Return channel

Return channel

In communications systems that use star topologies, the return channel (also reverse channel, back 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 where this is true include ADSL (where the "A" stands for "asymmetric"), cable modems, cellular Internet access facilities (e.g. 3G) and satellite internet access.

The return channel need not use the same medium as the main channel. For example, some "hybrid" Internet access services use a one-way cable television system for the forward channel and a dial-up modem and telephone line for the return channel.

Even when the return and forward channels use the same medium, their differencesoften dictate the use of very different data modulation and coding techniques. For example, in a star radio network,only the central hub transmits on the forward link, so multiple access contention isa consideration only on the return link.

The "forward/return" terminology is also used for spacecraft command and telemetry links. Because the return link carries telemetry, it is often orders of magnitude faster than the forward link that transmits onlya few predefined spacecraft commands.

"Return" and "forward" links are distinct from, and should not be confused with, uplinks and downlinks in satellite communication systems. For example, satellite Internet access withconventional bent pipe spacecraft transponders requires a total of two uplinks and two downlinks. One uplink and downlink pair are used for the forward link from the central ground hub through the satellite to the user termanal, and another uplink/downlink pair areused for the return link from the user terminal to the central hub.

ee also

*Backhaul (telecommunications)
*Broadband
*Satellite Internet


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • DVB return channel — Dieser Artikel wurde wegen inhaltlicher Mängel auf der Qualitätssicherungsseite der Redaktion Film und Fernsehen unter Angabe von Verbesserungsvorschlägen eingetragen. Beteilige Dich an der Verbesserung dieses Artikels und entferne diesen… …   Deutsch Wikipedia

  • Astra Return Channel System — Astra Return Channel System,   ARCS …   Universal-Lexikon

  • Return — may refer to:* Return (architecture), the receding edge of a flat face * Return (finance), the financial term for the profit or loss derived from an investment * Tax return, a form submitted to taxation authorities * Carriage return, a key on an… …   Wikipedia

  • Channel (communications) — Old telephone wires are a challenging communications channel for modern digital communications. In telecommunications and computer networking, a communication channel, or channel, refers either to a physical transmission medium such as a wire, or …   Wikipedia

  • Channel 5 (UK) programming — Channel 5 airs a wide variety of programming that coveres various genres and themes. Launched in 1997, the channel has always been seen to have less distinctive programming than their other terrestrial rivals at the BBC, ITV and Channel 4. The… …   Wikipedia

  • Channel 5 (UK) — Channel 5 Channel 5 logo Launched 30 March 1997 (1997 03 30) Owned by Northern Shell …   Wikipedia

  • Return of the Living Dead (film series) — Return of the Living Dead is a series of films that was produced between 1985 2005. The series came about as a dispute between John Russo and George A. Romero over how to handle sequels to their 1968 film, Night of the Living Dead . The two… …   Wikipedia

  • Return to Halloweentown — DVD cover Distributed by Disney Channel …   Wikipedia

  • Channel Airways — IATA CW ICAO Callsign Founded 1946 Cease …   Wikipedia

  • Channel coordination — (or supply chain coordination) aims at improving supply chain performance by aligning the plans and the objectives of individual enterprises. It usually focuses on inventory management and ordering decisions in distributed inter company settings …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”