Digital Circuit Multiplication Equipment
Encyclopedia
Digital Circuit Multiplication Equipment (DCME) was a type of voice compression
equipment that is installed at either end of a long-distance link (typically communications satellite
or submarine communications cable
). The main characteristics of DCME are defined in ITU-T recommendation G.763. DCME consists of a voice interpolation
stage, which is a form of statistical multiplexor applied to voiceband signals, and a low rate encoding stage which exploits correlation between successive voiceband samples on an individual input channel to reduce the transmitted bitrate from that required by PCM
of equivalent quality.
Under heavy loading conditions (for example when a large number of channels show continuous activity due to voiceband data or Group III facsimile signals) the voice interpolation may not be able to operate within a satisfactory quality range - discontinuous signals such as speech being affected by competitive clipping of the initial part of the activity. To combat this DCME may incorporate Dynamic Load Control on a range of input channels. Dynamic load control is a form of back busying to the telephone switch.
The DCME's functionality, from the point of view of the telephone switch attached to its local interface, is standardised by ITU-T
Recommendation Q.50.
Voice compression
Voice compression may mean different things:*Speech encoding refers to compression for transmission or storage, possibly to an unintelligible state, with decompression used prior to playback....
equipment that is installed at either end of a long-distance link (typically communications satellite
Communications satellite
A communications satellite is an artificial satellite stationed in space for the purpose of telecommunications...
or submarine communications cable
Submarine communications cable
A submarine communications cable is a cable laid on the sea bed between land-based stations to carry telecommunication signals across stretches of ocean....
). The main characteristics of DCME are defined in ITU-T recommendation G.763. DCME consists of a voice interpolation
Time-assignment speech interpolation
In telecommunication, a time-assignment speech interpolation was an analog technique used on certain long transmission links to increase voice-transmission capacity....
stage, which is a form of statistical multiplexor applied to voiceband signals, and a low rate encoding stage which exploits correlation between successive voiceband samples on an individual input channel to reduce the transmitted bitrate from that required by PCM
Pulse-code modulation
Pulse-code modulation is a method used to digitally represent sampled analog signals. It is the standard form for digital audio in computers and various Blu-ray, Compact Disc and DVD formats, as well as other uses such as digital telephone systems...
of equivalent quality.
Under heavy loading conditions (for example when a large number of channels show continuous activity due to voiceband data or Group III facsimile signals) the voice interpolation may not be able to operate within a satisfactory quality range - discontinuous signals such as speech being affected by competitive clipping of the initial part of the activity. To combat this DCME may incorporate Dynamic Load Control on a range of input channels. Dynamic load control is a form of back busying to the telephone switch.
The DCME's functionality, from the point of view of the telephone switch attached to its local interface, is standardised by ITU-T
ITU-T
The ITU Telecommunication Standardization Sector is one of the three sectors of the International Telecommunication Union ; it coordinates standards for telecommunications....
Recommendation Q.50.