Telecommunication Test II: Multiplexing, Modulation, and Fiber Optic

Q1. Synchronous

1. Asynchronous
2. Isochronous
3. None of the above

Q2. Full Duplex

1. Half Duplex
2. Simplex
3. All of the above

Q3. Modulation

1. De-modulation
2. Multiplexing
3. De-multiplexing

Q4. TDM

1. WDM
2. CDM
3. All of the above

Q5. FDM

1. TDM
2. WDM
3. CDM

Q6. Electrical

1. Light
2. Electromagnetic
3. All of the above

Q7. Less Susceptible

1. More Susceptible
2. Not Susceptible
3. None of the above

Q8. Fiber Optic

1. Twisted Pair Cable
2. Coaxial Cable
3. Both B & C

Q9. Reflected

1. Refracted
2. Travelling along the boundary
3. None of the above

Q10. Digital

1. Analogue
2. Both A & B
3. None of the above

Q11. Phase and in Amplitude

1. Phase and Frequency
2. Amplitude and Frequency
3. All of the above

Q12. Increased Unused Slots

1. Decrease the Unused Slots (Maybe)
2. Eliminating Unused Slots
3. Do Not Deal with Unused Slots

Q13. Mathematical Formula

1. Analogue Signal
2. Digital Signal
3. Any Signal
4. All of the above

Q14. 1000bps

1. 2000bps
2. 4000bps
3. 6000bps

Q1: Write down two differences of infrared and laser communication.

Infrared: 1- Type of electromagnetic energy like visible light but falls outside range of visible to human eyes. 2- Any thin things can block the signal such as wall or paper, for example, remote control.

Laser communication: 1- Communication follows line to line where require clear unobstructed on the both communication laser don't cover bored area. 2- Can use on two buildings.

Q3: Describe with diagram how twisting two wires of twisted pair cable is better than leaving the wires parallel.

1. The top wire absorbs 20 units, and the bottom wire absorbs 12, producing a difference of 8

B) Each of the two wires is on top one-half of the time, which means each wire absorbs the same amount of radiation

- Because twisting two wires make them less susceptible to electronic noise than parallel.

Q4: Write down at least two advantages and two disadvantages of fiber optic.

Advantages:

• Immune to electrical noise
• Less signal attenuation
• Higher bandwidth

Disadvantages:

• High cost
• Can't carry electrical power of terminal cable

Part 3:

Q1: What do you mean by modulation? Explain any two types of modulation with...

Modulation refers to changes made in a carrier according to the information being sent

• Modulation takes two inputs: 1- Carrier 2- Signal

First type of modulation: Amplitude Modulation (AM)

- AM varies the amplitude of a carrier in proportion to the information being sent.

- The carrier continues oscillating at a fixed frequency, but the amplitude of the wave varies

Second type of modulation: Frequency Modulation (FM)

In FM, frequency changes according to the signal:

• When the signal is stronger, the carrier frequency increases slightly
• When the signal is weaker, the carrier frequency decreases slightly

Q3: Difference between optical fiber and copper.

Optical fiber:

• Immune to electrical noise
• Less signal attenuation
• Higher bandwidth

Copper:

• Lower overall cost
• Less expertise
• Less easily broken

Q4. Definition of multiplexing and draw diagram of time division multiplexing

Multiplexing refers to the combination of information streams from multiple sources for transmission over a shared medium

Q5. Definition of dispersion of optical fiber and how we minimize it?

Dispersion is a serious problem for long optical fibers

Telecommunication Test II

What happens if a sender does not have data ready to send at all times?

The answer lies in a technique known as framing:

Block of bytes known as a frame. To ensure that the sender and receiver stay synchronized.

What is twisted pair and what is coaxial cable. Which one is better and why?

Each of the two wires is on top one-half of the time, which means each wire absorbs the same amount of radiation.

The wiring has a thick metal shield formed from braided wires that completely surround a center (inner) wire that carries the signal

Coaxial cable has a metal shield therefore it is better because it is less affected by the high frequencies and noise.

Why does the light travel around bend in the fiber?

When light encounters the boundary between two substances

Its behavior depends on the density of the two substances and the angle at which the light strikes the boundary

Using light energy and optical fibers

Laser communication and infrared (IR) communication (Definitions)

IR is a form of electromagnetic radiation that behaves like visible light but falls outside the range that is visible to a human eye

Laser is a pair of devices with a beam that follows the line-of-sight.

Laser long distance and the infrared short distance

IR covers broad area and can be attractive for laptop computers while Laser requires the devices to be aligned. Laser is especially useful in cities and to transmit between buildings.

Simplex, half-duplex, and full-duplex transmission (Multiple Choice)

Synchronous and asynchronous transmission (MCQ)

Time Division Multiplexing (TDM):

Basic types of multiplexing with explaining 2 of them and drawing 2 of them

Chapter 9 (L3):

Slide 30 (MCQ) 'Simplex'

Simplex: a simplex mechanism can only transfer data in a single direction

It is analogous to broadcast radio or television Figure 9.8a illustrates simplex communication

Chapter 7(L4):

Slide 12 + 13 (short answer questions)

What's the difference between the twisted pair and the copper wiring ?

What's the difference between the twisted pair and coaxial cable?

The coaxial cable is less flexible than the twisted pair

The coaxial can resist the noise more than the twisted pair

The twisted pair has two wires while the coaxial cable has an only

The coaxial has a better shield which surround the inner wire.

Slide 15 (MCQ)

Slide 28 (short answer question)

4 Advantages and disadvantages for optical fiber ?

4- High speed of transmission .

Disadvantages

Easy to brake - need expertise for installation - expensive - not applied in any were - communication is one direction

What happens if a sender does not have data ready to send at all times?

The answer lies in a technique known as framing:

Block of bytes known as a frame. To ensure that the sender and receiver stay synchronized.

Chapter 10(L5):

Slides 7, 8, 9, 10, 11, 12 (long answer question)

Slide 15 (MCQ)

Modulation to refer to changes made in a carrier Modulation according to the information being sent

Takes two inputs a carrier and a signal

There are three primary techniques that modulate an electromagnetic carrier according to a signal:

Amplitude modulation the carrier continues oscillating at a fixed frequency, but the amplitude of the wave varies.

Frequency modulation In FM, the amplitude of the carrier remains fixed when the signal is stronger, the carrier frequency increases slightly, and when the signal is weaker, the carrier frequency decreases slightly

Phase shift modulation One of the properties of a sine wave is its phase, the offset from a reference time at which the sine wave begins

Chapter 11(L6):

Slide 7 (MCQ)

Slide 26 (MCQ)

Explain 2 of the four basic types of multiplexing and define multiplexing with diagram?

Multiplexing to refer to the combination of information streams from multiple sources for transmission over a shared medium

Frequency Division Multiplexing (FDM): set of radio stations can transmit electromagnetic signals simultaneously

Wavelength Division Multiplexing (WDM)

Time Division Multiplexing (TDM): multiplexing in time simply means transmitting an item from one source, then transmitting an item from another source, and so on

Code Division Multiplexing (CDM)