Distribution frame
Encyclopedia
For example, the Main Distribution Frame
Main distribution frame
In telephony, a main distribution frame is a signal distribution frame for connecting equipment to cables and subscriber carrier equipment . The MDF is a termination point within the local telephone exchange where exchange equipment and terminations of local loops are connected by jumper wires...
(MDF) located at a telephone central office
Telephone exchange
In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls...
terminates the cables leading to subscribers on the one hand, and cables leading to active equipment (such as DSLAMs and telephone switches) on the other. Service is provided to a subscriber by manually wiring a twisted pair
Twisted pair
Twisted pair cabling is a type of wiring in which two conductors are twisted together for the purposes of canceling out electromagnetic interference from external sources; for instance, electromagnetic radiation from unshielded twisted pair cables, and crosstalk between neighboring pairs...
(called a jumper wire) between the telephone line
Telephone line
A telephone line or telephone circuit is a single-user circuit on a telephone communication system...
and the relevant DSL or POTS
Plain old telephone service
Plain old telephone service is the voice-grade telephone service that remains the basic form of residential and small business service connection to the telephone network in many parts of the world....
line circuit.
In broadcast engineering
Broadcast engineering
Broadcast engineering is the field of electrical engineering, and now to some extent computer engineering and information technology, which deals with radio and television broadcasting...
, a distribution frame is a location within an apparatus room through which all signals (audio
Sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...
, video
Video
Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...
, or data
Data
The term data refers to qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which...
) pass, with the ability to arbitrarily route and connect sources and destinations between studio
Studio
A studio is an artist's or worker's workroom, or the catchall term for an artist and his or her employees who work within that studio. This can be for the purpose of architecture, painting, pottery , sculpture, scrapbooking, photography, graphic design, filmmaking, animation, radio or television...
s and other internal and external points. Connections can either be solder
Solder
Solder is a fusible metal alloy used to join together metal workpieces and having a melting point below that of the workpiece.Soft solder is what is most often thought of when solder or soldering are mentioned and it typically has a melting range of . It is commonly used in electronics and...
ed, or made using terminal blocks. Because the frame may carry live broadcast signals, it may be considered part of the airchain
Airchain
In broadcast engineering for radio or television, the airchain or transmission chain is the path or route an audio or video signal takes on its way through a radio station or television station.The airchain begins with cameras, microphones, CD players, turntables, telephone hybrids, video tape...
.
Types
Distribution frames for specific types of signals often have specific acronyms:- ADF - audioSoundSound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...
distribution frame - DDF - digitalDigitalA digital system is a data technology that uses discrete values. By contrast, non-digital systems use a continuous range of values to represent information...
distribution frame - VDF - videoVideoVideo is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...
distribution frame - ODF or OFDF - optical fiberOptical fiberAn optical fiber is a flexible, transparent fiber made of a pure glass not much wider than a human hair. It functions as a waveguide, or "light pipe", to transmit light between the two ends of the fiber. The field of applied science and engineering concerned with the design and application of...
distribution frame
Modernization
Distribution frames may grow to extremely large sizes. In major installations, audio distribution frames can have as many as 10,000 incoming and outgoing separate copper wires (balanced audioBalanced audio
Balanced audio is a method of interconnecting audio equipment using impedance-balanced lines. This type of connection is very important in sound recording and production because it allows for the use of long cables while reducing susceptibility to external noise.Balanced connections use...
signals require two wires plus earth ground for each signal). Telephone signals do not use a separate earth ground wire, but some urban exchanges
Telephone exchange
In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls...
have about 250,000 wires on their MDF
Main distribution frame
In telephony, a main distribution frame is a signal distribution frame for connecting equipment to cables and subscriber carrier equipment . The MDF is a termination point within the local telephone exchange where exchange equipment and terminations of local loops are connected by jumper wires...
. Installing and rewiring these jumpers is a labour-intensive task, leading to attempts in the industry to devise so-called active distribution frames or Automated Main Distribution Frame
Automated Main Distribution Frame
Automated Main Distribution Frame , , a technology to provide connectivity between subscriber - and office equipment lines in a telephone exchange main distribution frame .At the beginning of the 21st century the connections...
s. The principal issues which stand in the way of their widespread adoption are cost and reliability.
Newer digital
Digital
A digital system is a data technology that uses discrete values. By contrast, non-digital systems use a continuous range of values to represent information...
mixing console
Mixing console
In professional audio, a mixing console, or audio mixer, also called a sound board, mixing desk, or mixer is an electronic device for combining , routing, and changing the level, timbre and/or dynamics of audio signals. A mixer can mix analog or digital signals, depending on the type of mixer...
s can act as control point
Control point
Control point may refer to:*Control point *Control point *Control point *Control point *Port of entry*Control point...
s for a distribution frame or router, which can handle audio from multiple studios (even for multiple co-located radio
Radio station
Radio broadcasting is a one-way wireless transmission over radio waves intended to reach a wide audience. Stations can be linked in radio networks to broadcast a common radio format, either in broadcast syndication or simulcast or both...
or tv
Television station
A television station is a business, organisation or other such as an amateur television operator that transmits content over terrestrial television. A television transmission can be by analog television signals or, more recently, by digital television. Broadcast television systems standards are...
stations) at the same time. Multiple smaller frames, such as one for each studio, can be linked together with fibre-optics (which also helps eliminate ground loops
Ground loop (electricity)
In an electrical system, a ground loop usually refers to a current, almost always unwanted, in a conductor connecting two points that are supposed to be at the same potential, often ground, but are actually at different potentials. Ground loops created by improperly designed or improperly installed...
), or with gigabit Ethernet
Gigabit Ethernet
Gigabit Ethernet is a term describing various technologies for transmitting Ethernet frames at a rate of a gigabit per second , as defined by the IEEE 802.3-2008 standard. It came into use beginning in 1999, gradually supplanting Fast Ethernet in wired local networks where it performed...
. This has the advantage of not having to route dozens of feeds through wall
Wall
A wall is a usually solid structure that defines and sometimes protects an area. Most commonly, a wall delineates a building and supports its superstructure, separates space in buildings into rooms, or protects or delineates a space in the open air...
s (and sometimes floor
Floor
A floor is the walking surface of a room or vehicle. Floors vary from simple dirt in a cave to many-layered surfaces using modern technology...
s and ceiling
Ceiling
A ceiling is an overhead interior surface that covers the upper limit of a room. It is generally not a structural element, but a finished surface concealing the underside of the floor or roof structure above....
s) to a single point.
See also
- Main distribution frameMain distribution frameIn telephony, a main distribution frame is a signal distribution frame for connecting equipment to cables and subscriber carrier equipment . The MDF is a termination point within the local telephone exchange where exchange equipment and terminations of local loops are connected by jumper wires...
- Intermediate distribution frameIntermediate distribution frameIntermediate distribution frame : In a central office or customer premises, a frame that cross-connects the user cable media to individual user line circuits and may serve as a distribution point for multipair cables from the main distribution frame or combined distribution frame to individual...
- Wiring closetWiring closetA wiring closet is a small room commonly found in institutional buildings, such as schools and offices, where electrical connections are made. While they are used for many purposes, their most common use is for computer networking...
- Patch panelPatch panelA patch panel or patch bay is a panel, typically rackmounted, that houses cable connections. One typically shorter patch cable will plug into the front side, whereas the back holds the connection of a much longer and more permanent cable...
- SpliceboxSpliceboxA splice box is a housing in which fiber optic cables begin or end. Fiber optics are fanned out in splice boxes that are situated at the end of fiber optic transmission paths...