In a
data transmission circuit
In telecommunication, a data transmission circuit is the transmission media and the intervening equipment used for the data transfer between data terminal equipment ( DTEs).
A data transmission circuit includes any required signal conversion eq ...
a backward channel is the channel that passes data in a direction opposite to that of its associated forward
channel. The backward channel is usually used for transmission of request, supervisory,
acknowledgement, or
error
An error (from the Latin ''error'', meaning "wandering") is an action which is inaccurate or incorrect. In some usages, an error is synonymous with a mistake. The etymology derives from the Latin term 'errare', meaning 'to stray'.
In statistics ...
-control signals. The direction of flow of these signals is opposite to that in which
user information
User information is information transferred across the functional interface between a source user and a telecommunications system for delivery to a destination user.
In telecommunications systems, user information includes user overhead informat ...
is being transferred. The backward-channel
bandwidth
Bandwidth commonly refers to:
* Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range
* Bandwidth (computing), the rate of data transfer, bit rate or thr ...
is usually less than that of the primary channel, that is, the forward (
user information
User information is information transferred across the functional interface between a source user and a telecommunications system for delivery to a destination user.
In telecommunications systems, user information includes user overhead informat ...
) channel. For example,
ADSL
Asymmetric digital subscriber line (ADSL) is a type of digital subscriber line (DSL) technology, a data communications technology that enables faster data transmission over copper telephone lines than a conventional voiceband modem can provide. ...
's upstream channel, considered a backward channel for some types of analysis, typically has a bandwidth less than one-fourth of the downstream channel.
In
data transmission
Data transmission and data reception or, more broadly, data communication or digital communications is the transfer and reception of data in the form of a digital bitstream or a digitized analog signal transmitted over a point-to-point o ...
, it is a secondary channel in which the direction of transmission is constrained to be opposite to that of the primary, ''i.e.'', the forward (user-information) channel. The direction of transmission in the backward channel is restricted by the control
interchange circuit In telecommunication, an interchange circuit is a circuit that facilitates the exchange of data and signaling information between data terminal equipment In telecommunication, the term terminal equipment has the following meanings:
* Communicatio ...
that controls the direction of transmission in the
primary channel.
See also
*
Return channel In communications systems, the return channel (also reverse channel or return link) is the transmission link from a user terminal to the central hub. Return links are often, but not always, slower than the corresponding forward links. Examples whe ...
References
*
Federal Standard 1037C
Federal Standard 1037C, titled Telecommunications: Glossary of Telecommunication Terms, is a United States Federal Standard issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, a ...
*
MIL-STD-188
MIL-STD-188 is a series of U.S. military standards relating to telecommunications.
Purpose
Faced with "past technical deficiencies in telecommunications systems and equipment and software…that were traced to basic inadequacies in the applicat ...
Data transmission
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