Definition
- In a network, a communication channel is a physical path the transmission signals travel.
- It is the path information travels from computer to computer.
- How do the computers in a network “connect” to each other.
The 5 communication channels
- twisted-pair cables
- coaxial cables
- fiber optic cables
- terrestrial stations
- communication satellites
Twisted pair cables
- Signals are transmitted using pairs of independently insulated wires that have been physically twisted together
- Used by older telephone networks
- Network cables use an RJ-45 jack for four pairs of twisted-pair cables.
Coaxial cables
- Core of the wire is copper
- High frequency signals can be carried on a single cable – used for video transmission
- Used when twisted pair cabling is not adequate to carry the required amount of data.
Fibre Optic Cables
- Digital signals are sent as light pulses which are translated back into electrical signals
- Composed of fine glass strands
- The Centre core is composed of: Fine glass strand surrounded by glass cladding and protective layer
- Glass cladding reflects light back into the core, guiding the light along the wire
- Thousands of transmissions can be carried on a single strand
- Can transmit signals faster than twisted pair and coaxial cables
Terrestrial Stations
- Information is sent via microwaves from ground based transmitting and receiving stations
- Text, sound, and graphics are converted into microwave pulses and transmitted
- Microwave stations (a.k.a. repeater stations) must be placed every 50 kilometres to receive, amplify, and then pass the signal along
- Transfer information at much higher speeds than cabling
Communication Satellites
- Orbiting around earth
- Avoids cost of cabling and repeater stations
- Minimum of three satellites are needed to provide world-wide communication
- Transfer information at much higher speeds than cabling
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