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Questions and Answers
What is the maximum distance that fiber optic cables can run without repeaters?
Which of the following characteristics is NOT an advantage of fiber optic cables?
Which form of unguided media travels in one direction and is generally used for point-to-point communication?
What is a significant disadvantage of using infrared signals for communication?
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What type of communication does radio waves primarily support?
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Which statement correctly describes the immunity of fiber optic cables compared to UTP cabling?
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What is the general range for infrared communication?
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Which of the following is a disadvantage of microwave communication?
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What is the primary purpose of twisting pairs in twisted-pair cables?
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Which category of unshielded twisted-pair (UTP) cables supports the highest bandwidth?
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What is a characteristic of Shielded Twisted Pair (STP) compared to Unshielded Twisted Pair (UTP)?
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What type of connector is typically used with twisted-pair cables for Ethernet connections?
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Which of the following statements about coaxial cables is true?
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What is the role of the fiber core in optical fiber cables?
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What distinguishes a crossover cable from a straight-through cable?
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Which of the following is NOT a typical use for twisted-pair cables?
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Study Notes
Transmission Media
- The physical path between the transmitter and the receiver is called the transmission medium or channel.
- The physical layer controls and is located below the transmission medium.
Guided Media
- Guided media uses a physical cable to transmit signals.
- Guided media is divided into 3 types: Twisted-pair cable, Coaxial cable, and Fiber-optic cable
- Twisted-pair cable consists of two insulated copper wires twisted in a regular spiral pattern.
- Each wire pair acts as a single communication link.
- The twists are used to reduce electrical interference from similar pairs close by, more twists means better quality.
- Twisted-pair cables are used in telephone networks and local area networks (LANs).
Unshielded Twisted Pair (UTP)
- UTP is the cheapest type of cable.
- UTP is the easiest to install.
- UTP is susceptible to external electromagnetic interference (EMI).
Shielded Twisted Pair (STP)
- STP has a metal braid or covering that reduces interference.
- STP is more expensive than UTP.
- STP is heavier and more difficult to handle than UTP.
Categories of Unshielded Twisted-Pair Cables
- CAT5e supports bandwidth of 100 MHz and data rate of 1000 Mbps.
- CAT6 supports bandwidth of 250 MHz and data rate of 1000 Mbps.
- CAT6a supports bandwidth of 500 MHz and data rate of 10 Gbps.
- CAT7 supports bandwidth of 600 MHz and data rate of 10 Gbps.
- CAT8 supports bandwidth of 2000 MHz and data rate of 25 Gbps or 40 Gbps.
RJ-45 Connector
- RJ-45 connectors are used for Ethernet cabling.
- Two types of RJ-45 connectors:
- Straight-through cabling
- Crossover cabling
Coaxial Cable
- Coaxial cable consists of three concentric sections:
- A center copper wire
- An insulating layer
- A braided copper shield.
Fiber-Optic Cable
- Fiber-optic cable consists of a core, cladding, and jacket.
- The core is made of glass or plastic fiber and carries the light signal.
- The cladding surrounds the core and has a different optical property than the core.
- The jacket protects the cable from environmental dangers.
Fiber Optics Properties
- Advantages of fiber-optic cable include:
- Higher bandwidth, supporting data rates of hundreds of Gbps.
- Smaller size and weight.
- Lower attenuation (signal loss), allowing for longer repeater spacing (up to 50 Km without repeaters).
- No crosstalk (no light leaking).
- Not affected by noise.
- Highly secure (no light leaking).
- Disadvantages of fiber optic cables include:
- Requires special skills to install.
- More expensive interfaces than electrical interfaces used with other types of cable.
Unguided Media: Wireless
- Unguided media transmits signals through air and are available to everyone with a receiving device.
- Wireless transmission uses various frequencies on the electromagnetic spectrum.
Radio Waves
- Radio waves have frequencies less than 300 GHz.
- Radio waves propagate in all directions (omnidirectional).
- Radio waves support long distances.
- Radio waves can be easily interfered with by other signals at the same frequency range.
- Used in broadcast radio (AM, FM), TV, and cellular phones.
- Radio waves are used for multicast communications (broadcast to many receivers) such as radio and television.
Microwaves
- Microwaves have frequencies from 300 MHz to 300 GHz.
- Microwaves travel in one direction (unidirectional) using line-of-sight propagation.
- Used for point-to-point communication, such as between buildings to connect their LANs.
- High-frequency microwaves cannot penetrate walls.
- Used in wireless networks and satellite communication.
- Microwaves are used for unicast communications (communication with a single receiver) such as cellular telephones, satellite networks, and wireless LANs.
Infrared
- Infrared waves have frequencies from 300 GHz to 400 THz.
- Infrared waves have a large bandwidth.
- Infrared waves can be used only for local, short-distance communication as they cannot penetrate walls.
- Infrared waves use line-of-sight propagation.
- Used in local point-to-point transmission.
- Applications include: wireless keyboards, mice, remote controls using Infrared Data Association (IrDA) protocol.
- Infrared cannot be used under direct sunlight because of interference with the sun’s infrared rays.
- IrDA operates at 75 kbps over 8 m, and 1.15 Mbps – 4 Mbps over 1 m.
- Infrared signals can be used for short-range communication in a closed area using line-of-sight propagation.
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Description
Test your knowledge on transmission media, focusing on guided media types like twisted-pair, coaxial, and fiber-optic cables. This quiz also covers the differences between unshielded and shielded twisted pair cables, along with their applications and characteristics.
