电信专业英英词典D-6
Direct Inward Dialing (DID)
DID is PBX-to-central office trunks that allow incoming calls to a PBX to ring specific stations without attendant assistance. DID greatly reduces the number of required console attendants, compared with systems in which all calls must be extended by console attendants.
Direct Outward Dialing (DOD)
DOD is PBX-to-central office trunks that allow outgoing calls to be placed directly by PBX stations.
Dispersion
In dispersive 1 media, dispersion are complex signals are distorted because the various frequency components 2 which make up the signal have different propagation characteristics and paths. Due to the finite conductivity of copper 3, wire or cable media for guided wave transmission is fundamentally dispersive. Dispersion limits the upper bit rate that a medium can support by distorting the signal waveforms to the extent that transitions from one information state to another cannot be reliably detected by receiving equipment, (e.g., logical l logical 0 value changes).
DLCI
data link connection identifier
DOD
direct outward dialing
DQDS
DS"N" Digital Signal Hierarchy 5
A time division multiplexed hierarchy of standard digital signals used in telecommunications systems. DS1 level in the hierarchy corresponds to a 1.544 Mbps TDM signal which comprises 24 DS0 signals. DS0 refers to individual digital signals at channel rates of 64 kbps. Four DS1 signals digitally multiplexed produce a DS2 level signal, containing 96 DS0 channels, and requires a transmission medium that supports 6.312 Mbps. A DS3 level signal results from the digital multiplexing of 7 DS2 signals, supports 672 DS0 signals and requires a 44.736 Mbps transmission medium. Finally a DS4 level signal supports 6 DS3 level signals, 4032 DS0 signals and requires a 274.176 Mbps transmission medium. The DS hierarchy accounts for non synchronism in the multiplexing plan, hence the term "asynchronous digital hierarchy" and the use of overhead bits. Note that bit rates at higher levels are not integer multiples of 64 kbps.
DSP
digital signal processor
DSS/BLF
direct station selection/busy lamp field
DSS
digital subscriber service
- In many atomic fluorescence applications a non-dispersive optical system may be used. 在许多原子荧光法的应用中，可以采用非分散的光学系统。
- The wave are of course dispersive. 当然这种波是弥散的。
- the components of a machine 机器部件
- Our chemistry teacher often reduces a compound to its components in lab. 在实验室中化学老师常把化合物分解为各种成分。
- The students are asked to prove the purity of copper.要求学生们检验铜的纯度。
- Copper is a good medium for the conduction of heat and electricity.铜是热和电的良导体。
- The people's Republic of China does not recognize dual nationality for any Chinese national.中华人民共和国不承认中国公民具有双重国籍。
- He has dual role as composer and conductor.他兼作曲家及指挥的双重身分。