Transmission Basics in Networking: Media Characteristics & Connector Types

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  • 0:04 Transmission Media & Types
  • 5:32 Network Connectors
  • 9:10 Lesson Summary
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Lesson Transcript
Instructor: Abirami Thangavel

I have been teaching Computer Science for college students and have a master's degree with university ranking in Computer Science.

Transmission media are necessary to form a computer network, as they are the physical paths between a transmitter and a receiver. In this lesson, let's learn the types of transmission media and the connectors.

Transmission Media & Types

In network communications, a transmission medium is a physical connection or an interface between the transmitter and the receiver. There are two major categories of transmission media, namely guided and wireless (or unguided). Let us take a walk through the types of transmission media and connectors in detail in this lesson.

Let's first take a closer look at the different types of guided transmission media one at a time.

1. Twisted Pair Cable

Twisted pair cables have been around for a long time. They were mainly invented for voice transmissions. Twisted pair is a widely used medium in networking because it's lighter, cheaper, more flexible, easy to install, and provides greater speeds than coaxial cables. There are two types of twisted pair cables: the unshielded twisted pair (UTP) and the shielded twisted pair (STP). Let's take a closer look at each of them.

The unshielded twisted pair cable has 4 pairs of copper wires that are present inside a plastic sheath. These wires are twisted to protect them from interference. The only protection available for a UTP cable is a plastic sheath that is thin in size.

Unshielded Twisted Pair Cable

The shielded twisted pair cable is widely used in high-speed networks. The major difference between UTP and shielded twisted pair is that STP makes use of a metallic shield to wrap the wires. This metallic shield prevents interference to a better extent than UTP. These STP cables come with numbering; the higher the numbering, the better the interference prevention. As an example: most computer networks must go with CAT 3 or CAT 5, and nothing less than this.

Shielded Twisted Pair Cable

UTP and STP Difference

2. Coaxial Cables

The coaxial cables have a central copper conductor, surrounded by an insulating layer, a conducting shield, and the outermost plastic sheath. Thus, there are three insulation layers for the inner copper cable. There are two basic modes of data transmission in coaxial cables: baseband mode that has dedicated bandwidth, and broadband mode that has distributed cable bandwidth.

Cable TV and analog televisions mainly use coaxial cables. Coaxial cables have better resistance to cross talk than twisted pair cables. The coaxial cables are used for long distance communication. The most widely used types of coaxial cables are RG-59 and RG-6 (RG stands for 'radio guide'). RG-59 has lesser shielding and is suitable for short cable lengths and cable TV connections.

RG-6 has better insulation than RG-59 and is used for satellite TV and digital signal transmissions for better strength and longer distances.

Coaxial Cable

There are many advantages to coaxial cables, including the following:

  • High bandwidth
  • Easy and cheap installation
  • Better immunity from noise
  • Better scaling

However, there are also a number of disadvantages to coaxial cables, which include the following:

  • They're more prone to lightning strikes.
  • They cover less distance than fiber optic cables.
  • They carry less bandwidth than both fiber optic and twisted pair cables.

Now let's move onto a different type of guided transmission media.

3. Optical Fibers

Optical fibers use light waves for transmission. Crosstalk, EMI, and attenuation aren't issues with optical fibers. These cables are well-suited for voice, data, and video transmissions. Optical fibers are the most secure of all the cable media. Installation and maintenance are difficult and costly. Fiber optic cables have greater transmission speed, high bandwidth, and the signal can travel longer distances when compared to coaxial and twisted pair cables. Though the cost of optical fiber cable is less compared to co-axial and twisted pair cables, the additional optical components needed for installation make fiber optic the costliest of all the cables.

Optical Fiber Cable

The advantages of optical fibers include the following:

  • There is zero interference and covers major cities and countries.
  • They have high speed and high bandwidth.
  • They're highly secure.

There also are a number of disadvantages, including the following:

  • Installation and maintenance are difficult.
  • Cabling is costly.
  • Retrofitting an existing network is difficult, since optical fibers are incompatible with many types of electronic networking equipment.

There are two modes of operation for optical fibers. First there's single-mode fiber, which uses a single beam of light and allows communication over great distances with better transfer speed. Then there is multimode fiber, which uses multiple light beams inside a single fiber cable, has a reduced length and travel speed, and has a larger bandwidth, but signal strength is weakened.

Optical Fiber Transmission in the Form of Light Waves

Now let's take a closer look at unguided transmission media, or as it's most commonly known, wireless.

4. Wireless or Unguided Transmission Media

The features of wireless/unguided transmission media are that the signal gets broadcast without any guided medium through the air and is less secure. There are three types of wireless transmission media:

  • Radio wave
  • Infrared
  • Microwave

The advantages of unguided transmission media include the following:

  • They are useful in wireless remote accessing methods.
  • Networks can be expanded without disturbing the current users.

The disadvantages include:

  • Potential security issues.
  • They have limited speed compared to guided transmission media.

Network Connectors

The cable connector is a physical interface that connects the cables (media) to devices. The electrical connectors have both jacks (female-ended) and plugs (male-ended). The female connectors always fit into the male connectors.

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