HDTV Glossary

High Definition Television (HDTV)

The generally agreed upon definition of HDTV is approximately twice the vertical and horizontal picture resolution of today's NTSC TV, which essentially makes the picture twice as sharp. HDTV also has a screen ratio of 16:9 as compared with most of today's TV screens, which have a screen ratio of 4:3. HDTV offers reduced motion artifacts (i.e. ghosting, dot crawl), and offers 5.1 independent channels of CD-quality stereo surround sound, (also referred to as AC-3).

NTSC

National Television Standards Committee responsible for developing Standards for "traditional" Analog TV, prior to Digital-HDTV.

Pixel

Pixel Term used for "picture element;" the smallest element in a television picture. The total number of pixels limits the detail that can be seen on a television. A typical television set has less than half a million pixels. The pixel count for HDTV is nearly two million.

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.

5.1 Surround Sound-

This is the current generation of multi-channel surround sound that includes 6 channels of sound, including 5 full frequency independant channels of discrete audio (front right&left, rear right&left, center)and one seperate .1 channel (20-20 000Hz) for Low Frequency Effects (LFE), which is directed at your subwoofer. With 5.1 surround, the rear surround speakers are now in stereo, versus mono for Dolby Pro-logic. This translates into a much more realistic sound quality. The two most common 5.1 surround formats include Dolby Digital, or AC-3 and DTS or Digital Theater Sound.

6.1 Surround Sound-

The next generation of digital surround sound is known as 6.1. This adds to the 5.1 experience by adding a new rear surround center channel, which works with the rear left and right surround channels to produce more realistic sound effects. In order to receive 6.1 surround sound, you need a 6.1 capable receiver (Dolby Digital EX/DTS ES) and also a 6.1 encoded source, such as a DVD. At the moment, very few sources are 6.1 encoded, so your 6.1 receiver will automatically fall back to 5.1 or pro-logic mode, depending on the source material.

Standard Definition Television (SDTV)

SDTV refers to DIGITAL transmissions with 480-line resolution, either interlaced or progressive scanned formats. SDTV offers significant improvement over today's conventional NTSC picture resolution, similar to comparing DVD quality to VHS, primarily because the digital transmission eliminates snow and ghosts, common with the current NTSC analog format. However, SDTV does not come close to HDTV in both visual and audio quality.

ASPECT RATIO

The ratio of screen width to screen height. Example: 16x9, 4x3.

Addressable Resolution

The highest resolution signal that a display device (TV or monitor) can accept. Caution: Consumers should be aware however, that although a particular device (Digital-HDTV) is able to receive the resolution, it may not be capable of displaying it.

ATV

"Advanced Television" is an earlier term used to describe the development and advance applications of digital television, now simply referred to as DTV.

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.

DBS

Abbreviation of "Digital Broadcast Satellite" - refers to digital TV transmissions via satllite. Digital Output-

A pure digital audio signal output that allows for a digital connection. The output comes in either a coaxial cable (RCA type)or a TOSLink optical cable. Digital outputs provide less noise and interference than any other type of connection.

Digital Light Processing (DLP)-

This is a line of projection televisions that provide premium quality picture quality without the use of a cathode ray tube. The projectors use a digital micro mirror device (DMD) to produce the images, which are then enlarged to fill the screen. The DMD device has more than 1.3 million tiny mirrors that are used to create the images in the same manner as pixels are used in cathode ray tube devices. DLP equipped televisions typically have a higher lumen and contrast ratios.

Dolby Digital-

A well recognized multi-channel perceptual coding scheme, introduced by Dolby Labs and initially known as AC-3(Audio Coder 3). Dolby Digital was introduced into movie theaters in June 1992 as Dolby Stereo Digital. Dolby's earlier coding scheme, known as Dolby Surround or Pro-Logic is a single band limited surround channel with a range between 100 and 700Hz. In comparison, Dolby Digital offers a full dynamic range on all five main channels of 3-20 000Hz. On Laser discs and DVD's, the Dolby Digital scheme is carried on the right analog FM track. The left analog FM track usually carries the mono version of the soundtrack. Perceptual coding has been developed to decode the digital audio and eliminating the data that we cannot hear. The Dolby Digital channels are discrete, unlike Pro-logic so they cannot interfere with one another or bleed to an adjacent channel. The Dolby Digital signal is fed into the audio receiver via digital coaxial or optical cables.

Dolby Digital EX-

This is the next generation of Dolby Digital surround sound and incorporates 6.1 discrete channels, adding in a new rear surround center channel. This extra rear surround channel works with the usual left and right surround channels to produce an intensified realism that is designed to draw you even further into the action. In order to receive the 6. channels, you will need a Dolby Digital EX receiver and also 6.1 source material, such as a 6.1 encoded DVD.

Dolby Pro-Logic-

The older Dolby Pro-logic coding scheme is a matrixed system in which the four channels of information(left,right,center,surround) are folded into two discrete channels so they can be encoded onto the source material such as a broadcast,VCR,DVD or laser disc. The Pro-logic processor then extracts the four channels of data from the two encoded channels and directs them to the speakers. The rear surround channel is divided over two speakers, however it is a mono signal. Pro-logic II is a variation of the original scheme which allows more power and presence to the surround field.

Digital Theater Sound (DTS)-

DTS is another popular digital 5.1 surround scheme developed by MCA/Universal and Steven Spielberg. Similar to Dolby Digital, the encoded DTS scheme is passed to the receiver via the digital coaxial or optical cables. It is designed to filter the audio signal into frequency bands which match the perceptual bands of human hearing.

Digital Theater Sound ES (DTS ES)-

DTS introduced the first next generation 6.1 surround sound scheme, adding in a new rear surround center channel to produce more stunning and realistic sound effects. In order to receive the 6. channels, you will need a Dolby Digital EX receiver and also 6.1 source material, such as a 6.1 encoded DVD.

Resolution-

Resolution refers to the number of lines that can be displayed on a standard television. Theoretically the more lines of resolution that can be displayed, the better the picture quality. The NTSC broadcast television standard is 525 lines, of which 330 lines are displayed on a standard television. VHS videotapes offer approximately 240 lines, super VHS tapes offer up to 400 lines, and DVDs offer approximately 500 lines of resolution.

Liquid Crystal Display (LCD)-

LCD front and rear projection televisions use LCD panels to create images, which are then enlarged to fill the screen. An LCD projector produces rich, vibrant colors and sharp contrast to produce a large, high quality picture.

Liquid Crystal on Silicon (LCOS)-

Liquid crystals are coated onto a silicon chip, which uses a reflective, aluminized layer. This reflective design increases contrast. Since it is a digital display device, LCOS also eliminates image burn in.

MPEG-2- MPEG-2

is the current data compression system widely in use today. It compresses data by locating and retarding redundant or repetitive image signals, thereby freeing up bandwidth or disk space for moving images.

Progressive Scan-

Progressive scan adds three dimensional and flicker free picture quality. A progressive display produces an entire frame of all visible lines of resolution, rather than the interlaced format of displaying odd lines on one frame followed by even lines on the next frame. Progressive scan devices also process information at a higher rate, which allows for a high color resolution.

Super Audio CD (SACD)-

A new aural scheme from Sony and Philips, the original inventors of the compact disc that adds a much more robust musical format than that of the standard CD. An SACD has a sampling rate of 2 882 400Hz, 64 time higher than that of a standard PCM CD at 44 100Hz. Additionally, the frequency response has been broadened to 100Hz, allowing you to hear a much broader detail of the music.

Surround Sound-