From the course: Electrical Systems: Communications and Data

Copper-based communications systems

From the course: Electrical Systems: Communications and Data

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Copper-based communications systems

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- [Narrator] Just like the telegraph, modern communication systems are based on their use of copper conductors using pulses of electricity to transmit information. Copper cables are installed and connected to end user equipment such as telephones, computers, copy machines and printers, cameras, speakers and a whole bunch of other user equipment. Cables must be installed by qualified individuals with a good understanding of how the systems work and who know how to avoid interruptions due to poor craftsmanship. Copper is used in cables because of its low resistance to electricity and its ability to carry the signals great distances with little disturbance. Here's how it works. First, electricity, direct current specifically, is modulated on copper wires to make a frequency. This frequency can be turned back into sounds by the use of a magnetic speaker like that found in a telephone handset. Usually a pair of copper wires makes up this pathway between the two users. Small diameter copper wires are twisted together, often referred to as twisted pair. Twisting a pair of copper wires for the purposes of communications discourages the bleeding of other signals from other close conductors bleeding onto them and creating interference. That's also known as crosstalk. But not all copper cable is a twisted pair. Some cables are built from the inside out. The name for these cables is coaxial or coax cables. Coax cables are commonly used for transmitting video signals for television, cable TV and closed-circuit TV. The signal's carried throughout the center conductor, also known as the core. The core is protected and insulated by a foam type of compound, also known as the dielectric. Outside of that is another copper used to protect the signal inside and it's called a shield. It can be like a braid of copper strands or solid copper tape. It can even be both. And, finally, covering all of that, is an outer jacket made of material suitable for the environment in which the cable is installed and will remain. Coax is cable used indoors and outdoors and can be used for very long distances. You see cables can be run exposed outdoors, overhead, underground, or inside a building as well. Cables can also be installed in the free air or in conduit or other raceways for protection. They can even be installed under water and in other special conditions.

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