2. Transmission media The means through which data is transmitted from one place to another is called transmission or communication media. There are two categories of transmission media used in computer communications.
3. 1. Bounded media/wired media Bounded media are the physical links through which signals are confined to a narrow path. They are great for LABS because they offer high speed, good security and low cast. Three common types of bounded media are used of the data transmission. These are: Coaxial Cable Twisted Pairs Cable Fiber optics cable
4. Coaxial cable: Copper Mesh Coaxial cable is the kind of copper cable used by cable TV companies between the community antenna and user homes and businesses. Coaxial cable is sometimes used by telephone companies from their central office to the telephone poles near users. Outside Insulation Insulation Copper Wire
5. Coaxial Cable Advantages coaxial cable Disadvantage coaxial cable Easy to wire Easy to expand Inexpensive Single cable failure can take down an entire network
6. Twisted Pair Cable Twisted Pair Cable The most popular network cabling is Twisted pair. It is light weight, easy to install, inexpensive and support many different types of network. There are two types of twisted pairs cabling: They are: 1. Unshielded twisted pair (UTP) 2. Shielded twisted pair (STP)
7. Unshielded twisted pair (UTP) UTP is more common. UTP cables consist of 2 or 4 pairs of twisted cable. Twisted Pair Outer Jacket Colour coded plastic installation
8. UTP Advantages of UTP Disadvantages of UTP Easy installation Capable of high speed for LAN Low cost It may be prone to radio and electrical frequency interference (it should not be too close to electric motors, fluorescent lights, etc.).
9. Shielded twisted pair (STP) It is similar to UTP but has a mesh shielding that’s protects it from EMI which allows for higher transmission rate Twisted Pair Outer Jacket Overall Shield Pair shield
10. STP If you must place cable in environments with lots of potential interference, or if you must place cable in extremely sensitive environments that may be susceptible to the electrical current in the UTP, shielded twisted pair may be the solution. Shielded cables can also help to extend the maximum distance of the cables.
11. Shielded Twisted Pair Advantages of STP: Disadvantages of STP: Shielded Faster than UTP and coaxial More expensive than UTP and coaxial More difficult installation
12. Fiber Optic Fiber optic cabling consists of a center glass core surrounded by several layers of protective materials (See fig. 5). It transmits light rather than electronic signals eliminating the problem of electrical interference. This makes it ideal for certain environments that contain a large amount of electrical interference.
13. Fiber Optic Advantages Of Fiber Optic Disadvantages Fiber Optics Fast transmission of data Low attenuation No EMI interference Very costly Hard to install
