Copyright Goodheart-Willcox Co., Inc. 53 Chapter 2 Network Media—Copper-Core Cable Simplex, Full-Duplex, and Half-Duplex Communication Communication between two electronic devices can occur in one of three modes: simplex, full-duplex, and half-duplex, as shown in Figure 2-5. Simplex refers to com- munication that occurs in one direction only. An example of simplex communication is the transmission that occurs between a television station and a television. Full- duplex communication is bidirectional communication that occurs between two de- vices simultaneously. An example of full-duplex communication is communication via telephone. Half-duplex communication is also bidirectional communication however, it can only occur in one direction at a time. Half-duplex communication is used with walkie-talkies. Most LANs use half-duplex communication. Ethernet is an excellent example. In an Ethernet network, only one computer or node can success- fully transmit data over the network cable at a time. If two computers transmit data at the same time, a collision occurs and the data is destroyed. Most modern communication is done with full-duplex communication. Sim- plex and half-duplex systems are very rare in modern computer networks, but were once common implementations. Electronic Terms Networks that incorporate copper cable have limits to the type of cable, length, num- ber of segments, and the number of nodes that can be connected. Th ese limits are based on certain electrical characteristics. As you read about the copper cable types and the IEEE 802 classifi cations, you will learn what these limitations are. However, there are several basic electronics terms you must fi rst master to fully understand these limitations. Direct Current and Alternating Current Th e fl ow of electrical energy is described as either direct current (DC) or alternating current (AC). Th e term current describes the fl ow of electrons, which is the actual Home TV station Simplex = One-way transmission Half-duplex = Two-way transmission— each device taking a turn to communicate Full-duplex = Two-way transmission— each device communicating simultaneously Antenna Walkie-talkies Telephones Figure 2-5 Examples of simplex, half-duplex, and full-duplex communication. Goodheart-Willcox Publisher