Tutorial 4: Physical Transmission Media

There are three types of physical transmission media used in communications, which include twisted pair cable, coaxial cable, and fiber optic cable. These different types of cables are typically used within buildings or placed underground between buildings. Physical transmission media is often used with Ethernet and LANs.

Twisted-Pair Cable:
One of the more frequently used transmission media fro network cabling and telephone systems. This cable consists of one or more twisted pair wires bundled together. Each of the twisted pair wires have two separate insulated copper wires that are twisted together. The wires are twisted together to in order to reduce noise.

Coaxial Cable:
Consists of a single copper wire surrounded by at least three layers. The first layer is an insulating material, then a woven braided metal, and finally a plastic outer coating. These cables are mainly used now a days for cable television network wiring, because it can be run over longer distances than twisted-pair cable.

Fiber-Optic Cable:
This cable consists of dozens or hundreds of thin strands of glass or plastic that use light to transmit the signals.Each strand is called an optical fiber, and is as thin as a human hair. inside each fiber optic cable there is an insulating glass cladding and a protective coating surrounding each optical fiber. Advantages of fiber optic cables is there capability of carrying a significant more amount of signals than wire cables, faster data transmission, less susceptible to noise from other devices, better security for signals during transmission, and smaller size. Disadvantages include more expensive than the other two cables, and can be difficult to install and modify.

http://www.cs.virginia.edu/~zaher/classes/CS457/lectures/physical.pdf
This link shows examples of the three types of cables and what they consists of, and also how they are typically used.

Secure Email Project

http://www.free-press-release.com/news-if-anna-chapman-had-used-opolis-secure-mail-1280128968.html

http://www.free-press-release.com/news/200907/1249085516.html

In the first article an american spy got arrested for emails that she had sent, if she would have used a secure email her emails would not have been as easily detected. The second article explains how doctors and patients use secure email in order to keep information confidential.

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The experience was a lot of fun and interesting. It was cool trying to make the avatar resemble me as much as I could.