Y/C is a type of video connection. The Y stands for luminance and the C stands for chrominance. Y/C, commonly called S-video, is a type of video signal that separates the color portion of the signal (chrominance) from the brightness portion of the signal (luminance) resulting in higher picture quality compared to composite video, which combines the two into a single signal.
S-video eliminates the need for a comb filter or a notch filter and provides a better picture than a composite connection. If you use an S-video connection, you need a separate cable for the audio.
Universal Remote Control
A universal remote control can be programmed to operate several components. Instead of using a separate remote for each component, you can use a universal remote to control them.
Tint is a color attribute based on a primary color. Tints are made by mixing a primary color with either black or white.
Toslink (SPDIF) is a type of fiber-optic cable connection that uses light beams to transmit information between digital audio components.
Using fiber-optic cables to transmit digital information avoids potential interference from electrical wiring and other electrical devices that can interfere with traditional metal cables carrying electrical signals.
Treble refers to high-frequency sounds with short wavelengths. The tweeter usually handles treble sounds in an audio system. Treble is the opposite of bass, the low-frequency sound waves.
TruFlat™ Picture Tube
TruFlat is a flat screen picture tube designed by RCA to provide distortion-free viewing for HDTV, digital broadcast and other emerging formats.
Truscan Digital Reality™
This is a process used in RCA digital TVs to progressively convert incoming signals to achieve the best digital picture.
A tuner is an electronic device used to receive and decode signals that can be played on video and audio systems. Tuners are primarily used for television and radio reception.
Televisions are video displays with tuners built in. Television tuners receive video signals from terrestrial, cable, or satellite sources and transmit them to a video display for viewing.
AM and FM tuners decode amplitude modulated and frequency modulated radio signals, respectively, to generate audio information.
A tweeter is a speaker driver used to reproduce high-frequency sound. Tweeters are small in size because the sound waves they reproduce are small.
Tweeters are combined with midrange and bass drivers (woofers) to reproduce the full audible spectrum.
Wide Band Video Amplifier
A wide band video amplifier is a high resolution video amplifier used in some RCA video displays.
Widescreen refers to a video format that is similar to movie format; widescreen is more rectangular the broadcast formatting, which uses the almost-square 4:3 NTSC format. The terms "16:9" and "widescreen" are sometimes used interchangeably, although 16:9 is only one of many widescreen aspect ratios.
A woofer is a speaker driver that handles the low-frequency signals of a sound wave.
V-Chip is a feature that allows you to program your TV so that children can’t see certain programs or channels. You can block programs based on violence, sexual content or other content you do not want your children to watch.
V-chip software reads a code that most broadcasters send with programs. The code contains an age-based rating and content rating (not all programming is rated). You can choose to block those programs with ratings you don’t want your children to see.
Vertical resolution refers to the number of horizontal lines that a video display can paint to create one frame or image. Higher resolutions (more lines) produce better quality pictures. Television resolution is often stated in vertical resolution.
The NTSC (analog) television standard used in the United States has a vertical resolution of 525 lines. Of these, 43 lines are used to carry other information, such as closed captioning text and on-screen guide information, so the true maximum vertical resolution for NTSC is about 480 lines.
Vertical resolution for high definition television is set at either 1080 interlaced lines (1080i) or 720 progressive scan (non-interlaced) lines (720p).
The video input is a connection jack (or plug) on an electronic component that receives electronic signals (with video information) from a wire, or cable, sent by another component.
The video output is a connection jack (or plug) on an electronic component that sends electronic signals (with video information) through a wire, or cable, to another component.
A patch cable is a low-level connection cable used to transfer information in an electronic form between components in an audio/video system.
Parental Controls is a feature that allows you to program your TV so that children can’t see certain programs or channels. You can block programs based on violence, sexual content or other content you do not want your children to watch.
Perceptual coding is a method of reducing the amount of data in an audio or video signal by eliminating or reducing the data that human senses cannot perceive. Many compression techniques use perceptual coding to reduce signal size without loss of quality.
Persistence of Vision
When an image is flashed before our eyes, our brain holds it for a short time. If a second image follows close behind the first, our brain blends the two images. By flashing enough images in quick succession, the brain perceives the image stream as motion. This is the principle behind movies and television.
PAL is the television broadcast standard developed in England and Germany that is used in many South American, European and Asian countries. The PAL standard is not compatible with the NTSC standard of the United States or the SECAM standard of France, Russia and other countries.
PCM (Pulse Code Modulation)
PCM is a common form of transferring analog information into digital signals by representing analog waveforms with a stream of digital bits. The digital information can be manipulated and translated back into an analog signal with a digital-to-analog converter.
Digital information can be manipulated more easily and with less distortion, but in order to recreate sound, digital signals must be converted back into an analog signal.
A phosphor is an element that emits light (red, green and blue light as used in video displays) when bombarded by electrons. Phosphors are placed on the backside of a cathode ray (picture) tube’s glass or plastic screen. The tube’s electron gun emits electrons, which are aimed at particular phosphors. The phosphors are excited by the electrons to glow, or give off light.
The red, green and blue phosphors are placed together in a phosphor triad. These color triads make up the pixels of a video display.
A picture tube, also called a CRT, is a common type of video display. A picture tube is a large vacuum tube with a slightly curved glass surface at one end (the screen) and an emitter of electrons on the other. The emitter focuses and directs a stream of electrons to a coating of phosphors on the back side of the TV screen.
PIP is a feature found in some televisions that lets the viewer to watch one program on the entire screen while displaying a different program in a small window superimposed over the base program.
Picture-in picture requires two video sources. Some PIP-equipped televisions come with two tuners (one for the PIP window and one for the main program filling the screen), while others rely on an external tuner from another component to supply programming to the picture-in-picture window.
PIP allows you to watch a particular program while also searching through other channels or content in the PIP window (or vice versa).
Pixel is short for picture element. A pixel is the smallest individual unit or piece of a video image. A complete video image is formed by many thousands (sometimes millions) of pixels. Each pixel has its own color and brightness attributes.
The number of pixels in a display defines its resolution; higher resolutions have more pixels. The more pixels, the greater the resolution and quality of the image.
The sampling rate is the number of samples or “snapshots” taken of a particular signal in a given amount of time (usually one second). All analog data converted to digital data is sampled. The samples are then given a value that can be stored digitally. Later, the samples are recreated from the digital data and blended to form a complete, continuous analog signal (this is the job of the digital-to-analog converter or DAC).
Higher sampling rates result in more pieces of the true signal. When a sufficient number of pieces are generated, the pieces meld together to form a very close approximation of the original, continuous analog signal.
Saturation is the amount of pure color (depth and intensity) being displayed, based on how much white is present in proportion to the pure color. For example, a deep red has a high level of saturation (mostly pure red with little white), while light pink has a low level of saturation (a small amount of pure red and a high level of white). Most video displays have a saturation adjustment. If the saturation level is set too high, the colors will be too strong and bold. If saturation is set too low, the colors will be washed out.
A scan line is a single horizontal line on a video display which, when combined with other lines on the screen, creates a complete image. Scan lines are “painted” onto a display screen one at a time at an extremely fast pace. The more scan lines presented, the better the picture quality. Increasing scan lines increases the vertical resolution of a picture.
Scan rate is the speed at which a video display paints scan lines onto a screen. Also referred to as picture rate or refresh rate.
Scan Velocity Modulation
Scan velocity modulation is a technique employed on some cathode ray (picture) tube television sets for slowing down or speeding up the electron gun as it scans or paints each horizontal line of information. The beam is slowed down to reproduce areas of bright light, and sped up on areas of low light or low brightness.
Scan velocity modulation is sometimes listed as a valuable feature, but it can cause picture distortions. Look for a television that allows you to turn this feature off.
SDTV (Standard Definition Television)
SDTV includes 12 accepted quality forms of the digital television standard adopted for the United States. SDTV features AC-3 digital surround sound, wide (16:9) and “square” (4:3) aspect ratios, and high-quality (not high-definition) digital video.
The nature of DTV (digital television – the television standard that encompasses the 6 forms of HDTV and the 12 forms of SDTV) eliminates many of the problems encountered with analog televisions, such as “snow,” poor color reproduction, color bleeding, etc. SDTV uses AC-3 encoded sound, resulting in the ability to transmit excellent quality surround sound audio in a 5.1 digital format.
The wider aspect ratio featured with some forms of SDTV (16 units wide by 9 units tall, or 16:9) allows movies to be presented in their full width. This will also result in “wide” television programming, presenting television shows in a more movie-like format.
Due to the smaller bandwidth needed to broadcast SDTV signals compared to HDTV signals, it’s possible to broadcast multiple SDTV programs over a single HDTV channel. This is known as multicasting. It results in lower picture quality (compared to HDTV) but offers more channels to choose from.
A set-top box is a receiver that connects to a video display and receives and decodes video and/or audio signals. Also known as a receiver or tuner.
SMPTE (Society of Motion Picture and Television Engineers
The SMPTE maximizes/sets standards for video reproduction in theaters and at home, sets video standards and provides test materials, disseminates information for the betterment of video/image production and reproduction, and advances video technology.
Sound Logic is a feature in some TVs that keeps the volume level consistent during programming and channel changes. For example, sometimes commercials are louder than programs – Sound Logic adjust the volume so the volume level you set applies to all channels and programming.
Solid state is a type of electronic component composed of transistors and integrated circuits that use no vacuum tubes. Solid state electronics are the primary form of electronic components. They are reliable, low in distortion, cool running compared to vacuum tubes, efficient, and easy to produce.
Cathode ray tubes, used in many video displays, are special forms of vacuum tubes. However, most modern televisions also contain solid state electronics.
RGB stands for the three additive primaries – red, green and blue – that combine to form the color spectrum.
An RCA connector is a type of standard, low-level signal connection termination or connector. RCA-type cables are used for connecting many types of video and audio components.
The RCA V-port is a jack that enables you to directly connect an X-box to the TV. This jack comes only on RCA TVs.
Rear Projection Video Display
Rear projection is a type of video display. With the rear projection screen, light hits the screen from behind and shines outward instead of hitting it from the front and bouncing back into the room.
Most rear projection televisions contain at least one tuner and many also feature picture-in-picture and other enhanced features. Rear projection displays are easy to set-up and cost less than front projection systems.
A receiver is a component (either audio or video) that receives and decodes a video or an audio signal (e.g., satellite receivers, HDTV receivers, audio receivers, etc.).
The refresh rate, or vertical scan rate, is the number of times a video display can paint an entire image with a video signal. The standard refresh rate for video (television, DVD, VHS, laserdisc) is 60 Hz. This means that the display redraws the image 60 times in a second.
The maximum vertical resolution of a video display (the number of horizontal lines drawn) can be determined by dividing the horizontal scan rate by the refresh rate (the vertical scan rate).
Resolution refers to the number of elements (pixels) used to create an image. In digital video and audio, resolution refers to the number of bits of information that recreate a signal.
Higher resolution provides higher quality.
RF (Radio Frequency)
Radio frequencies are used for broadcasting video, audio, satellite, cellular phone signals, radio telescopes, emergency beacons, and much more. Located above the radio frequency (at higher frequencies) is the infrared electromagnetic spectrum, and above that is the visible light spectrum.
Matrix Surround Sound
Matrix surround sound is a method of encoding several audio channels into a pair of analog audio channels. The sound is encoded during production and decoded by a surround sound processor.
Since the channels in a matrix surround sound system are not independent, they tend to interact with and bleed into one another. Analog matrixed sound does not have the high level of quality found in independent digital formats.
Midrange refers to the middle band of audio frequencies. The human ear is most sensitive to the midrange area of the frequency spectrum. Human speech falls in the midrange, making it one of the most important areas for sound reproduction.
A moiré (pronounced (more-ay) pattern is a form of video image distortion created when multiple screen-like patterns are superimposed over one another, producing a screen door effect.
A monitor is a video display that has no tuner. It can only display information sent to it from other connected video components.
While televisions often are referred to as monitors, televisions contain built-in tuners.
Mono, or monaural, means one. A movie with a mono soundtrack has only one channel of audio information. A mono amplifier has only one channel of output.
Monochrome means a single color.
MPEG-1 is a video compression format developed by the Motion Picture Experts Group. MPEG-1 eliminates data from an audio/video signal by removing information that cannot be perceived (or is difficult to perceive) by human senses, making the signal smaller in size. MPEG-1 compression is used when quality is not the primary issue. MPEG-1 is inferior to MPEG-2, which is used with DVD, DBS and HDTV.
MPEG-1 compresses video to a much smaller size; however, when MPEG-1 video is played back on a video display, the images are only slightly better than VHS quality.
MPEG-2 is a high-quality audio/video compression format developed by the Motion Picture Experts. MPEG-2 is used for DVD, DBS (direct broadcast satellite) and HDTV.
MPEG-2 offers improved compression compared to MPEG-1. MPEG-2 eliminates data that cannot be perceived (or is difficult to perceive) by human senses.
MPEG-2 does not compress video to the same degree as MPEG-1, so the signal is a bit larger. However, superior quality and flexibility make MPEG-2 a preferred format that is becoming an industry standard.
LED (Light Emitting Diode)
An LED is a solid-state type of video display that is used to provide information on the status or operation of audio/video components.
A line conditioner, or surge protector, is an electronic device that “cleans” the electricity coming from a wall outlet. It protects audio/video components from electric spikes and surges that can cause damage to the components. The line conditioner plugs into a standard wall outlet, and audio/video components are plugged into outlets on the line conditioner.
LCD (Liquid Crystal Display)
LCD is a type of video display using liquid crystals sealed between two pieces of glass. Liquid crystals change the amount of light they allow to pass through them when an electric current is applied.
Because LCD video displays don’t require a tube, they are thin and flat. While their profile is thinner, the picture degrades when the screen size gets too large, so smaller LCD displays provide a better quality picture.
Learning Remote Control
A learning remote control is a type of remote control that can learn commands from other remote controls. Learning remotes can be taught a wide range of commands. They are able to duplicate all the functions of most other remote controls, allowing them to replace a group of remotes with a single remote. A learning remote can operate several types of components.
Letterbox is a video display format (used mainly for DVDs) with a widescreen aspect ratio, similar to a movie screen. Movies are shot in widescreen format, and designed to be shown in a theater. When a movie is displayed on a standard (4x3 aspect ratio) TV, if you fit the image to the height of the television, the image is too wide for the TV screen, which means the sides of the image are cut off. Letterbox format fits the image to the width of the screen, so the entire picture is shown. However, the picture does not fill the height of the television screen, so black bars fill in the extra space above and below the image.
A line doubler recombines the odd and even fields of a frame into one sequential, progressive signal. This signal is much cleaner and produces a better image. In addition, the lines are displayed in half the time, so the line doubler displays the same frame a second time, which increases image brightness and stability.
The result is an image with more greater detail and clarity than a traditional, interlaced video image.
Some TVs have line doublers built in.
Line level is a term for a low-level signal sent over cables that connect components in an audio/video system. Line level signals transfer information from a component to an amplifier. The amplifier’s job is to take the line level signal and expand its power.
Low Noise Pre-amplifier
Some RCA TVs include a low noise preamplifier, which minimizes both audio and video “noise.” Pre-recorded movies sound richer, cleaner, and more distinctive.
A lumen is a measurement unit of illumination. Lumens are often stated in video display specifications. Higher values mean that the display is able to output more illumination, or more light. With higher light output, a video display is easier to see in a brightly lit room. This is especially important with front projection systems, which usually work better in dim lighting.
Luminance is the portion of a video signal, which carries the information for brightness, darkness and contrast. Luminance ranges from pure black to pure white. Luminance is combined with the color portion (chrominance) of the signal to form a complete video image.
The chrominance portion of the signal tells a video display what color to show. The luminance value adjusts the color to be light or dark, bright or shadowed, so it has the proper contrast and color depth. Chrominance is abbreviated with the letter “C” and luminance is abbreviated with the letter “Y.”
Off-air refers to broadcasts transmitted over the airwaves (instead of via cable or satellite) and received by antenna. Off-air is also referred to as terrestrial or over-the-air (OTA).
On-Screen Channel Labeling
On-screen channel labeling is a feature on some RCA TVs. It enables you to customize visual information (6 letters and 3 numbers) for up to 70 channels. When you tune to one of those channels, the information is displayed for 6 seconds.
On-Screen Clock, Sleep and Wake timers
Some TVs offer a clock feature that enables you to turn the TV on and off at selected times, e.g., when a program is beginning or ending.
An optical cable is a connection cable that uses bursts of light carried over glass or plastic fibers to transfer data between digital components.
“Noise” is low-level interference in an electronic component resulting from a power supply hum, internal electrical components, or other sources. Noise may also be in the form of radio waves or other signal distortions. Noise is found in all electrical components.
Solid-state electronics tend to have less noise problems than vacuum tube-based components.
The lower the noise rating of a component the better. When looking for an audio/video component, pay attention to the signal-to-noise (S/N) ratio to determine the amount of noise in the component. The S/N ratio is measured in decibels (dB). The larger the S/N number the better.
Also known as progressive scan, non-interlaced refers to the way a video image is displayed on-screen. Each line of a non-interlaced frame (one complete image) is drawn one line after the other, i.e., progressively. This differs from interlaced images that draw the image in two fields where the odd lines are drawn first and then the even lines are drawn to create the final frame or complete image.
Interlaced video is used for the analog NTSC broadcast television standard in the United States. Both interlaced and progressive scan video are used for digital ATSC broadcast television in the United States.
Some DVD players offer progressive scan, but you must have a TV with a component video (RGB or Y, Pb, Pr) connection to take advantage of this capability.
A notch filter separates chrominance (color) information from the luminance (brightness) information in a composite video signal. A notch filter or comb filter must be used to separate the color and brightness portions of a composite video signal.
A comb filter is better than a notch filter because it provides better resolution and less distortion. Most higher quality video devices use comb filters.
NTSC (National Television Systems Committee)
NTSC is the U.S. government agency that established the analog color television standard in use since 1953. The NTSC standard currently is being replaced by the new digital television standard (ATSC) advocated by the FCC.
NTSC video is transmitted in an analog format using a nearly square 4:3 aspect ratio, providing 525 horizontal lines of maximum resolution. It is an interlaced format that creates two separate fields, one every sixtieth of a second, and combines them to form one complete video frame thirty times per second.
The other video formats commonly used throughout the world are PAL and SECAM.
Infinifocus CRTs are picture tubes with color filter lenses and Intellifocus™ digital auto convergence that display a bright, automatically aligned video image.
Many audio/video components come packaged with cables.
Integrated HDTV means there is a digital turner built into the display, so the display can receive over-the-air DTV signals without a separate receiver (set-top box).
An interconnect is another term for the cables used to connect video and audio components. Cables come in a variety of lengths. Each cable has some form of termination at both ends. The termination, or connector, is what actually connects to the inputs and outputs on a component.
The common terminations for video cables are RCA (composite video), S-video, and F-type (used with coaxial cable for cable TV, antennas, etc.). The most common terminations or connectors for audio cables are RCA (most widely used), XLR, and Toslink (fiber-optic).
Many audio/video components come packaged with cables.
Interlacing is a method of combining two fields of information to create one complete image, or frame. The first field contains the odd lines of information, and the second field contains the even lines of information. The first field, with the odd-numbered lines, is drawn first, and then the second field, with the even lines, is drawn second to complete the frame.
Interlaced video is the standard for analog NTSC video distribution. Digital ATSC video can be either interlaced video or progressive scan video.
Interlaced video is different from non-interlaced (progressive scan) video, which paints each line of the frame sequentially. The interlaced video method saves bandwidth, but it can result in a shakier, less detailed image.
Infrared (IR) light beams are invisible to the human eye, but are used in many remote control devices to transmit information and commands to components. IR works like other light beams, traveling in a straight line. In order for an infrared command to work, there must be a clear, unobstructed path between the IR emitter that is sending the signal and the component that is receiving the signal.
An IR emitter generates infrared (IR) light beams that transmit information and commands from one device to another.
The most common use of an IR emitter is in a remote control. The remote sends signals (invisible to the human eye) to a component, and the IR receiver in the component picks them up. When IR signals reach a receiving component they are deciphered, and the component performs the function you selected on the remote control.
HDMI (High-Definition Multimedia Interface)
HDMI is a digital video and audio connection system used to connect a variety of audio/video components, particularly high-definition video (HDTV). HDMI supports all HDTV formats (720p, 1080i, 1080p) along with support for up to eight channels of digital audio. HDMI transmits all digital signals without compression, allowing for superior quality without the presence of analog conversion artifacts.
HDMI is compatible with the DVI (Digital Visual Interface) standard as well as HDCP copy protection.
As a pure digital interface with high-bandwidth audio and video capabilities, HDMI provides the capability to transmit pure digital signals with just one wire compared to multiple analog connections that require potentially degrading digital-to-analog and analog-to-digital conversions.
High Contrast Picture Tube
A high contrast picture tube has increased contrast (more than traditional displays) that improves viewing in brightly lit rooms.
HDCP (High-Bandwidth Digital Content Protection)
HDCP is a specification used to encrypt and protect digital video and audio signals transmitted between two HDCP-enabled devices. HDCP was developed by Intel to provide a way to "lock down" digital signals and protect copyright holders (movie studios, etc.) from having their programs copied and shared. The HDCP standard provides for the secure, encrypted transmission of signals.
Horizontal Scan Rate
The horizontal scan rate is the number of horizontal lines of information a video display can paint on a screen in one second (measured in Hz).
Hue is the distinction or difference between colors ranging from red to blue. Black, white and the levels of gray in between are not considered hues. Hue and saturation are the two parts of chroma, the color portion of a video signal.
HDTV (High Definition Television)
HDTV is a high resolution digital broadcasting format that is close to film quality.
Compared to regular TV broadcasting, HDTV images contain about six times the amount of picture information, resulting in an incredibly detailed image. In order to fully take advantage of HDTV broadcasting, you need a video display that is capable of displaying high-resolution images.
HDTV is often confused with digital television. HDTV displays can be digital or analog; the difference is the video display’s resolution, or number of pixels it can display. An HDTV display does not have to be digital, and digital TVs are not necessarily high-definition.
HDTV is part of a digital television standard (ATSC) adopted for the United States featuring AC-3 digital surround sound, a screen with a wide aspect ratio (16:9), and two picture standards: 1080i and 720p. 1080i is interlaced video with 1,080 horizontal lines (vertical resolution) by 1,920 vertical lines (horizontal resolution). 720p is non-interlaced (progressive scan) video with 1280 pixels across (horizontal resolution) and 720 top to bottom (vertical resolution).
Home theater is a term used to describe a complete audio/video system consisting of a video display and surround sound (left, right and center front speakers and left and right rear). Home theater systems are designed to bring the movie theater experience into the home, and may be located in any room of the house.
Most home theaters use multiple video sources such as TVs, DVD players, VCRs, and direct broadcast satellite systems. Most also contain audio sources such as CD players, cassette players and tuners.
Horizontal resolution measures the individual picture elements (pixels) running along a screen from left to right. Vertical resolution measures the number of pixels from top to bottom. Higher resolutions result in images that are better defined and form a solid, cohesive image. With low resolutions, the individual elements of the image are more noticeable.
There are two primary HDTV standards, 1080i and 720p. With 1080i the resolution is set at 1920 pixels across (horizontal resolution) and 1080 pixels top to bottom (vertical resolution). The 720p standard provides for 1280 pixels across (horizontal resolution) and 720 top to bottom (vertical resolution).
KIDPASS is a feature offered on some RCA TVs which allows you to control the amount of time your child watches TV. You can set KIDPASS in 30-minute increments, up to 16 hours a day. KIDPASS is password controlled.
Jitter is quick fluctuations in a signal that result in distortion of video or audio output. Jitter in results in decreased picture quality or a slight shaking of the image on screen.
The Jack Panel is the group of connection jacks, or plugs, on the back of audio/video components. Sometimes jacks will be on the side or front of a component. This is where the components are connected.
On video components the jacks can include different types of video jacks (composite, component, S-video, DVI, HDMI, etc.) and audio jacks. The number and types of jacks that are on the component determine what you can connect to the component.
An electron beam is a flow of electrons generated in a cathode ray tube (CRT) by an electron gun. The beam is aimed at the back of the screen, where the electrons excite phosphors and cause them to glow in various colors.
EDTV (Enhanced Definition TV)
EDTV is a video display that uses progressive scanning (non-interlaced). Progressive scanning still displays 480 lines per frame, like interlacing does, but the lines are painted in order (1, 2, 3, etc.) in one frame. An interlaced frame is made up of two fields; the first field paints the odd-numbered lines, then the second field paints the even-numbered lines. Because progressive scanning paints an entire frame in one pass, image quality is much better than an interlaced image.
Decibels are most often used to describe sound pressure level (commonly referred to as volume). The term is also used in various other measurements such as signal-to-noise ratio, gain and dynamic headroom. In these instances, decibels refer the measurement of signal increase or signal strength instead of sound pressure level, but the scale and basic idea is the same.
Digital Surround Sound
Digital surround sound is a format in which all five audio channels (left front, front center, right front, right rear, left rear) are separate and full-range, recorded in digital audio, and compressed to fit in a smaller space. A subwoofer is an additional (optional) channel, but it is not full range.
Digital audio is a method of encoding analog audio signals into digital bits of information. Digital information is easy to transmit and record, and can be modified or adjusted quickly without signal degradation. The most common form of digital audio is the compact disc (CD). Digital audio can be compressed to save space.
DAC (Digital to Analog Converter)
A DAC is an electronic device that decodes digital data (ones and zeroes) into an analog signal that can be used by a video display to form an image. In the case of audio DACs, the analog signal can be amplified and played.
When an analog signal is recorded onto a digital medium, it is split up into thousands of very thin slices. Each of these slices is given a height and an order, and then the information is digitally stored. When digital signals are played back, the thousands of slices are lined up in the proper order. The digital to analog converter forms a solid, flowing line from the tops of the slices to create a continuous, analog waveform.
Most digital components include a digital-to-analog converter.
Digital refers to a type of signal, which is composed of individual bits, or chunks, of information. An analog signal is a continuous waveform signal. Digital signals are easier to manipulate and store, and have much less distortion than analog signals.
Digital television refers to video displays that can display digital video signals. ATSC, digital video broadcast standards, were adopted by the FCC to replace the analog NTSC format. This standard includes 18 formats; 6 high definition (HDTV) formats and 12 standard definition (SDTV) formats.
Digital television and high-definition television (HDTV) are not the same thing. Digital television refers to the type of video signal received and displayed, while HDTV refers to the image resolution displayed.
Direct View Video Display
Direct view is a video display in which the light produced by a cathode ray tube is viewed directly without being bounced off a screen (as in a projection TV). Direct view is similar to looking directly at the light coming from a flashlight instead of looking at the light as it bounces off the wall. Direct view displays have better light output than projection displays. Most televisions and computer monitors are direct view displays.
DLP (Digital Light Processing)
DLP is a digital video display technology. DLP rear projection video displays weigh much less than traditional displays e.g., a CRT or PTV) and are much thinner. Because of this, and because of DLP’s excellent image quality, DLP displays can be quite large.
DLP uses thousands (approximately 500,000) of tiny square mirrors. Each mirror represents one pixel, or picture element. Each mirror pivots on or off to reflect or not reflect red, green and blue light to create an image on the screen.
The mirrors are contained on a small microchip called a DMD (Digital Micromirror Device). Digital light processing systems are capable of displaying 16.7 million colors or true color.
DLP projectors may use one, two or three DMD chips. Three-chip designs split the three additive primary colors so that each chip reflects only one color of light. Three chip designs are the most costly but also output the most light with the highest quality.
One-chip designs use a single mirror for all three colors of light. The picture from a one-chip design is not as bright or detailed as the picture from a three-chip design.
Two chip designs have a higher light output than a single chip design, but are not as costly as a three-chip design.
The DLP system was developed and is licensed by Texas Instruments. DLP video displays are the highest quality currently available.
A dot is single spot or dot of phosphor found in a cathode ray tube (see CRT).
Dot crawl is picture distortion caused by poor filtering; a line of dots (single spots of phosphor on a cathode ray tube) shifts continuously where there is a sharp color separation in a vertical line. Most often, this occurs with composite video.
Gain (Projection Screen)
Gain is the amount a reflective screen reflects the light that is hitting it. A matte white screen has a gain of 1. Higher levels of gain send back more light, while lower levels of gain send back less light. A high gain screen makes an image more visible in bright light conditions; however, high gain screens may alter the color of the image. Most projection screens have gains of 1 or slightly more.
Gamma is the relationship between an original scene as filmed (the video input) and the how the image is produced on a video display. A linear gamma results in the video input looking the same when it’s shown on the video display. Non-linear gamma results in changes to the scene as filmed, so it looks slightly different on the video display.
Gamma correction accounts for the differences between the video input and the displayed image to create a more-identical reproduction of the original image. A non-linear gamma results in the video input not showing up exactly the same on the video display.
The geometry of a video display creates vertical lines that run parallel without bending or angling, and horizontal lines that run parallel without bending or angling. Proper picture geometry assures that an image does not vary in size across the screen and that it does not bend or warp.
A gray scale is the levels of gray ranging from true white to true black. The level of gray (or white or black) in a video signal is derived from the luminance portion of the signal.
A common type of cable termination used for cable television (CATV).
Fiber-optic cables use light beams to transmit information, as opposed to electrical signals, which travel over metal wires. Fiber-optic cables can be used to connect digital audio devices.
The greatest benefit of using fiber-optic cables in an audio system is their immunity to electromagnetic interference. They are not subject to the distortion that traditional metal wires carrying electric signals are.
A field is half of an interlaced video frame. A video frame is the entire image, consisting of two fields; one field contains all the odd horizontal lines, the other field contains the even lines. An interlaced image (such as the NTSC analog television standard) draws all the odd lines of an image first, then all the even lines. A video frame consists of all the odd and even lines that combine to create a complete image.
A flat-screen is a direct view video display with a screen that is flat instead of curved. Most direct view screens are slightly convex (slight curve inward). The advantage of a flat screen is that images on screen do not bend slightly or bow out at the sides and reflections are minimized. While a flat-screen picture is preferable to a curved screen picture, flat-screen televisions cost more to manufacture.
Flat-screens are often confused with thin video displays, such as plasma or DLP displays. CRT TVs and projection TVs can have flat screens.
A frame is one complete video image. By showing multiple frames in rapid succession, the illusion of motion is created. Movies display 24 frames a second, NTSC TV programming displays 30 frames a second.
In a sound wave, frequency measures the number of waves (the positive and negative crest and trough) sent out per second and can be used to measure the length of the individual waves (the wavelength). Frequency is measured in hertz (Hz).
Front Panel Lock
Front Panel lock is a feature available on some TVs. It allows you to disable the controls on the front of the TV so young children can’t change the TV’s settings.
Front Projection Video Display
A Front projection video display uses a large reflective screen and a separate projector mounted in front of the screen. Light from the projector shines onto the screen and images are reflected back to the viewer. Front projection is generally used with larger screen sizes. Because light coming from windows or lamps can interfere with the light traveling from the projector, projection displays should be watched in a dark room.
There are many types of projection displays, including LCD (liquid crystal display), DLP (digital light processing), and CRT (cathode ray tubes). Front projection displays take up less room than rear projection displays with the same screen size.
A/V, or Audio/Video, is a generic term used to describe products and services associated with audio and video. A/V is used to describe speakers, amplifiers, receivers, televisions, CDs, and computer sound and graphics cards.
Analog refers to a non-digital, continuous waveform signal. An analog signal is a continuous line with peaks and troughs rising above and sinking below a baseline, just like the waves on a lake. The smooth wave differs from a digital signal, which is composed of discrete bits, or chunks, of information. A digital signal can approximate a waveform, but does not create the same smooth, continuous flow representative of analog signals.
All sound waves are continuous analog waveforms. Digital audio signals are converted into an analog form in order for the amplifier and speaker to recreate sound. Sound waves cannot be created from digital data; to create a sound wave from a digital data, the data must be converted into analog. This is done with a digital-to-analog converter, or DAC.
An analog-to-digital converter is a device used to convert an analog (waveform) signal into a digital signal. Analog signals are constant, continuous waveforms.
Digital signals are made up of discrete (independent) ones and zeroes. The ones stand for an “on” state, and the zeroes for an “off” state. They do not form continuous waves like an analog signal; however, they are much easier to manipulate and they do not degrade with manipulation. For instance, a digital signal can be split it up, inverted and sent to multiple locations very easily. When an analog signal is manipulated in such a manner, the waveform is altered and noise is added, resulting in an impure signal.
The job of the analog-to-digital converter is to take the waveform (the analog signal) and split it up into the thousands of tiny “stairs” which simulate the sound wave. Once the signal is in the digital domain, it can be easily copied and manipulated with no degradation and with enhanced capabilities.
Movies are filmed in a widescreen format; when a movie is shown on TV, in order to fit the image in a TV’s 4-by-3 format, the sides of the movie are cut off and not shown. The anamorphic process compresses a “wide” video image horizontally (squeezes the sides in) to fit the traditional 4-by-3 TV standard, but the picture expands to full size when played over a wide video display (e.g., 16-by-9 format).
This is known as the “Letterbox” format. Letterboxing an image lets the viewer see the entire widescreen presentation of a movie as it was intended to be shown in a theater. In order to fit a “wide” image in a “narrow” television, the image is shown with black bars above and below it.
A movie can be distributed in a squeezed anamorphic format without black bars. On a 4-by-3 format television, this results in an image, which seems tall and pinched with actors looking too narrow and objects distorted. However, when played on a widescreen display, the picture is stretched out to its proper width with no bars.
An antenna is a metal rod or length of wire that sends or receives electromagnetic waves. Antennas are commonly used in audio/video to receive television signals and FM and AM radio signals.
An artifact is a visual anomaly or error in a video image. Artifacts are created when a compression system (particularly MPEG-2 compression) can’t keep up with fast action or complex scenes in a video image. Most artifacts take place in a single frame or a few frames and result in errors lasting a fraction of a second. Artifacts tend to appear as clumps of colored blocks or pixels that obscure part of an image (pixelization).
Aspect ratio is the relationship between the width and height of a video image. The aspect ratio for most televisions and computer monitors is 4:3 (four-by-three). The standard aspect ratio for digital HDTV is 16:9 (sixteen-by-nine), resulting in screens that are more rectangular. When a 4:3 image is displayed on a 16:9 screenblank areas appear on the left and right sides; sometimes these are referred to as black bars, pillars or side panels. Most widescreen TVs have a feature that can zoom or stretch a 4:3 image so that it fills up the 16:9.
The ATSC (Advanced Television Systems Committee) is an international, non-profit organization developing voluntary standards for digital television. The ATSC has approximately 140 member organizations representing the broadcast, broadcast equipment, motion picture, consumer electronics, computer, cable, satellite, and semiconductor industries.
ATSC formats are a series of 18 digital television formats, approved by the FCC for use by the television industry. The formats defined by the ATSC include both HDTV and SDTV formats to be used by off-air broadcasters.
The audio input is a connection jack (or plug) on an electronic component that receives electronic signals (with audio information) from a wire, or cable, sent by another component.
Calibration is adjusting video displays and audio equalizers to get the best quality and performance. Calibration uses standard tests with a known correctness level. The equipment is adjusted to match (as closely as possible) the known level.
Calibrating a television, for example, entails adjusting color, brightness, white level and other factors by using test screens. Audio equipment is calibrated using test tones of known frequencies.
CATV is cable television programming. Local cable companies transmit video and audio signals through coaxial cables to TVs, allowing a large number of channels with little distortion. With CATV, there is no need to use an antenna.
Chroma is the color information in a video signal. The chroma consists of saturation (amount of pure color) and hue (the color itself).
Chrominance is the color portion of a video signal. Video signals are made up of color portions (chrominance) and luminance (brightness, darkness and contrast). Chrominance tells the video display what colors to use and how much saturation (amount of pure color) to use, while luminance gives the colors depth and contrast by adjusting the darkness and brightness of the image.
CinemaScreen™ Floating Picture Screen
CimemaScreen is a type of video display with a borderless screen that gives images more vibrance and enables viewers to feel closer to the action.
A coaxial cable is a type of cable that carries both video and audio signals. Coaxial cable is used by cable and satellite companies. Coaxial cable plugs into RF input or output jacks. The connectors on the ends of coaxial cables are called F connectors. These connectors are either threaded like a screw or simply slide or push on. There are different types of coaxial cable; some is suited for cable-TV reception, but higher quality coaxial is needed for satellite signal transfer.
A comb filter separates the chrominance (color) and luminance (brightness) portions of a composite video signal. Comb filters are not used with S-Video (Y/C video) or component video connections (RB or Y, Pb, Pr), since those connections carry the chrominance and luminance separately. A filter is necessary for any composite video format, including laserdisc and television programming.
When using composite video, a comb filter is better than a notch filter.
Component video is a way of transferring video information without combining it into one signal. Component video sends the information in separate components: red, green and blue (RGB) or luminance, luminance minus blue, and luminance minus red (Y-Y/B-Y/R or Y-Pb-Pr). Component video offers a higher quality picture than composite or s-video.
Component video uses three coaxial video cables with RCA connectors (some components use BNC connectors) to transfer the three signal components.
Composite video transfers video information by combining color and brightness information into one signal. NTSC programming is a composite signal. Composite video uses a single video cable with an RCA connector.
Since composite video combines the chrominance and luminance signals together, a comb filter or a notch filter must divide the two signals back out before the video can be displayed. This process results in some distortion and picture degradation. A comb filter is better than a notch filter.
Compression is a technique that shrinks down data so it can travel faster or take up less space when stored. There are various compression methods.
The most common form of video compression is MPEG-2, used with digital television, DVD and direct broadcast satellite (DBS). A common form of audio compression is Dolby’s AC-3 method, used in Dolby Digital surround sound.
Big Screen TV
Big screen is a term used to refer to televisions or monitors with a diagonal (measured from corner to corner) screen size of 35 inches or more. Almost all projection televisions are considered big screen displays.
The smallest piece of digital data; bits are represented by either a one or a zero. There are eight bits in a byte. All digital devices use bits to transfer information.
Black level is the level of brightness or light present in the dark portions of a video image. When no light is emitted from a screen, the result is pure black. Better displays have a high black level (one with little brightness) in the dark areas. A poor video display may have a black level in which the “black” is actually a dark charcoal gray color. When a video display cannot achieve a good black level, the screen will lose some color saturation and appear slightly washed out. Images meant to be black will appear dark gray.
Brightness refers to the amount of light in a video image. Increasing brightness makes the image lighter. Decreasing brightness makes image darker.