telecommunications Telecommunication, often used in its plural form or abbreviated as telecom, is the transmission of information over a distance using electronic means, typically through cables, radio waves, or other communication technologies. These means of ...

, a digital multiplex hierarchy is a hierarchy consisting of an ordered repetition of

tandem Tandem, or in tandem, is an arrangement in which two or more animals, machines, or people are lined up one behind another, all facing in the same direction. ''Tandem'' can also be used more generally to refer to any group of persons or objects w ...

digital multiplexers that produce signals of successively higher

data Data ( , ) are a collection of discrete or continuous values that convey information, describing the quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted for ...

rates at each level of the hierarchy. Digital

multiplexing In telecommunications and computer networking, multiplexing (sometimes contracted to muxing) is a method by which multiple analog or digital signals are combined into one signal over a shared medium. The aim is to share a scarce resource� ...

hierarchies may be implemented in many different configurations depending on; (a) the number of channels desired, (b) the

signaling A signal is both the process and the result of transmission of data over some media accomplished by embedding some variation. Signals are important in multiple subject fields including signal processing, information theory and biology. ...

system A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its open system (systems theory), environment, is described by its boundaries, str ...

to be used, and (c) the

bit rate In telecommunications and computing, bit rate (bitrate or as a variable ''R'') is the number of bits that are conveyed or processed per unit of time. The bit rate is expressed in the unit bit per second (symbol: bit/s), often in conjunction ...

allowed by the

communications media Means of communication or media are used by people to communicate and exchange information with each other as an information sender and a receiver. General information Many different materials are used in communication. Maps, for example, s ...

. Some currently available digital multiplexers have been designated as Dl-, DS-, or M-series, all of which operate at

T-carrier The T-carrier is a member of the series of carrier systems developed by AT&T Bell Laboratories for digital transmission of multiplexed telephone calls. The first version, the Transmission System 1 (T1), was introduced in 1962 in the Bell Syst ...

rates. In the design of digital multiplex hierarchies, care must be exercised to ensure

interoperability Interoperability is a characteristic of a product or system to work with other products or systems. While the term was initially defined for information technology or systems engineering services to allow for information exchange, a broader de ...

of the multiplexers used in the hierarchy.

Digroup

Digroup is an abbreviation for

digital Digital usually refers to something using discrete digits, often binary digits. Businesses *Digital bank, a form of financial institution *Digital Equipment Corporation (DEC) or Digital, a computer company *Digital Research (DR or DRI), a software ...

group. In

telephony Telephony ( ) is the field of technology involving the development, application, and deployment of telecommunications services for the purpose of electronic transmission of voice, fax, or data, between distant parties. The history of telephony is ...

, a basic group in the digital multiplex hierarchy. In the North American and Japanese

digital hierarchies, each digroup supports 12 PCM voice channels or their equivalent in other services. The DS1 line rate (2 digroups plus overhead bits) is 1.544 Mbit/s, supporting 24 voice channels or their equivalent in other services. In the

E-carrier The E-carrier is a member of the series of carrier systems developed for digital transmission of many simultaneous telephone calls by time-division multiplexing. The European Conference of Postal and Telecommunications Administrations (CEPT) ori ...

European hierarchy, each digroup supports 15 PCM channels or their equivalent in other services. The DS1 line rate (2 digroups plus overhead bits) is 2.048 Mbit/s, supporting 30 voice channels or their equivalent in other services.

References

* Multiplexing {{telecom-stub

Digroup

See also

References