COMMS3 (MOD 3)

Question 1

Transmission media is located

Answer 1

Below the physical layer

Question 2

Computers use ___ to represent data.

Answer 2

Signals

Question 3

Signals are transmitted in the form of

Answer 3

electromagnetic energy

Question 4

2 classes of transmission media

Answer 4

• Guided
• Unguided

Question 5

which are those that provide a conduit from one device to another

Answer 5

Guided media

Question 6

Examples of guided media

Answer 6

• twisted-pair cable
• coaxial cable
• fiber-optic cable.

Question 7

Design factors of guided media

Answer 7

• Bandwidth
• Transmission impairments
• Interference
• Number of receivers

Question 8

One of the wires carries signal, the other is used only as a ground reference

Answer 8

Twisted pair

Question 9

In twisted pair what determines the quality of the cable

Answer 9

number of twists per unit length

Question 10

Twister Pair – Transmission Characteristics

Answer 10

• needs amplifiers every 5-6km (analog)
• needs repeater every 2-3km (digital)
• digital or analog signals
• limited distance
• limited bandwidth (1 MHz)
• limited data rate (100 MHz)

Question 11

Types of twisted pair

Answer 11

• unshielded
• shielded

Question 12

Characteristics of unshielded twisted pair

Answer 12

• ordinary telephone wire
• cheap
• easy to install
• suffers from EM interference

Question 13

Characteristics of shielded twisted pair

Answer 13

• metal braid or sheathing
• expensive
• hard to handle

Question 14

Propagation method of unguided media

Answer 14

• Ground propagation (below 2 MHz)
• Sky propagation (2-30 MHz)
• Line of sight (above 30 MHz)

Question 15

Unguided media/Wireless transmission waves

Answer 15

• Radio wave
• Microwave
• Infrared

Question 16

• Typically range from 3 kHz to 300 GHz, covering various bands like AM, FM, TV, and mobile communication.
• Travel through free space and can penetrate walls, making them suitable for both indoor and outdoor communication.

Answer 16

Radio waves

Question 17

are a type of electromagnetic wave with frequencies ranging from 1 GHz to 300 GHz, used extensively in communication systems due to their high frequency and capacity for carrying data over long distances.

Answer 17

Microwaved

Question 18

uses electromagnetic waves with wavelengths longer than visible light but shorter than microwaves. Are commonly used for short-range, line-of-sight communication. Falls in the range of 300 GHz to 400 THz (wavelength: 700 nm to 1 mm).

Answer 18

Infrared

Question 19

are devices used to transmit or receive electromagnetic waves, converting electrical signals into radio waves (and vice versa). They play a critical role in wireless communication, enabling signal propagation over the air.

Answer 19

Antennas

Question 20

Types of satellite link

Answer 20

• Satellite point to point link
• Satellite Broadcast link

Question 21

Characteristic of line of sight transmission

Answer 21

• Free space loss
• loss of signal with distance
• Atmospheric Absorption
• from water vapour and oxygen absorption
• Multipath
• multiple interfering signals from reflections refraction
• bending signal away from receiver