Requirements: Wired media such as co-axial cable, Twisted piar cable and fiber optic cable and their respective connectors
Study of transmission media:
study of bounded channels
Wired communication media are also known as Guided media and are a type of Transmission media. This type of communication is most stable which is why it is considered better than wireless. These connections are less prone to other outer interferences. In wired communication media, wire is used to transfer data from source to destination. Wired communication media is not better for public use but can be used for professional purposes as it is more relied on wires and ports which is not in the case of wireless networks, data can be accessed from anywhere. Also, the connection speed of wired media is more as compared to wireless. The whole setup of wired media is also expensive as larger the distances more no. of cables and ports would be required and fiber optic cables are usually expensive.
1.Co-axial cable
2.Twisted pair cable
3.Optic Fiber cable
Copper conductor: A central conductor, which consists of copper. The conductor is the point at which data transmits.
Braided mesh: A braided mesh of copper helps to shield from electromagnetic interference, The braid provides a barrier against EMI moving into and out of the coaxial cable.
Protective plastic layer: An external polymer layer, which has a plastic coating. It is used to protect internal layers from damages.
Insulator: Dielectric plastic insulation around the copper conductor. it is used to maintain the spacing between the center conductor and shield.
Applications of Coaxial cable
The coaxial cables are used in Ethernet LANs and also used in MANs
- Television: Coaxial cable used for television would be 75 Ohm and RG-6 coaxial cable.
- Internet: Coaxial cables are also used for carrying internet signals, RG-6 cables are used for this.
- CCTV: The coaxial cables are also used in CCTV systems and both RG-59 AND RG-6 cables can be used.
Types of Co-axial cable
- Thicknet
- Thinnet
ThickNet: This type of coaxial cabling is used with Ethernet 10Base5 networks and is able to span distances of up to 500 meters. Originally used to directly connect computers, it eventually became popular in backbone implementations between LANs. Systems connected to the cable using an external transceiver unit than actually tapped directly into the wire. The transceiver was then connected to a network card using an Attachment Unit Interface (AUI) cable. You’ll learn more about external transceivers and AUI connections when we look at Cisco router ports.
ThinNet. A much thinner and more flexible type of coaxial cable, ThinNet is used on Ethernet 10Base2 networks and can span distances of up to 185 meters. This was usually the media of choice for connecting computers on a LAN. In ThinNet networks, computers connect to the network via a BNC-T connector attached to the network card.
Connectors for coaxial cable
Two types of connectors are commonly used with co-axial cable The most common is:
- British Naval Connector (BNC)
- Thicknet uses N-connections
2) Twisted pair cable
Twisted Pair Cables :
These are a type of guided media. It was invented by Alexander Graham Bell. Twisted pair cables have two conductors that are generally made up of copper and each conductor has insulation. These two conductors are twisted together, thus giving the name twisted pair cables. One of the conductors is used to carry the signal and the other is used as a ground reference only. The receiver uses the difference of signals between these two conductors. The noise or crosstalk in the two parallel conductors is high but this is greatly reduced in twisted pair cables due to the twisting characteristic. In the first twist, one conductor is near to noise source and the other is far from the source but in the next twist the reverse happens and the resultant noise is very less and hence the balance in signal quality is maintained and the receiver receives very less or no noise. The quality of signal in twisted pair cables greatly depends upon the number of twists per unit length of the cable.
Twisted Pair Cables are further of two types :
1. Unshielded Twisted Pair Cables (UTP) :
These are a pair of two insulated copper wires twisted together without any other insulation or shielding and hence are called unshielded twisted pair cables. They reduce the external interference due to the presence of insulation. Unshielded twisted pair cables are arranged in pairs so that we can add a new connection whenever required. The DSL or telephone lines in our houses have one extra pair in them. When UTP are arranged in pairs, each pair is coded with a different color as defined by the 25-pair color code developed by AT&T Corporation. The Electronic Industries Association divides UTP into 7 categories based on some standards. Categories are based upon cable quality where 1 is the highest quality and 7 is the lowest quality. Each cable in a category is put to a different use as needed.
2. Shielded Twisted Pair is a special kind of copper telephone wiring which is used in some commercial installations. The most common use of the shielded twisted pair kind of cabling comes in extreme cold weathers where the extra layer of outer covering makes it ideal for withstanding such temperatures or for protecting the inner constituents. As such, it is good for research in places where temperatures can go to sub-zero and can make ordinary wires useless. In the same vein, these wires can be used in heavy industrial scenarios where extreme heat is produced. The same logic which makes these wires suitable for use in cold weather makes it suitable in this scenario as well. It also makes the shielded twisted pairs suitable for use in high radiation environments which do not allow a wide leeway to humans.
Optical fiber communication channel
The communication using optical fiber cable can be a technique of transmitting data from one location to another by transmitting light pulses. At present, these cables are used for communication like sending images, voice messages, etc. The designing of these cables can be done with plastic or glass so that the data can be transmitted effectively and quickly than copper cables. These cables changed the telecom industry by playing a key role in data transmission. So these cables replaced the copper cables. Nowadays, the world is connected to the internet. So by using a light beam of a fiber optic cable, it is possible to make a phone call, video download and website checking, etc.
A cable which is used to transmit the data through fibers (threads) or plastic (glass) is known as optical fiber cable. This cable includes a pack of glass threads which transmits modulated messages over light waves. There are many advantages by using these cables over other types of communication cables like bandwidth of these cables is high, less vulnerable than metal cables to interference, less thin, lighter, and the data can be transmitted in the form of digitally. The main disadvantages of these cables are installation is expensive, more delicate and difficult to fix together.
These cables are essential for LANs. So, telecommunication companies are replacing the telephone lines by these cables. One day, all communications will use fiber optics. The design considerations of these cables mainly include appearance, ruggedness, durability, tensile strength, flammability, size, range of temperature, and its flexibility.