Re-Equalization
Re-EQ. A specification for THX® home theatre systems in which there is a gradual rolloff in the high frequency range of the front channels, starting from 2 kHz. Soundtracks mixed for the large theatrical environment were perceived to be too bright when reproduced in the much smaller confines of the home, so Re-EQ is applied to restore the original tonal balance of the sound. The concept of Re-EQ was first introduced in surround sound components in 1981 with the Fosgate-Tate II Decoder.
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Re-Recording
Also known as dubbing or mixdown. The process of creating the final soundtrack mix for the print master from the essential elements — music, sound effects, Foley and dialogue.
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Receiver
Receives all 18 ATSC Table III formats and produces a usable picture. See Grand Alliance, DTV (Digital TeleVision), HDTV (High Definition TeleVision) and ATSC.
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Reference Level
The Sound Pressure Level to which a sound system is adjusted when pink noise at reference electrical level is played over one channel at a time. It is generally measured with C weighting and the SLOW characteristic of a sound level meter. See SPL.
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Reflected Sound
Sound arriving at the listening location after bouncing off one or more of the surrounding surfaces. Because sound waves lose energy according to the distance traveled and number of reflections encountered, reflected sound wave are always of less intensity than similar waves arriving directly from the source. The sum total of all reflected waves determine the room’s reverberation time and acoustical character.l
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Reflections
With video signals, reflections can be caused by energy that is not absorbed by the load (or a termination), and is reflected back and possibly combined with the original signal. Reflection signals can occur when the impedance does not match (because of wrong termination or mixing of cable impedance). Some of the undesirable results of reflection include: Y/C delays, color smearing, ringing on luminance (but not on color), ghosts, etc.
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Refraction
1) In audio the bending of sound waves traveling through layered media with different sound velocities. 2) In video the bending or unbending of the direction of light rays.
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Relay
A device that acts like a switch and is controlled by a current. The relay switch contacts then control another circuit, or pass a signal, etc. Most types of relays are solid state or electromagnetic.
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Release Print
The actual film played in the theatre. A release print consists of reels approximately 20 minutes long which are played consecutively without interruption either by alternating between two projectors, or by splicing the individual reels together into one large reel called a platter. Prints are played at 24 frames per second and prints are recorded at 16 frames per foot.
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Remote Control
A device for controlling the function a machine at a distance. May be wired or wireless.
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Remote Types
TV sets either include a Basic, Standard, Unified, Universal, or Learning remote. There are also a few sets that include combination Universal/Learning remotes.
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Resilient
Free from rigid contact, such as a spring-mounted floating floor. Resiliency helps prevent the transfer of noise and vibration from one structure to another.
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Resolution
The density of lines or dots for a given area that make up an image. Resolution determines the detail and quality in the image. A measure of the ability of a camera or video system to reproduce detail. A measure of the amount of detail that can be seen in an image. Often incorrectly expressed as a number of pixels (picture elements); more correctly it is the bandwidth. We say that a sharp, clear picture has high resolution. See Resolution (Horizontal) and Resolution (Vertical).
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Resolution
The fineness of detail that can be distinguished in an image, as on a video display. 1) Horizontal. The amount of detail in a horizontal direction in a video image. It is expressed as the number of distinct vertical lines, alternately black and white, that can be seen in the width of the picture. This information is usually derived from observation of the vertical wedge of the test pattern. Horizontal resolution depends on the high-frequency amplitude and phase response of the pick-up equipment, as well as the transmission medium and the monitor itself. 2) Vertical. The amount of resolvable detail in a vertical direction in a video image. It is expressed as the number of distinct horizontal lines, alternately black and white, that can be seen in a test pattern. Vertical resolution is primarily fixed by the number of horizontal scanning lines in a frame. 3) In audio, the ability of a system to resolve very small details within complex sounds. Resolution enhances reproduction of the quiet intervals between sounds, and allows the listener to distinguish between, and to follow the melodic lines of the individual voices or instruments comprising a large performing group.
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Resonance
The sympathetic vibration of an object having mass and stiffness (or air column) at a specific frequency when it is excited into motion by a sound wave of similar frequency in the immediate vicinity. The vibration of a body or air cavity at its natural resonant frequency, having been set into motion by a nearby vibrating source.
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Resonant Frequency Dip
The degradation of transmission loss of a barrier at a specific frequency due to inner resonance. The exact frequency at which this phenomenon occurs is a function of the mass and stiffness of the barrier.
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Response, Frequency
The accuracy with which a given device reproduces the audible frequency range.
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Response, Transient
The response of a device to rapid fluctuations in sound pressure or voltage.
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Retrace
During the scanning of a picture onto a screen, scan lines are produced from left to right. Before scanning the next line, the electron beam must get back to the left side of the screen. This is called "Retrace." The beam must be turned off (blanked) during retrace time. See Horizontal Blanking and Vertical Blanking.
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Retrace Time
The minimum time required to move the scanning beam from the right side to the left side of the CRT screen.
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Retro Reflective Screen Surface
In a Retro Reflective screen the light is reflected back in the direction of the source. An example of a Retro reflective element is the glass beaded screen that is used for slide projection. The projector is centered on the screen from a long distance behind the audience. The dispersion of light comes off the screen filling the head level area of the audience, reflecting back in the direction of the projector. This works well for projectors with a lot of light and a long throw distance, although glass beads do funny things in light dispersion that are not kind to picture detail. Since most video projectors don’t fit in the long throw distance, high light output category, they are best displayed on Angular Reflective screens. See Angular Reflective Screens.
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Reverberant Field
The area in a room, in which the multitude of decaying reflections has created a reverberant and diffuse condition.
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Reverberation
1) The persistence of sound in a room after the actual source has stopped. This is a result of the multiple reflections of sound waves throughout the room arriving at the ear so closely spaced that they are indistinguishable from one another and are heard as a gradual decay of sound. The reflection of sound in large acoustical environments. The size of the listening space and reflectivity of the walls determine the degree of reverb perceived by the listener. In a theatre, reverb can affect the intelligibility of dialogue and the spaciousness of the surround sound. 2) (Artificial) The simulation of the natural reverberation effect by a mechanical device using springs or plates electronic processing effects to simulate vibrational medium.
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Reverberation Time
The time it takes for sounds in a room to decay to one millionth of their original level (60 dB of decay). The reverberation time (RT) of a room varies with frequency and is a function of the room volume as well as the total number of absorption units in the room.
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RF
See Radio Frequency.
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RF Adapter
A device that allows video and audio signals from a VTR or computer to be shown on a standard TV receiver. This device produces comparatively poor resolution and picture quality. Also called RF Converter.
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RF Control
A medium of remote control from which signals are sent to the controlled equipment via data pulses modulated on an RF carrier signal.
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RGB
Red, Green, Blue. The chrominance information in a video signal. The basic primary components of the color television system. They are also the primary colors of light, not to be confused with cyan, magenta, and yellow, the primary pigments. Also called the "additive color process."
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RGB (Inputs/Outputs)
RGB is a special set of inputs that separate R (red), G (green), and B (blue) colors for much improved picture quality. These type of inputs are normally found on Front Projector sets. By bypassing the set’s internal composite and S-Video circuitry and connecting directly to the circuits driving the electron guns, RGB inputs normally deliver a sharper and crisper picture clarity reaching data-grade quality.
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RGB Monitor
A color monitor that uses color "guns" for red, green and blue to produce a high-quality picture.
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RGB Sync
RGBS. Red, blue and green, the chrominance information in a video signal, with the addition of a sync channel.
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RGB Video
A form of color video signal (red, green, blue) distinctly different from the composite color video used in standard television sets. RGB can be displayed only on a color monitor that has a separate electron gun for each of these primary colors. Some color television sets use only one gun. RGB monitors are noted for their crisp, bright colors and high resolution. RGB Video can be four different ways: RGsB (sync is on the green signal), RGBS (sync is separate from the colors), RGBHV (sync is separate from the colors and the horizontal and vertical are separate signals) and RsGsBs (sync on red, green and blue).
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Ringing
High frequency patterns usually associated with over-peaking of a video amplifier.
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RISC Technology
A Reduced Instruction Set Computer (RISC) is based on a microprocessor technology that simplifies information processing through a reduced set of instruction formats. It is known for its fast execution of CPU instructions.
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Rise Time
The time required for a signal to go from 10 percent to 90 percent of its maximum amplitude level.
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Rolling
Continuous vertical movement of a video picture, due to loss of vertical synchronization.
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Rolloff
A gradual attenuation in the level of a signal above or below a specified frequency.
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ROM
Read Only Memory. Permanent memory that can only be loaded once, normally by a manufacturer. Contents may not be altered or removed. See PROM, EPROM and EEPROM.
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Root Mean Square
RMS. The value of a waveform equal to the value of a continuous signal (i.e. direct current) with the same power output as the initial wave. The RMS value of a sine wave is found by squaring all values of the waveform in question and then taking the square root of the average result. This value turns out to always be .707 times the peak value of the wave. The RMS value of a complex wave must take into account all the various frequency components and is more complicated to calculate.
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RPTV
Rear Projection Television. See Rear Screen Projection.
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RS-170A
EIA technical standard NTSC color TV. A video standard that ensures proper synchronization of video signals and components.
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RS-232
An Electronic Industries Association (EIA) serial digital interface standard specifying the characteristics of the communication path between two devices using D-type connectors. This standard is used for relatively short range communications and does not specify balanced control lines. A serial control standard with a set the number of conductors, data rate, word length and type of connector to be used. Also specifies component connection standards with regard to computer interface. Also called RS-232-C, which is the third version of the RS-232 standard, which is functionally identical to the CCITT V.24 standard.
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RS-330
EIA technical standard which provides details for industrial closed circuit television (CCTV).
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RS-422
An EIA serial digital interface standard which specifies the electrical characteristics of balanced (differential) voltage digital interface circuits. This standard is usable over longer distances than RS-232. This signal governs the asynchronous transmission of computer data at speeds of up to 920,000 bits per second. It is also used as the serial port standard for Macintosh computers.
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RTA
See Real Time Analyzer.
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Rumble
Low-frequency vibration.
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