Main Page | See live article | Alphabetical index In communications, duplex means "two-way" when referring to communications channels. A simplex channel is a one-way channel. A half-duplex channel is one that can carry information in both directions, but cannot carry it in both directions at the same time. A full-duplex channel is a channel which can carry information in both directions at once. These terms apply also to early PC sound cards. Most are now full-duplex. Where channel access methods are used for dividing forward and reverse communication channels on the same physical communications medium, they are known as duplexing methods, such as: Time division duplex (TDD) is the application of Time division multiple access to separate outward and return signals Frequency division duplex (FDD) is the application of Frequency division multiple access to separate outward and return signals A duplex home is one in which there are two separate residences, usually side-by-side, but sometimes on two different floors. The former often looks like two houses put together, sharing a wall; the latter usually appears as a townhouse, but with two different entrances. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.