- d-: see deci- (d-).
- da-: see deka- (da-).
- DA: see Distribution Amplifier
- Acronym: Digital To Analog Converter
- DIY: A circuit that takes digital input and converts it into analog output.
- Acronym: Digital Automatic Music
- Audio: Refers to compact discs containing songs in both MP3 and standard CD audio format.
- Acronym: Digital Advanced Mobile Phone Service
- Telephony: A term used for digital cellular radio in North America.
- Acronym: Disc At Once
- Audio: A method of recording to CD in which the disc is written all at once without interruption and without the recording laser turning off. It is generally considered the best method for recording a CD. DAO also allows you to record separate tracks onto CD without the 2 second gap between each track (compare to TAO).
- Dark Current or Dark Noise
- Digital Video: The charge accumulated by pixels while not exposed to light. Normally, this charge is reduced or eliminated prior to capturing a picture.
- Darlington Pair
- Electronics: An amplifier consisting of two bipolar junction transistors with their collectors connected together and the emitter of one connected to the base of the other. A darlington pair circuit is characterized by both high current gain and high input impedance.
- Acronym: Digital Audio Tape
- Audio: An digital recording media format designed to allow music to be digitally stored onto magnetic cassette tape.
- dB: see Decibel.
- Acronym: Digital Broadcast System
- Satellite: A digitally-transmitted direct satellite television broadcast.
- Computers: A 25-pin D-shell connector. This is the standard connector used for serial connections.
- Computers: A 9-pin D-shell connector. This is a smaller version of the DB-25 connector and is also used for serial connections.
- Acronym: Direct Current
- DIY, Electronics: An electrical current that flows in one direction only, as opposed to alternating current (AC), in which the current flow alternates direction in a regular manner.
- Acronym: Digital Compact Cassette
- Audio: A digital recording media format developed by Philips and Matsushita in the 1990's. It has been replaced in the home market by CD-R and CD-RW.
- Acronym: Digital Cordless Standard
- Telephony: A cellular telephone system used in Europe.
- Telephony: A low-power variant of GSM with a 1.8 GHz carrier wave, used in Europe.
- Telephony: A proposed usage for GSM with a 1.9 MHz carrier wave, for PCS applications.
- deci- (d-)
- Measurement: SI / Metric unit of decimal measurement, equal to 10-1 or 0.1.
- Decibel (dB)
- Measurement: One tenth of a bel, a unit used to compare the ratio of two quantities (such as sound pressure, power, or intensity), or to express the ratio of one such quantity to an appropriate reference. The chart below shows decibel ratings along with common examples of sounds of that level.
||Threshold of hearing
Hearing testing booth
||Isolated broadcast studio
Quiet rural area at night
||Quiet suburban area at night
||Quiet suburban area in daytime
Conversation in restaurant
Typical urban area
Electric sewing machine
On sidewalk by passing automobiles
||Busy urban street
On sidewalk by passing heavy truck or bus
Roar of crowd at sporting event
Convertible ride on freeway
Jet takeoff (300 Meters)
On platform by passing subway train
Snowmobile drvrs seat
||Subway train screech
- Video: A device that is connected between a video source (satellite receiver or cable TV line) and the television, enabling the user to decode scrambled signals. The decoder is built into DTH satellite antennas.
- Audio: A decoder converts an MP3 file into audio or another format (such as WAV) before playing as audio.
- Computers: The process of restoring the contents of a compressed file.
- Acronym: Digital European Cordless Telephone
- Telephony: A digital cordless telephone standard used in Europe that incorporates some of the features of the cellular telephone systems. DECT telephones use picocells, and calls can be handed off from one cell to the next.
- Deep Discharge
- Batteries: Discharging a battery to a specific cut-off voltage at a low current rate. Discharge cut-off voltage is generally considered to be 0.5 volts.
- Computers: The connector type for VGA monitor connections.
- deka- (da-)
- Measurement: SI / Metric unit of decimal measurement, equal to 10.
- Communications: The process of recovering a signal from a modulated carrier so that it has substantially the same characteristics as the original signal.
- Depth of Field
- Digital Video: The distance between the nearest and farthest points that appear in acceptably sharp focus in a photograph (digital or analog). Depth of field varies with lens aperture, focal length, and camera-to-subject distance.
- Depth Penetration
- Metal Detectors: The greatest measure of a metal detector's ability to transmit an electromagnetic field into the soil matrix and produce a target signal.
- Detection Pattern
- Metal Detectors: The densest or strongest region of the search coil's electromagnetic field where detection occurs. It is balloon-shaped and changes in size in direct proportion to the target surface area.
- Metal Detectors: Adjusting the audio threshold into the null or less-sensitive tuning zone. It is also a method of narrowing a target's signal width manually for precise pinpointing. This is accomplished by returning to audio threshold over the target response area.
- Plug 'n Power: Appliances that can be plugged into modules that control the appliance when an X-10 signal is received from a controller.
- Weather: condensation in the form of small water drops that forms on grass and other small objects near the ground when the temperature has fallen to the dew point, generally during the nighttime hours.
- Dew Point
- Weather: The temperature to which air must be cooled at a constant pressure to become saturated.
- Electronics: A bidirectional thyristor that has two terminals and uses a symmetrical switching mode.
- DIY, Electronics: The insulating material between the conductive plates of a capacitor.
- Dielectric Constant
- Electronics: The property of a material that determines how much electrostatic energy can be stored per a given volume when a given voltage is applied.
- Dielectric Strength
- Electronics: The maximum voltage an insulating material can withstand without breaking down.
- Metal Detectors: An indention left by previous hunters.
- A system that uses bits to represent variables and store information, as compared to analog, which uses physical change to represent variables.
- Audio: Digital recordings represent sounds that have been converted into groups of electronic bits, or zeroes and ones, and stored on a magnetic medium; those groups of bits are then read electronically. In the case of a CD player, the bits are read by a laser beam. Conversely, with analog technology, the grooves on a vinyl record are read physically by a needle. Because digital data are represented numerically, they can be copied repeatedly and each succeeding generation of copies is identical to the original. See Analog.
- Digital Advanced Mobile Telephone Service: see D-AMPS.
- Digital Modulation: see Modulation, Digital.
- Digital Video: The adjustable aperture that controls the amount of light passing into the camera. The diaphragm may be in front of, within or behind the lens.
- Digital Audio
- Audio: An audio signal from a digital source (DTV broadcast, DVD, CD Player, Satellite Receiver) that is carried by either a digital coax cable or an optical cable.
- Digital Coax
- Audio: A coaxial cable specifically designed to carry a digital audio signal.
- Digital Video
- Video: A video signal in a digital format (DTV, SDTV or HDTV), that is normally carried on component video cables for the highest video quality, although other outputs (such as for analog video) may be available.
- Digital Zoom: see Zoom, Digital.
- Electronics, Computers: The process of converting analog information into a digital format.
- Plug 'n Power: A type of module used for incandescent lighting appliances only. They respond to the commands Dim and Bright as well as ON and OFF.
- DIN Connector
- Analog: Deutsches Insitut für Normung eV (German)
- Electronics: A round, multi-pin connector that conforms to the standards set by Deutsches Insitut für Normung eV, a German organization responsible for setting standards. See the DIN Connector FAQ.
- DIY, Electronics: A polarized semiconductor component (having a negative and positive electrode) that is designed to conduct electricity in only one direction.
- Diode Logic: see DL.
- Diode, Schottky
- Electronics: A high-speed diode that has very little junction capacitance. Also known as a Hot-carrier Diode or Surface-barrier Diode.
- Diode, Surface-barrier: see Diode, Schottky.
- Diode-Transistor Logic: see DTL.
- Diode, Zener
- Electronics: A semiconductor diode in which the reverse breakdown voltage current causes the diode to develop a constant voltage. Used as a clamp for voltage regulation.
- Diopter Correction
- Digital Video: An adjustment on the viewfinder of a camera, allowing the user to adjust the viewfinder for near-sighted or far-sighted vision so that he or she does not need to wear glasses to use the camera.
- Acronym: Dual In-line Package
- Electronics: An integrated circuit package that has two rows of connecting pins.
- Audio, Video, Communications: A dual-rod antenna, usually found as a back-of-set or on-set antenna.
- Video, Communications: A device used to combine two different signals (such as from a broadcast antenna and from a satellite system or cable television service) onto a single cable so that they can be split back into the individual signals for connection at the video equipment.
- Direct Current: see DC.
- Operating in a particular direction.
- Audio, Video, Communications: Refers to antennas that are designed to receive signals along a line forward from the antenna. Also called Unidirectional. Compare to Bidirectional and Omnidirectional.
- Direct Vision
- Digital Video: Refers to cameras that use an optical viewfinder.
- Discharge Curve
- Batteries: A plot of voltage against time, at a given current drain and temperature. Generally speaking, primary batteries have sloping discharge curves and secondary batteries have flat curves.
- Discharge Rate
- Batteries: The current at which a battery is discharged.
- Communications: An antenna that has the horizontal elements connected to the shield and the cone connected to the coax cable's center conductor, so that the actual configuration is an upside-down half-bow-tie
- Metal Detectors: Adjustable circuitry which ignores or nulls audio responses from a specific conductivity range allowing positive responses to be heard from metals higher in conductivity above the discriminate control setting. Designed primarily to eliminate audio response from unwanted metals.
- Discriminator, Mineral Free
- Metal Detectors: A detector that can reject or ignore trash metals while simultaneously eliminating or balancing the effect of mineralized ground.
- Discriminator, Motion
- Metal Detectors: A detector type that requires search coil motion to activate its simultaneous ground balance and discriminate functions. See also Mineral-Free Discriminator and VLF/TR.
- Satellite: The flat part of the satellite antenna that reflects the signal to the LNB.
- Dish Network®
- Satellite: A DTH (Direct-To-Home) satellite system service provider. The "Dish" in "Dish Network" is an acronym for "Digital Sky Highway".
- Dispatch Calls
- Communications: Standard mobile-to-mobile or mobile-to-base calls that do not use the Public Switch Telephone Network (PSTN).
- Audio: Unwanted audio signals that alter an input signal. Distortion is caused by a variety of factors.
- Digital Video: A defect in an digital image, such as barreling and pincushioning, caused by a flaw in the lens.
- Measurement: Critical rate of rise of on-state current.
- Acronym: Diode Logic
- Electronics: A logic gate that uses diodes to perform AND and OR logic functions.
- Acronym: Digital Millennium Copyright Act
- An act signed in 1998 for the purpose of updating the copyright laws of the United States.
- Acronym: Digital MultiMeter
- DIY: A multimeter with a digital display.
- Acronym: Distant Network Service
- Satellite: A service that allows the user to use a DTH (Direct-To-Home) satellite system in either a recreational vehicle or a commercial truck.
- Dolby® Digital
- Audio: A digital coding method using AC-3® coding to convey one or more audio channels, generally at a bit rate of 384 kbps.
- Dolby® Stereo
- Audio: An audio coding method used to convey surround sound over three speakers. Called Dolby® Surround in the consumer market.
- Dolby® Surround: see Dolby Stereo®.
- Dolby® Pro Logic®
- Audio: A type of improved decoder used to decode Dolby Surround® content, using four speakers.
- Audio: A dome-shaped cone.
- Doppler Shift
- GPS: A change in the wavelength (frequency) of energy in the form of waves.
- Double Blip
- Metal Detectors: A signal characteristic common to elongated ferrous targets such as nails or coins lying close to the surface detected in the All Metal no-motion mode.
- Double D: see Scan, Wide.
- Satellite: Data being sent from a satellite down to an earth station.
- Computers: 1) To transfer data from a device to a computer using a direct connection.
- Acronym: Double Pole Double Throw
- Electronics: A six-terminal switch or relay that can handle two separate circuits. Essentially, two SPDT switches or relays combined into a single component.
- Acronym: Dots Per Inch
- Computers, Digital Video: A measurement value used to describe the resolution of a display screen or the output resolution of a printer.
- Acronym: Digital Print Order Format
- Digital Video: A format that allows you to embed printing information on a memory card.
- Acronym: Double Pole Single Throw
- Electronics: A four-terminal switch or relay that can open or close two separate circuits. Essentially, two SPST switches or relays combined into a single component.
- The element in a field-effect transistor that is comparable to the collector in a bipolar transistor.
- Acronym: Dynamic Random Access Memory
- Computers: Temporary memory that is lost when the power is turned off.
- DRAM Buffer
- Acronym: Dynamic Random Access Memory Buffer
- Digital Video: Fixed memory used for image processing before the image is stored. Cameras with a burst mode have much larger DRAM buffers.
- Metal Detectors: A loss of threshold tuning stability caused by temperature change, battery condition, mineral content, and/or detector design.
- Audio: see Speaker Driver.
- Computers: The program that allows a piece of hardware to work with a particular computer or operating system.
- Weather: A very light, misting precipitation.
- Drizzle, Freezing
- Weather: drizzle, falling as a liquid, but freezing on impact with the colder ground or other exposed surfaces. It is reported as "fzdz" in an observation and on the metar.
- Acronym: Digital Rights Management
- Audio: The term for the various methods of tracking the sale and distribution of digital music.
- Dry Bulb Thermometer: see Thermometer, Dry Bulb.
- Dry Cell: see Cell, Dry.
- D-Shell Connector
- Electronics, Computers: A connector type primarily used in computers. The most common types are the DA-15, DB-25, DC-37, DD-50, DE-9, and DEH-15 connectors. The "D" refers to the shape of the connector, the following letter or letters refer to the connector size, and the number refers to the number of pins.
- Acronym: Direct Stream Digital
- Audio: The recording technology used in SACD. DSD promises better sonic performance as the encoded bitstream somewhat resembles the analog characteristics of the original analog signal.
||Super Audio CDs (SACD)
||44.1 kHz / 16-bit
|Samples per second
- Acronym: Digital Subscriber Line
- Internet: A technology that allows high-speed Internet connections on standard telephone lines (POTS). The primary types of DSL are ADSL (Asymmetric Digital Subscriber Line) and SDSL (Symmetric Digital Subscriber Line).
- Acronym: Digital Signal Processing or Digital Signal Processor
- Audio: The method of manipulating analog information that has been converted into a digital form, or a component that is used for this purpose.
- Acronym: Direct To Home
- Satellite: Refers to home-based satellite systems.
- Acronym: Diode-Transistor Logic
- Electronics: A logic gate that uses diodes to perform AND and OR logic functions and then uses a transistor as an amplifier on the resulting signal.
- Acronym: Dual Tone Multi-Frequency
- Telephony: The signal encoding used for dialed numbers, using two tones out of a group of eight. DTMF is the method used by touch-tone telephones, as opposed to the original pulse method, used by rotary telephones.
- DTS Digital Surround
- Acronym: Digital Theater Systems
- Audio: A digital coding method used to convey one or more audio channels.
- Acronym: Digital TeleVision
- Video: A television standard that consists of High-definition Digital Television (HDTV) and Standard-definition Digital Television (SDTV).
- Communications: A scanner reception method that uses a circuit with two stages and two intermediate frequencies to extract the data signal from the carrier.
- Dual In-line Package: see DIP.
- Acronym: Digital Video
- Digital Photography: Used to describe digital camcorders and digital camcorder tapes.
- Acronym: Currently, DVD is not considered to be an acronym. Previously, it was an acronym for "Digital Versatile Disc"; and originally, it was an acronym for "Digital Video Disc".
- Video: A video format that uses optical discs to store audio and video information. The parameters for DVD video are given below:
||720 x 480
||720 x 576
|Video Data Rate:
||4~8 Mbps CBR or VBR (Constant/Variable Bit Rate)
||Stereo, 48 kHz and 192~384 kbps MPEG audio
- Audio, Video: A format for high-resolution audio and multi-channel music. It is based on the DVD format, but contains only audio information.
- Measurement: Critical rate of rise of off-state voltage.
- Acronym: Distant X (transmitter or transmission)
- Communications: Used to describe a long-distance transmission, generally from a foreign country. "DXing" is the hobby of seeking out and listening to these transmissions.
- Dye Sub
- Acronym: Thermal Dye Sublimation
- Computers: A printing process where the ink is thermally transferred to printing media. Dye sub is generally more expensive than other methods; however, it provides extremely high quality. Additional cost is incurred because dye sub printers require special paper.
- Dynamic Range
- Digital Video: The measurement (in bits) of the accuracy of an image in color or gray level. A higher dynamic range results in finer gradations being preserved.
- Measurement: Cgs unit for force; equal to (g * cm * sec-2).