Time-assignment speech interpolation
Encyclopedia
In telecommunication
, a time-assignment speech interpolation (TASI) was an analog technique used on certain long transmission
links to increase voice-transmission capacity.
TASI worked by switching additional users onto any channel
temporarily idled because an original user
has stopped speaking. When the original user resumes speaking, that user would, in turn, be switched to any channel that happened to be idle. The speech detector function is called voice activity detection
.
One of the issues with using this type of technology was that that users listening on an idled channel can sometimes hear the conversation that has been switched onto it. Generally the sound heard was of very low volume and individual words are not distinguishable. See also crosstalk for a similar phenomenon in telecommunications.
TASI was invented by Bell Labs
in the 1960s to increase the capacity of transatlantic telephone cable
s. It was one of their first applications requiring electronic switching
of voice circuits.
Later Digital Circuit Multiplication Equipment
included TASI as a feature, not as distinct hardware.
Telecommunication
Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...
, a time-assignment speech interpolation (TASI) was an analog technique used on certain long transmission
Transmission (telecommunications)
Transmission, in telecommunications, is the process of sending, propagating and receiving an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired, optical fiber or wireless...
links to increase voice-transmission capacity.
TASI worked by switching additional users onto any channel
Channel (communications)
In telecommunications and computer networking, a communication channel, or channel, refers either to a physical transmission medium such as a wire, or to a logical connection over a multiplexed medium such as a radio channel...
temporarily idled because an original user
User (telecommunications)
In telecommunications, a user is a person, organization, or other entity that employs the services provided by a telecommunication system, or by an information processing system, for transfer of information....
has stopped speaking. When the original user resumes speaking, that user would, in turn, be switched to any channel that happened to be idle. The speech detector function is called voice activity detection
Voice activity detection
Voice activity detection , also known as speech activity detection or speech detection, is a technique used in speech processing in which the presence or absence of human speech is detected.. The main uses of VAD are in speech coding and speech recognition...
.
One of the issues with using this type of technology was that that users listening on an idled channel can sometimes hear the conversation that has been switched onto it. Generally the sound heard was of very low volume and individual words are not distinguishable. See also crosstalk for a similar phenomenon in telecommunications.
TASI was invented by Bell Labs
Bell Labs
Bell Laboratories is the research and development subsidiary of the French-owned Alcatel-Lucent and previously of the American Telephone & Telegraph Company , half-owned through its Western Electric manufacturing subsidiary.Bell Laboratories operates its...
in the 1960s to increase the capacity of transatlantic telephone cable
Transatlantic telephone cable
A transatlantic telecommunications cable is a submarine communications cable running under the Atlantic Ocean. All modern cables use fibre optic technology....
s. It was one of their first applications requiring electronic switching
Electronic switching system
In telecommunications, an electronic switching system is:* A telephone exchange based on the principles of time-division multiplexing of digitized analog signals. An electronic switching system digitizes analog signals from subscriber loops, and interconnects them by assigning the digitized...
of voice circuits.
Later Digital Circuit Multiplication Equipment
Digital Circuit Multiplication Equipment
Digital Circuit Multiplication Equipment was a type of voice compression equipment that is installed at either end of a long-distance link . The main characteristics of DCME are defined in ITU-T recommendation G.763...
included TASI as a feature, not as distinct hardware.