical motion picture of 16:9 aspect ratio or wider).

Light output Is the amount of light produced by a front projector. Expressed in "lumens" or "ANSI lumens," with the higher number indicating greater light output.

Lumen The unit of measure for light output of a projector.

Luminance The brightness or black-and-white component of a color video signal. Determines the level of picture detail.

Multicasting The option to multicast was made possible by digital technology to allow each digital broadcast station to split its bit stream into 2, 3, 4 or more individual channels of programming and/or data services. (For example, on channel 7, you could watch 7-1, 7-2, 7-3 or 7-4.)

Native Resolution Native resolution is the actual number of plasma cells that can be illuminated at once, and it's the very first thing you should check when shopping for a plasma display. In order to enjoy high-definition programming, your TV must have a minimum native resolution of 720p. (Pioneer PureVision plasmas actually exceed high-definition standards with 768p native resolution.)

NTSC (National Television Systems Committee) NTSC or National Television System Committee is the organization that develops technical standards for black-and-white television and color television. NTSC established the 525-line (480 visible) analog broadcast TV standard. The new DTV digital broadcast standard will eventually replace NTSC.

Over-the-air Broadcast (OTA) Over-the-air Broadcast is also called Terrestrial Broadcast. It is standard over-the-air broadcast to an antenna, as opposed to satellite or cable transmission.

Picture-in-picture (PIP) Picture-in-picture is a television feature in which you can see one program inside a small window on the screen, while watching another program on the large background screen. You can choose whatever you wish – you can watch two TV programs simultaneously or you can watch TV and video or DVD at the same time.

Pixel Short for "picture element" The smallest bit of data in a video image. The smaller the size of the pixels in an image, the greater the resolution.

Plasma Displays (PDP) Plasma display is created by thousands of tiny tubes filled by ionized gas in a plasma state.

Progressive Scanning Progressive scanning is used by some HDTVs. Progressive scanning offers rather smooth picture as 720 or 1080 horizontal lines are scanned progressively or in succession in a vertical frame that is repeated 30 times a second. Some displays, for example LCD and plasma use progressive scanning method, while CRTs may use progressive (e.g. in computer monitors) or interlaced scanning method.

Rear Projection Rear projection is a TV system where the picture is projected against a mirror inside the cabinet and you can watch it as you would an average television. Until recently, the rear projection TVs comprised three CRTs but the new types of rear projection TVs include LCD.

Refresh Rate The refresh rate for a monitor is measured in hertz (Hz) and is also called the vertical frequency, vertical scan rate, frame rate or vertical refresh rate. The old standard for monitor refresh rates was 60Hz, but a new standard developed by VESA sets the refresh rate at 75Hz for monitors displaying resolutions of 640x480 or greater. This means that the monitor redraws the display 75 times per second. The faster the refresh rate, the less the monitor flickers.

Resolution Resolution reflects the density of lines, and dots per line which make up a visual image. It is measured by the number of pixels displayed. The level of resolution directly affects picture quality. Usually the higher number of lines and dots means also sharper and more detailed picture. Analog TV has a little over 200,000 color pixels while HDTV, with 1080 vertical pixels and 1920 horizontal ones, has more than 2 million pixels creating the image.

Sampling This is the digital process by which analog information is measured, often millions of times per second, in order to convert analog to digital.

SDTV (Standard-Definition Television) SDTV stands for Standard Definition Television. The SDTV picture, having either in 4:3 or 16:9 aspect ratios, is better and of higher quality than the one of NTSC, however, it does not reach the quality and resolution of HDTV. SDTV is based on 480 lines of vertical resolution and in both interlaced and progressively scanned formats.

Set-top Box (STB) Also called converter boxes, these receivers convert broadcasts (either analog cable, digital cable, or HDTV) for display on a television. HDTV-ready TVs (those without a built-in HDTV tuner) must be connected to a compatible HDTV tuner set-top box in order to receive digital television programs.

SVGA This acronym is short for the "Super Video Graphics Array" display mode. SVGA resolution is 800 x 600 pixels.

S-Video Separated video. An encoded video signal which separates the brightness from color data. S-video can greatly improve the picture when connecting TVs to any high quality video source such as digital broadcast satellite (DBS) and DVDs.

UHF Ultra high frequency, the range used by TV channels 14 through 69.

Upconverting Process by which a standard definition picture is changed to a simulated high-definition picture.

VGA This acronym is short for the "Video Graphics Array" display mode. VGA resolution is 640 x 480 pixels.

VHF Very high frequency, the range used by TV channels 2 through 13.

Widescreen Widescreen TV is the television with 16:9 aspect ratio. 16:9 is the aspect ratio of movie screen and widescreen DTV formats used in all HDTV (High Definition TV) and some SDTV (Standard Definition TV); it stands for 16 units of width for every 9 units of height.