Editing Backward channel

{{no footnotes|date=March 2013}}

In a [[data transmission circuit]] a '''backward channel''' is the channel that passes data in a direction opposite to that of its associated forward [[Communication channel|channel]].  The backward channel is usually used for transmission of request, supervisory, [[acknowledgement (data networks)|acknowledgement]], or [[error]]-control signals. The direction of flow of these signals is opposite to that in which [[user information]] is being transferred.  The backward-channel [[Bandwidth (computing)|bandwidth]] is usually less than that of the primary channel, that is, the forward ([[user information]]) channel.  For example, [[Asymmetric Digital Subscriber Line|ADSL]]'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]], 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]] that controls the direction of transmission in the [[primary channel]].

== See also ==
* [[Return channel]]

==References==
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*[[Federal Standard 1037C]]
*[[MIL-STD-188]]
{{refend}}

[[Category:Data transmission]]


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