Page 236 - Electrical Engineering Dictionary
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dropout   equipment misoperation due to  DSB  See double sideband modulation.
                              an interruption, noise, or sag.
                                                                     DSI   See discrete sine transform.
                              dropout compensation   signal compen-
                              sation provided when a loss of information  DSL  See digital subscriber line.
                              from magnetic tape defects occurs during
                              VCR tape playback. Signal dropouts result  DSP  See digital signal processor.
                              from oxide or dust interfering with the tape-
                              head to tape contact when the VCR is in  DTE  See data terminal equipment.
                              the record or the playback operational mode.
                              A horizontal delay line stores the luminance  DTW  See dynamic time warping.
                              signal of the previous line that is used to re-
                              place the lost video information. The sig-  dual control  an adaptive control that per-
                              nal dropout is detected as a loss of the tape  forms two different functions at the same
                              playback. FM signal activates an electronic  time: one that applies probing signals to
                              switch. The switch substitutes the stored de-  learn more about the system dynamics and
                              lay line contents into the video path to com-  the other that tries to keep the output at a de-
                              pensate for the lost video from the tape play-  sired value.
                              back.
                                                                     dual functions  mathematical relationship
                              dropout current  the current at which a  betweentwosetsusedtorepresentasignal. If
                              magnetically-operated device will revert to  a signal s(t) can be represented by a complete
                                                                                         X
                              its de-energized position.             set {π n (t)}, i.e., s(t) =  a n π(t) n , there
                                                                                          n
                                                                     must exist a dual set {ˆπ n (t)} such that the
                              dropout voltage  the voltage level where
                                                                     expansion coefficients a n =< s(t), ˆπ n (t) >.
                              proper equipment operation is hindered.
                                                                     π n (t) and ˆπ n (t) are called dual functions. As
                                                                     a special case, if the set {π n (t)} is orthonor-
                              Drude material   a frequency-dependent
                                                                     mal, then it is its own dual.
                              dielectric whose complex permittivity is de-
                              scribed by an equation with two poles, one of
                                                                     dual in-line package (DIP)  a standard
                              them at w = 0. A collisional plasma is an ex-
                                                                     case for packaging integrated circuits. The
                              ample of such a material duration–bandwidth
                                                                     package terminates in two straight, paral-
                              reciprocity relation.
                                                                     lel rows of pins or lead wires. This stan-
                                                                     dard has been more recently substituted by
                              Drude media   See Drude material.
                                                                     surface-mount standards.  Compare with
                                                                     single in-line packaging.
                              drum memory     an old form of backing
                              memory. Similar to magnetic disks in opera-  dual mode filters  filters realized by us-
                              tion, but here the magnetic film is deposited  ing two resonances inside the same cavity,
                              on the surface of a drum, instead of a disk.  hence allowing saving of space, volume, and
                                                                     weight.
                              dry-type transformer  a transformer that
                              is cooled by circulating air or gas through or  dual phase-locked loop (DPLL)  pro-
                              around the transformer housing.        grammable, low-jitter, low-power, and high-
                                                                     performance devices. DPPLs are capable
                              DS-CDMA     direct sequence code division  of synthesizing two low-jitter clocks with
                              multiple access. See also direct sequence and  user-selected, industry-standard frequencies,
                              code division multiple access.         phased-locked to the system reference tim-



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