HDTV = High Definition TeleVision
SD = Standard Definition
TWC = Time Warner Cable
STB = Set Top Box: piece of hardware that converts the
OTA = Over The Air: method to receive digital TV programs via an antenna and digital decoder.
DVR = Digital Video Recorder: a VCR like device that digitally records TV programs on a computer hard drive.
1080i -- 1080 horizontal lines that are displayed in an interlaced fashion.
480i -- 480 horizontal scan lines that are displayed in an interlaced fashion. This is also known as SDTV or standard definition television.
480p -- 480 horizontal scan lines that are displayed progressively. This is not "High Definition", but is instead called Enhanced Definition TV (EDTV). This is the resolution that DVDs are encoded at.
720p -- 720 horizontal scan lines that are displayed in a progressive fashion.
Aspect Ratio — The ratio of a picture's horizontal resolution, measured in either pixels or lines, to a picture's vertical resolution, also measured in either pixels or lines. Aspect ratio is always measured in width to height (e.g., 16:9). Standard screen televisions have an aspect ratio of 4:3. Widescreen television have an aspect ratio of 16:9 and allow for a more panoramic viewing experience.
ATSC - The Advanced Television Systems Committee, Inc. (ATSC), is an international, non-profit membership organization developing voluntary standards for the entire spectrum of advanced television systems. Specifically, ATSC is working to coordinate television standards among different communications media focusing on digital television, interactive systems, and broadband multimedia communications. ATSC is also developing digital television implementation strategies and presenting educational seminars on the ATSC standards.
Broadcast Flag -- A broadcast flag is a set of digital bits sent with a TV program to prevent digital copying of the content on the consumers end. It will not change the way you see a program, but instead will be hidden to the viewers eye. Broadcast Flags were initially created by Fox, but soon thereafter adopted as a part of the ATSC standards. The MPAA is pushing the FCC to implement broadcast flags so they can allow stations to broadcast their content without the fear of people making their own personal, digital copies.
Component Video — A set of three physical connectors (typically red, green, and blue RCA jacks) that are used to transmit or receive component video signals. Component video signals are high-bandwidth signals that separate the Luminance and Chrominance signals of a video picture for enhanced resolution and color fidelity.
Direct View Display — A direct view television uses a cathode ray tube (CRT) to produce picture images on the display screen. Three electron guns at the rear of the television fire beams at the phosphor-coated interior of the display screen. Each gun causes the phosphor to glow red, blue or green, causing a colored dot to appear on the screen. Since direct view displays are phosphor-based, they are susceptible to screen burn.
Downscaling — A process by which a program is converted to a lower resolution than its native format for display on a television. The process may also involve a conversion between progressive and interlaced scan formats. Downscaled content is typically less crisp and clear than its native resolution.
DTV — Television signals that are recorded, broadcast, and processed digitally. Currently, 18 different DTV formats have been specified, including SD and HD formats. DTV broadcasts are sharper than analog broadcasts and offer much better noise immunity and resistance to degradation.
DVI — Digital Visual Interface. This is a high-bandwidth video connection that carries digitized RGB picture information and can support copy-protection methods. The DVI specification allows for the presentation device and display device to agree on an optimal picture size and resolution to ensure the highest quality picture automatically.
EDTV — DTV signals that feature roughly the same resolution as SDTV signals but are drawn exclusively using progressive scan methods. Since these signals do not offer the additional resolution, they are not considered HDTV. But, because they offer a smoother picture and less flicker than interlaced SDTV signals, they are referred to as Enhanced Definition signals.
FireWire -- See 'IEEE 1394'
Frame — As it relates to a video image on a television screen, a frame is comprised of all of the horizontal and vertical pixels (lines) at one time. A complete picture is known as a frame.
HDTV — DTV signals that feature greater vertical and horizontal resolution compared to SDTV signals and are presented in a widescreen (16:9) format. HDTV pictures have twice the color resolution and roughly six times the sharpness of SD images.
IEEE 1394 -- This was meant to be an enabling technology that would allow all things in your home theater to connect using this compressed digital interface. IEEE1394 (aka FireWire) makes allowances for 5C which would allow original broadcasters the ability to choose which type of copy control they want to use. The options given to broadcasters are: Allow copying; allow copying only once; or no copying allowed.
Interlaced -- HDTV is scanned in two different ways, one being progressive and the other being interlaced. Interlaced scanning is when the TV uses two separate passes to make an image on the TV. The first pass will display the odd horizontal lines such as 1, 3, 5, 7 and so on. On the next pass it displays the even lines such as 2, 4, 6, 8 and so on. Since this is done so fast the human eye sees this as being one picture instead of two. After the second pass the third will go back to displaying the odd lines, then even again and so on.
Letterbox Mode — A method of presenting widescreen images on a standard screen television. In order to preserve the aspect ratio of the original video content, the picture is scaled down so that it fits the available width of the television screen. Since the picture will not fill the screen vertically, dark bars are drawn in above and below the picture.
Liquid Crystal Display — An LCD television or monitor uses liquid crystals that act as "shutters" within the television screen. An LCD television has thousands of small light sources at the rear of the display. A layer of cells containing the liquid crystals is placed between the light sources and the display screen. When the liquid crystal cells are electrified with current, the crystals align and block any light from shining through, or scatter allowing the light to shine through to the screen. LCD monitors typically only display video signals in a progressive scan format. LCD monitors do not use phosphors and are not susceptible to screen burn.
Multicasting -- This is the process of transmitting more then one program over the air at the same time on the same channel. When stations are given their channel for DTV broadcasting they are allocated a specific amount of bandwidth. If they are not using the full amount of bandwidth, they can squeeze more programs OTA through that same channel. These channels are denoted by hyphens, such as 29-1, 29-2 and so on instead of what you might be used to as one channel on 29. Some stations are broadcasting one SDTV and one HDTV channel without much picture quality loss in the High Definition program.
Native Resolution -- Usually describes the actual resolution of the display device. If you see native resolution used with LCD, DLP, dILA or Plasma, this will be an exact number. With CRTs, this number is an approximation. Either way, if you see a Max Resolution for the display device, your device will simply scale the image down to it's native resolution. See Scaling / Doubling for more information on that subject.
NTSC -- NTSC is the National Television Standards Committee and was responsible for developing a standard protocol for broadcasting TV signals in 1953. Not many changes have been made to this protocol since its creation except the addition of new parameters for color broadcasts. The NTSC broadcast has 525 horizontal scan lines which are drawn in an interlaced fashion. The result is one frame every 1/30 a second.
O&O -- Owned and Operated. These are the local affiliates of major networks that run in your area. These stations probably include FOX, ABC, CBS and so on.
Pillarbox Mode — A method of presenting standard screen images on a widescreen television. In order to preserve the aspect ratio of the original content, the picture is scaled so that it fits the available height of the television screen. Since the picture will not fill the screen horizontally, dark bars are drawn in to the left and right of the picture. Pillarbox presentation is also referred to as "Curtained" or "Sidebarred" modes.
Pixel — The term "pixel" comes from the phrase "picture element" and is equivalent to a dot on a screen. High-Definition pictures are comprised of many more horizontal and vertical colored dots than standard definition pictures. In the DTV world, pixels are broadcast as either square-shaped or rectangular-shaped pieces of the total picture.
Plasma Display — A plasma television uses hundreds of thousands of tiny cells embedded in the screen to produce a picture. Each cell represents a pixel, and each cell is comprised of three subcells. The three subcells are filled with plasma gas that glows either red, blue, or green (depending on the phosphor coating) whenever it is electrically excited. The colored light emitted by the three RGB subcells combine to form a single colored pixel on the screen. Since plasma displays use phosphor, they are susceptible to screen burn.
Progressive -- HDTV is scanned in two different ways, one being progressive and the other being interlaced. Progressive scanning is done the way you would expect a TV image to be shown. Each horizontal line is displayed right after the previous one. The lines are scanned in order from top to bottom so that it goes 1, 2, 3, 4, 5, 6 and so on. This means the image is displayed in one pass instead of two as it is done with interlaced scanning.
Projection Display — A projection television uses an internal video projector (either LCD or CRT) to create a small version of the picture image, which is then magnified and projected onto a large viewing screen. Projection displays are used to create very large screens, but their sharpness and clarity can be very adversely affected by the viewer's position relative to the screen. Since the video source inside a projection television uses phosphors, the video source itself is susceptible to screen burn.
QAM -- Quadrature Amplitude Modulation. This is an efficient way of transferring binary data over cable. It is used for multiple dwelling unit installations. They set up a few LNB dishes and send the output to a QAM converter rack. Then they send the signals into the cable entering the apartment building. The people wanting to receive these signals connect their satellite receiver to the cable and they can then receive satellite TV. The downfalls are that mostly everyone working for the satellite company knows nothing about it. Also, misalignment of a dish will affect everyone and you probably don't have direct access to re-align that dish.
Resolution -- Resolution is described by the number of pixels that are on a display monitor. (aka the individual points of color) When you see a resolution of 640 x 480, the first number always represents the number of pixels on the horizontal axis, with the second number representing the number of pixels on the vertical axis. The clarity of the image is in direct correlation to the resolution vs. the size of the display. Thus, if you have a high resolution on a small monitor, then you have a very sharp picture.
RGB -- RGB stands for Red, Green, Blue and is a way of transmitting signals in three seperate channels - each one dedicated to each of the colors. RGB is the opposite of 'Composite Video' because composite video combines each of the signals during transmission.
Screen Burn — Screen burn is a condition that can arise when significant portions of a television screen are not used to display active video for prolonged durations of time. This can occur when 4:3 pictures are constantly presented on a 16:9 television screen, or 16:9 pictures are constantly presented on a 4:3 television screen. The pixels in the dark sidebars are not exercised and wear much less rapidly, so that when the full display is finally utilized, there are noticeable differences in the brightness and clarity of the unexercised pixels. In addition, bright images that remain stationary on any screen that uses phosphor technology to generate the image can become burned into the screen, resulting in an annoying "ghost image" that remains permanently on the screen.
SDTV — DTV signals that feature vertical and horizontal resolutions comparable to current NTSC analog television signals, typically using a standard 4:3 aspect ratio. SD programs are drawn using interlaced scan methods. For the most part, all HDTV monitors are capable of supporting an interlaced SDTV (480i) signal, some also support 480P.
Simulcast -- The process of simultaneously broadcasting on two different channels, aka paths. When it comes to DTV, this means the station is most likely broadcasting the same thing in standard definition format and in a DTV format.
STB -- STB stands for set-top-box and is the receiver you use to decode high definition signals. STBs are often called a ‘decoder’, a ‘receiver’, or a 'tuner'. The term decoder is the more appropriate term as the word receiver can often mean the stereo equipment component.
Upconverting -- The process of taking a SDTV image and enhancing it to look better on a high-definition monitor.
Upscaling — A process by which a program is converted to a higher resolution than its native format. The process may also involve a conversion between progressive and interlaced scan formats. Upscaled content can look fuzzy or distorted compared to its native resolution.
Wide Screen -- The term used to describe a screen that has an aspect ratio that is wider then the NTSC 4:3 ratio. Most HDTVs and EDTVs have an aspect ratio of 16:9 as do most major motion pictures. When motion pictures are converted to NTSC television the image is squeezed and cropped so it will fit the smaller, 4:3 screen.
YPbPr — YPbPr represents component video connections, where luminance (Y) is represented by a green jack, separate from the color components blue (Pb) and red (Pr). Most high-definition sets today support this format. These colors should not be confused as RGB output.
