Understanding Data Transmission: Simplex, Half-Duplex, Full-Duplex & Wiring
Data Transmission Modes and Network Cabling
Simplex data transmission is performed in one direction, from a transmitting station to a receiving station. This typically corresponds to a terminal as the origin and a central computer as the destination, or a computer as the origin and a printer or display terminal as the destination.
Half-Duplex Transmission
Half-duplex transmission allows data to be sent in both directions, but not simultaneously. Devices connected in this mode act as both sender and receiver, but alternate between these functions. This communication method is increasingly common.
Full-Duplex Transmission
Full-duplex transmission allows data communication through a teleprocessing line in both directions simultaneously.
Network Wiring
Once you have the workstation, server, and network cards, you need to interconnect them. The type of cable used depends on several factors:
Popular network cabling types include twisted pair, coaxial cable, and fiber optics. Connections can also be made via radio or microwave.
Each cable type or method has its advantages and disadvantages. Some are prone to interference, while others cannot be used for security reasons. The speed and length of the run are also important factors when choosing a cable type.
Twisted Pair Cable
Twisted pair cable consists of two insulated copper wires twisted together. The pair is covered by an outer insulating layer. Its main advantages include:
- Well-studied technology
- No special skills required for installation
- Quick and easy installation
- Minimal signaling abroad
- Provides some immunity from interference, cross-modulation, and corrosion
Coaxial Cable
Coaxial cable consists of a copper conductor wire surrounded by a flat braided mesh that serves as ground. Between the wire and the mesh is a thick layer of insulation, and the whole is protected by an external covering.
The cable is available in two thicknesses: thick and thin.
Thick cable supports longer distances but is more expensive. Thin wire may be more practical for connecting nearby points.
The advantages of coaxial cable include:
- Supports broadband and baseband communications
- Useful for various signals, including voice, video, and data
- Well-studied technology
Fiber Optic Connection
Fiber optic connections are expensive but can transmit information at high speed and prevent line interference. Because the signal is transmitted by light, there are few possibilities of electrical or signal emission. The cable has two optical cores, one internal and one external, that refract light differently. The fiber is encased in a protective cable.
Fiber optic connections offer the following advantages:
- High-speed transmission
- No electrical or magnetic signals emitted, resulting in security
- Immunity to interference and cross-modulation
- Greater economy than coaxial cable in some facilities
- Supports longer distances
Wireless Communication
Microwave Communication
Information is transmitted through the air via electromagnetic waves. This has the advantage of not requiring a physical link, and the bandwidth is virtually unlimited. However, a visual link is needed between the transmitter and receiver points. Due to the Earth’s topography, the maximum separation is around 50 kilometers, unless intermediate repeaters are installed to receive the signal from the transmitter and send it to the recipient.
Satellite Communication
This uses an artificial geostationary satellite as a repeater for a microwave link, allowing great distances to be reached. However, atmospheric changes can affect transmission.