Glossary
Aspect ratio. The ratio of screen width to screen height. For TV it is either 4:3 ("standard") or 16:9 ("widescreen"). Movie theaters use a number of different aspect ratios, some even wider than 16:9.
ATSC. Advanced Television System Committee technical standard. This is the digital replacement for the old NTSC standard, used by terrestrial digital TV stations in the U.S.
CableCARD™. A technology adopted to prevent cable piracy. Companies will periodically mail out new cards to their customers and then disable the old cards, so anyone without a current card will lose service. The card usually resides in a set-top box, but newer HDTVs may include a cableCARD slot.
Color temperature. Describes how white is displayed. Low temperature means slightly reddish, while high temperature means slightly bluish.
Component video. A 3-plug system designed for connecting DVD players to TVs or monitors. It avoids downgrading the signal to NTSC. The signals may be RGB or Y/Pr/Pb.
Composite video. This 1-wire standard contains all video information: intensity, color, and sync. Obsolete in HDTV.
D-ILA. Direct-drive Image Light Amplifier. (see LCoS)
DLP. Digital Light Processor. A technology for video projection, also call DMD (Digital Micro-mirror Device). It is a large chip with about a million tiny mirrors on its surface. The chip can tilt each mirror to vary the amount of light reflected off of it.
DMD. Digital micro-mirror device. (see DLP)
Dolby Digital 5.1. Also known as AC-3, it provides 6 channels of sound: left, center, right, left rear, right rear, and subwoofer. It is also called "5.1 channels" since the 6th channel (subwoofer) has reduced bandwidth. Dolby Digital 5.1 is the audio standard for all U.S. digital TV stations, most DVDs, and many theaters.
Dolby Pro Logic Surround. This is a 4-channel analog system. During recording, the 4 channels are "folded" into 2 stereo channels. If played back without a Pro Logic decoder, it sounds like normal stereo. This format is becoming obsolete.
DTCP (Digital Transmission Content Protection). This is an encryption standard for IEEE 1394 that prevents the copying of first-run movies and pay-per-view events. DTCP is also called 5C Copy protection.
DTV. Digital TV. Examples of DTV are direct-broadcast satellite services, digital cable TV services, and ATSC digital TV stations. Not necessarily HD.
DTVLink. A mark sometimes seen on equipment employing IEEE 1394 (FireWire) and DTCP decryption.
DVI. Digital Visual Interface. A connector that conveys HDTV image signals in binary form. Binary data is preferred by monitors that are not CRTs. DVI comes with a decryption option called HDCP which will decode protected content. Rapidly being replaced by HDMI.
EDTV. Enhanced Definition TV. Essentially DVD quality, it is a small step up from NTSC. An EDTV will convert ATSC formats to 480p.
FireWire. (see IEEE 1394)
HDCP (High-bandwidth Digital Content Protection) Developed by Intel, this is a decryption system used with HDMI and most DVI connections. It will decode protected content such as first-run movies.
HDMI. High-Definition Multimedia Interface. A 19-pin digital connection that includes both HD video and multi-channel audio. It uses the HDCP decryption system.
HD-Ready. An HDTV monitor or TV that lacks a digital tuner.
HDTV. High Definition TV. A TV that displays 1280x720 pixels or better.
IEEE 1394. Also called FireWire or i.link. Originally a serial bus for PCs, 1394 is used as a connection for some HD products.
Interlaced scan. Interlaced means that the signal beam skips every other horizontal line, filling in the missing lines on the next pass.
LCD Liquid Crystal Display. A display technology.
LCoS Liquid Crystal on Silicon. A display technology.
MPEG-2. Motion Picture Experts Group technical standard 2. This is a widely used standard for digital encoding of motion pictures. It typically achieves a 50 to 1 compression of data. It achieves this mainly by not retransmitting areas of the screen that have not changed since the previous frame.
MPEG-4. Motion Picture Experts Group technical standard 4. An improved standard for digital encoding and compression.
NTSC. National Television System Committee technical standard. This is the analog TV standard invented in 1946. Historically used in North America, Japan, South Korea, Burma, Taiwan, the Philippines, and much of South America.
OTA. Over The Air. Refers to terrestrial broadcast TV stations.
PAL. Phase Altering Line standard. This alternative to NTSC has historically been used in most of Europe, Asia, Africa, and Australia, as well as parts of South America.
Progressive scan. The alternative to interlaced scan. Frame rate is effectively doubled.
Repeater. An electronic device that receives a signal and retransmits it at a higher level or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances without degradation.
SDTV. Standard Definition TV. (see NTSC)
SECAM. Sequential Color And Memory standard. This alternative to NTSC has historically been used in the former USSR, France, parts of Eastern Europe, the Middle East, and Africa.
Sink. A device, such as an HDTV, that receives a high-definition signal.
Source. A device, such as a DVD player or Set-Top Box, that sends a high-definition signal.
STB. Set Top Box. A broad term that includes satellite receivers, cable TV receivers, OTA receivers, and various recording devices.
S-video. This two-wire standard has quality similar to that of component video, but cannot transport anything better than 480i. Obsolete.
Toslink. A fiber optic cable standard, used to transmit digital audio data.
VGA. A 5-wire interface, originally for computer monitors, now used in some HDTV monitors. Usually the 5 wires are in one cable.
3:2 pull-down. This is the process of converting a 24 frames/sec image into a 30 frames/sec image.
5C Copy Protection. See DTCP.