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 RadioShack Consumer Electronics Glossary: R

RA (.ra)
Acronym: Real Audio
Audio: A Real Media audio file extension, indicating a file readable by the RealOne™ Media Player.
Radio-Frequency Wireless Remote
Plug 'n Power: A remote controller that sends a signal to a base transceiver which is connected to the electrical system. In turn an X-10 signal is sent to modules with the same address.
Measurement: A line that extends from the center of a circle or sphere to the edge of the circle or sphere.
Weather: Precipitation in the form of liquid water droplets greater than 0.5 mm. If widely scattered, the drop size may be smaller. The intensity of rain is based on rate of fall. "Very light" means that the scattered drops do not completely wet a surface. "Light" means it is greater than a trace and up to 0.10 inch an hour. "Moderate" means the rate of fall is between 0.11 to 0.30 inch per hour. "Heavy" means over 0.30 inch per hour.
Weather: The amount of precipitation of any type, primarily rain. It is usually the amount that is measured by a rain gauge.
Rain, Freezing
Weather: Rain that falls as liquid and freezes upon impact to form a coating of glaze on the colder ground or other exposed surfaces.
Rain Gauge
Weather: An instrument used to measure the amount of rain that has fallen. Measurement is done in hundredths of inches (0.01").
Acronym: Random Access Memory
Computers: The most common type of computer memory, which is used by the CPU to store software, programs, and data currently being used. RAM is usually volatile memory, meaning that when the computer is turned off, crashes, or loses power, the contents of the memory are lost. A large amount of RAM usually offers faster manipulation or faster background processing.
Random Access Memory: see RAM.
Digital Video: Usually a separate viewing device independent of the lens and often mounted above and to the right or left of the lens. Also called the Viewfinder.
Acronym: CCD Raw Format
Digital Video: The uninterpolated data collected directly from the image sensor before processing.
Acronym: Red, Blue, Yellow
Video: Used to describe the three color components of a component video signal.
Acronym: Remote Controlled or Radio Controlled
Consumer Electronics: Refers to a device which has a wireless controller, such as an RC vehicle.
Audio: The resistance of the speaker driver's voice coil (less than the rated impedance).
Reactance (X)
DIY, Electronics: The opposition to the passage of AC (alternating current) in electronic components, caused by either capacitance (Capacitive Reactance, XC) or inductance (Inductive Reactance, XI).
Reactance, Capacitive (XC)
Electronics: The opposition to the passage of AC (alternating current) in electronic components caused by capacitance and determined by the equation below, where f is the AC frequency in hertz and c is the capacitance in farads.
XC = 1 / (2 pi f c)
Reactance, Inductive (XI)
Electronics: The opposition to the passage of AC (alternating current) in electronic components caused by inductance and determined by the equation below, where f is the AC frequency in hertz and I is the inductance in henries.
XI = 2 pi f I
Real Media
Digital Audio, Digital Video, Internet: The company which produces the RealOne™ Media Player.
Audio, Communications: A device that picks up radio signals from a transmitter and converts it into an audio signal.
Electronics, Plug 'n Power: A device (module) that receives commands from a transmitter (controller) and passes the signal to the appliance that is attached to it.
Receiver, Audio/Video
Audio, Video: A device that acts as a central hub for an audio system, providing multiple inputs for various audio components (including inputs for video audio such as VCR's or DVD players) and a single set of outputs to speakers.
Receiver, GPS
GPS, Satellite: A piece of equipment that is used by the civilians and the military to pick up satellite signals that contain data, in order to locate position.
Receiver, Satellite
Satellite: A device which is connected to and receives the signal from the LNB via cable and converts it to a standard Audio/Video signal. DTH receivers have built-in decoders; older C-Band receivers may require a separate decoder.
Recharge Life
Batteries: The number of times that a rechargeable battery can be effectively recharged.
Recording Industry Association of America: see RIAA.
Electronics: The process of converting an AC voltage to a pulsating DC voltage.
Electronics: A diode circuit that converts an AC voltage to a pulsating DC voltage.
Rectifier, Bridge
Electronics: A diode circuit that uses four diodes to provide full wave rectification.
Rectifier, Center-tapped
Electronics: A diode circuit that uses a center-tapped transformer and two diodes to provide full wave rectification.
Rectifier, Full-wave
Electronics: A diode circuit that uses the full AC wave in both the positive and negative half cycles.
Rectifier, Half-wave
Electronics: A diode circuit that only uses either the negative or the positive alternation of each input AC cycle to convert an AC voltage to a pulsating DC voltage.
Electronics: Converting an AC voltage to a pulsating DC voltage.
Recycle time
Digital Audio: The time it takes to process and store a captured image.
Digital Audio: An effect caused by an electronic flash reflecting off of the human eye and making it look red.
Red-eye Reduction
Digital Audio: A feature on many cameras which reduces the occurence of red-eye by firing a preliminary flash to close the iris of the eye before firing the main flash to take the picture.
Reed Relay: see Relay, Reed.
Audio, Communications: The effect which occurs when RF waves bounce off of hills, buildings, moving cars, the atmosphere, and basically almost anything in the RF transmission environment, causing the transmission to "bend" around corners, reaching areas which would be otherwise be blocked.
Refresh Rate
Digital Audio: The time it takes the camera to capture the image after you press the shutter release.
Computers, Electronics: To restore the device to its original factory settings.
Regulated Power Supply: see Power Supply, Regulated.
Electronics: A device that contains a coil and a set of contacts which close when the coil is activated.
Relay, Reed
Electronics: A relay in which the contacts are two thin magnetic strips within a glass envelope.
Relay, Socketed
Electronics: A relay with blade-type leads, which are designed to fit into a specific relay socket.
Relay, Ultraminiature
Electronics: An IC (integrated circuit) that functions as a relay.
Repertory Dialing
Telephony: A feature that allows you to store and recall telephone numbers using memory built into the telephone. Also called Memory Dialing or Speed Dialing.
Electronics, Communications: To return a device (such as a scanner) to the original factory settings. This usually clears all information stored in the device's memory.
DIY, Electronics: The property of a conductor, expressed in ohms, indicating how the conductor resists passage of electrical current.
Resistance Thermometer: see Thermometer, Resistance
Resistance, Forward
Electronics: The resistance of a forward-biased junction in a semiconductor when there is current through the p-n junction.
Resistive Load: see Load, Resistive.
Electronics: The ability of a material to resist passage of electrical current, expressed in either the ohm-cm (for volume resistivity), or the ohm (for surface resistivity).
DIY, Electronics: A component made of a material that opposes the flow of electrical current.
Resistor, Carbon-film
Electronics: A resistor constructed by depositing a thin carbon film on a ceramic form.
Resistor, Carbon
Electronics: A resistor constructed of carbon granules mixing into a binding material.
Resistor, Metal-film
Electronics: A resistor in which a film of metal oxide or alloy is deposited on an insulating substrate.
Resistor, Metal-oxide
Electronics: A metal-film resistor in which an oxide of metal (such as tin) is deposited as a film onto the substrate.
Resistor Network
Electronics: A component which consists of interconnected resistors.
Resistor, Terminating
Computers, Networking: A device used to fill unused 50-ohm connections on T-connectors.
Video: A device used to fill unused 75-ohm outputs on signal amplifiers, distribution amplifiers or splitters; unused outputs which are not terminated can cause "ghosting" and signal loss.
Resistor-Transistor Logic: see RTL.
Resistor, Variable
Electronics: A resistor in which the resistance can be changed by turning a shaft. See also Potentiometer and Rheostat.
Resistor, Wirewound
Electronics: A resistor in which the resistive element is a length of high resistance wire or ribbon usually nichrome wound onto an insulating form.
Digital Audio: The quality of an audio signal's recording, measured as the bit rate (in kbps, or kilobits per second).
Digital Video: Used to describe the quality of an image by indicating either the number of pixels (horizontally by vertically) or the number of megapixels. The higher the resolution, the more pixels are used in the image, providing more image information and a clearer picture. Resolution formats include QVGA (320 x 240), VGA (640 x 480), SVGA (800 x 600), XGA (1024 x 768) and UXGA (1600 x 1200).
Resolution, Digital: see Resolution, Interpolated.
Resolution, Interpolated
Digital Video: A number based on adding pixels to the image based on existing pixels. While interpolation increases the number of pixels, it does not increase the amount of image information and can cause pixelation.
Resolution, Optical
Digital Video: An absolute number indicating the number of pixels that the camera's image sensor can physically record. Compared to interpolated resolution, optical resolution is a clearer indication of the camera's capabilities.
Electronics: The condition of a circuit in which the net reactance is zero and the current flow is maximized. Also called Resonant Frequency.
Resonance, Free Air
Resonance, System
Resonant Frequency: see Resonance.
Response, Narrow
Metal Detectors: A target that produces an audio response so short that pinpointing is almost not needed.
Response, Negative
Metal Detectors: A reduction in the audible tone.
Response, Neutral
Metal Detectors: No change in the audible tone.
Response, Phase
Metal Detectors: The length of time between eddy current generation sustained on a metal's surface and the resultant secondary electromagnetic field effect on the search coil's receive winding. Related to target conductivity.
Response, Positive
Metal Detectors: An increase in tone.
Response, Quick
Metal Detectors: A short time period between metal sensing and peak audio/ visual indicator indication usually associated with all frequency ranges of TR detectors.
Response, Wide
Metal Detectors: A target that produces an audio signal over an area wider than the search coil diameter.
Metal Detectors: An indication of target non-acceptance by a null in threshold or broken sound while operating in a discriminate mode.
Reverse Current: see Current, Reverse.
Acronym: Radio Frequency
Communications: A radio signal generated by a transmitter, or a radio signal which can be picked up by a receiver.
Acronym: Radio Frequency Interference
Consumer Electronics, Communications: A problem which occurs when a receiver picks up RF signals that interfere with the signals that it is intended to receive. RFI can affect nearly any electronic audio/video device.
RF Modulator
Acronym: Radio Frequency Modulator
Audio, Video: A device which converts composite audio/video (audio left, audio right and video) into a single 75-ohm signal, such as for connecting to a television with only a coax "F" input.
RF-Two Box
Acronym: Radio-Frequency Two Box
Metal Detectors: A radio frequency detector with 2 separate coils. This type of detector is capable of detecting large, deep objects while naturally ignoring small targets such as nails and individual coins.
RG-# cable
Acronym: Radio Guide
Cables: The military designation (no longer used by the military) for coax cable.
RG-11 (/U)
Acronym: Radio Guide 11 (/Universal)
Cables: A high-quality 75-ohm coax cable used to minimize signal loss, such as due to low signal or a long cable run.
RG-58 (/U)
Acronym: Radio Guide 58 (/Universal)
Cables: A 50-ohm coax cable used for CB, Ham, shortwave and scanner antenna hookups.
RG-59 (/U)
Acronym: Radio Guide 59 (/Universal)
Cables: A lower-grade 75-ohm coax cable which can be used in place of RG-6 for some applications.
RG-6 (/U)
Acronym: Radio Guide 6 (/Universal)
Cables: A 75-ohm coax cable used for video connections.
Acronym: Radio Guide 6 Quad-Shielded
Cables: A 75-ohm coax cable with Quad-Shielding used for video connections (providing higher protection against radio interference and loss).
RG-62 (/U)
Acronym: Radio Guide 62 (/Universal)
Cables: A 93-ohm coax cable.
RG-8 (/U)
Acronym: Radio Guide 8 (/Universal)
Cables: A 50-ohm coax cable used for CB, Ham, shortwave and scanner antenna hookups.
Acronym: Radio Guide 8M
Cables: A 50-ohm coax cable with a smaller diameter than RG-8, but a larger diameter than RG-8/X. It is used for CB, Ham, shortwave and scanner antenna hookups.
Acronym: Radio Guide 8X
Cables: A mini 50-ohm coax cable which can be used for CB, Ham, shortwave and scanner antenna hookups.
RG-9 (/U)
Acronym: Radio Guide 9 (/Universal)
Cables: A 51-ohm coax cable.
Acronym: Red, Green, Blue
Video: The components of a standard color signal.
Digital Video: The color system used in most digital cameras in which the image is separated by capturing the red, green, and blue light separately and then are re-combined to create a full color image.
Electronics: A variable resistor with two terminals, which is used to control current.
Acronym: Recording Industry Association of America
Audio: The association formed by the recording companies in the United States to promote the recording industry and to defend its legal rights.
Computers, Networking: A network topology in which the computers are connected as illustrated below. See also Bus, Star, Mesh, Tree.
Ring Topology
Audio: The process of taking CD audio and recording it to a computer in any file format (also called digital audio extraction). When the transfer is from CD to MP3, the process encompasses both ripping and encoding.
Acronym: Registered Jack
Cables, Telephony: A pref
Acronym: Registered Jack 11
Cables, Telephony: The most common telephone jack . While it can have six conductors, it is usually installed with only four (a red and green pair, and a black and white pair). The red and green pair usually carries the voice or data signal for a single telephone line.The black and white pair may be used for other low-voltage signals.
Acronym: Registered Jack 14
Cables, Telephony: A telephone jack similar to the RJ-11, except that the four wires (a red and green pair, and a black and yellow pair) are used for two telephone lines. Typically, the red and green pair carries the voice or data signal for one telephone line, and the yellow and black wire carry the signal for the second telephone line.
Acronym: Registered Jack 45
Cables, Telephony: A single-line, 8-conductor jack for digital transmission over ordinary telephone wire, either untwisted or twisted.
RM (.rm)
Acronym: Real Media
Computers, Internet: A Real Media file extension, indicating a file readable by the RealOne™ Media Player.
Acronym: Root-Mean-Square
Audio: A rating indicating the continuous power output (for amplifiers) or input (for speakers).
DIY, Electronics: A mathematical method for defining the effective voltage or current of an AC wave. The RMS of an AC waveform is equal to the square root of the result of squaring the waveform function and averaging it over time.
Telephony: A mobile station which operates in the cellular system other than the one from which the service is subscribed (the home system).
Telephony: Using a mobile station in a cellular system other than the home system. Roaming can be area (over a state or group of metropolitan areas), national (within a single country) or international/world-wide.
Root-Mean-Square: see RMS.
Telephony: Telephones which are dialed by turning a dial to produce a pulsed signal. This telephone type has been replaced by touch-tone telephones, which are dialed by pressing keys to produce DTMF tones. Technically, only rotary telephones are "dialed", but the term has become part of common vocabulary.
Telephony: A device used with a mast-mounted directional or bidirectional antenna which allows you to change the direction of the antenna.
GPS: A group of waypoints entered into the GPS receiver in the sequence you desire to navigate them. Waypoints are points on a journey or route where a traveler can stop or change course.
Acronym: Rotations Per Minute
DIY, Measurement: An indication of how fast a device is turning.
Acronym: Recommended Standard 232
Computers: The EIA/TIA standard which defines the mechanical and electrical interface for serial communications over DB-25, DB-9, or RJ-45 style connectors. There are three subcategories based on the connector type: RS-232C (DB-25), EIA/TIA 574 (DB-9), and RS-232D (RJ-45).
Acronym: Rural Service Area
Telephony: One of the 428 FCC-designated rural markets across the United States. There are two cellular carriers licensed in each RSA. See also MSA, CGSA.
Measurement: Slope resistance (on-state).
Acronym: Resistor-Transistor Logic
Electronics: A logic gate that uses transistors to combine multiple input signals and amplify and invert the resulting signal.
Rural Statistical Area: see RSA.
Communications: shorthand for Receive or Receiving.
Video: The color difference between the red component and the luma -- Cr' in the YCbCr color space and Pr' in the YPbPr color space.

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