Chapter 2 – Basic concepts of Data and Signals

Question 1

Analog signal

Answer 1

• Varies over a continuous range with respect to:
- Sound
- Light
- Radio waves
• Measured in Volts
• Frequency:
- Measured in Hertz (Hz)
• Example:
- Human voice
• Shortcomings of analog data and analog signals:
- Difficult to separate noise from the original wave form

Question 2

Digital signal

Answer 2

• Has discrete set of values
• Sequence of voltage:
- Represented in binary form
• Examples:
- Computer
- Computer-related equipment
• Easy to separate the original wave form from the noise
• Modulation:
- Digital signal is converted to analog form
• Demodulation:
- Analog signal is converted to digital form
• Device (Modulation & Demodulation):
- Modem

Question 3

Noise

Answer 3

• Unwanted electrical/electromagnetic energy
	- Degrades the quality of:
		~ Signals
		~ Data
• Buzzing sound

Question 4

Noise caused by what?

Answer 4

• Electrical motor
• High voltage line
• Lightning

Question 5

Transmitting analog data using analog signals

Answer 5

• Analog waveform:
- Transformed to another analog wave form
~ Performed under modulation
• Modulation:
- Process of sending data over a single by either:
~ Amplitude
~ Frequency
~ Phase
• Examples:
- Telephones, FM radio, broadcast TV, cable television

Question 6

Transmitting digital data with digital signals

Answer 6

• 1s and 0s of digital data:
	- Converted to the proper physical form
		~ Transmitted over a wire or airwave
• Digital encoding schemes:
	- Non return to Zero Digital
	- Manchester digital
		~ Used to convert the 0s of 1s of digital data into the appropriate transmission form

Question 7

Transmitting digital data with analog signals

Answer 7

• Modem:
- Modules digital data onto an analog signal
- Demodulates the analog data back to digital data
• Modulation technique:
- Converts digital data to an analog signal
• Example:
- Telephone system

Question 8

Transmitting analog data with digital signals

Answer 8

• Transmit analog data over a digital medium
• Digitization:
	- Convert analog data to digital signal
	- Example:
		~ Recording a CD
• Encoding techniques:
	- Code modulation
	- Delta modulation

Question 9

Modem

Answer 9

Convert digital data to an analog data and back again

Question 10

Modulation & Demodulation

Answer 10

• A communication media
• Data is converted to a signal by a computer device (modem)
• Then transmitted over a communication media

Question 11

Bandwidth

Answer 11

• Measurement of the network media’s ability to carry data
• Example:
- Network cable
~ Amount of digital signal the cable can carry based on the given time
• Measured in:
- Bits per second (bps)

Question 12

Analog transmission

Answer 12

• Can support several different frequencies at once

- Many different analogs signals/frequencies representing data can be transmitted at once

Question 13

Digital transmission

Answer 13

• Supports only one

* Uses the entire bandwidth (in a cable)

Question 14

Baseband

Answer 14

• Method of transmitting data in:
- A form of digital signal
~ Using the entire bandwidth of a cable

Question 15

Broadband

Answer 15

• Handles very large volumes of data
• Method of transmitting data in:
- Form of several analog signals at the same time
• Carries more than one frequency at a time

Question 16

General (Baseband & Broadband)

Answer 16

• Baseband:
	- Carries a single series of digital signals
• Broadband:
	- Carries two or more analog signals
• By a network conductor