CHAPTER 3

Question 1

Data must be transformed to __________ signals to be transmitted.

Answer 1

electromagnetic

Question 2

Data can be ________ or _________.

Answer 2

analog or digital

Question 3

Analog data take __________
values.

Digital data take _________ values.

Answer 3

continous and discrete

Question 4

Signals can be analog or digital. Analog signals can have an _______ number of values in a range; digital , signals can have only a ___________ number of values.

Answer 4

infinite, limited

Question 5

in data communications, we commonly use _______and ________ signals

Answer 5

periodic analog signals and nonperiodic digital signals.

Question 6

________and ________ are the inverse of each other.

Answer 6

Frequency and period

Question 7

_______________ is the rate of change with respect to time

Answer 7

Frequency

Question 8

_____________describes the position of the waveform relative to time O.

Answer 8

Phase

Question 9

A complete sine wave in the time domain can be represented by ____________

Answer 9

one single spike in the frequency domain.

Question 10

A single-frequency sine wave is not useful in data communications; we need to send a composite signal, a signal made of many simple sine waves.

true or false

Answer 10

TRUE

Question 11

According to Fourier analysis, any composite signal is a combination of simple sine waves with different ________, __________ and _________

Answer 11

frequencies, amplitudes, and phases.

Question 12

The bandwidth of a composite signal is the difference between__________and __________

Answer 12

the highest and the lowest frequencies contained in that signal.

Question 13

_________ is a composite analog signal with an infinite bandwidth.

Answer 13

A digital signal

Question 14

Baseband transmission of a digital signal that preserves the shape of the digital signal is possible only if we have a low-pass channel with an infinite or very wide bandwidth.

true or false

Answer 14

true

Question 15

If the available channel is a bandpass channel, we cannot send a digital signal directly to the channel; we need to convert the digital signal to an analog signal before transmission.

true or false

Answer 15

true

Question 16

For a noiseless channel, the Nyquist bit rate formula defines the theoretical maxi- mum bit rate. For a noisy channel, we need to use the Shannon capacity to find the maximum bit rate.

true or false

Answer 16

true

Question 17

_________, ___________ and _________ can impair a signal.

Answer 17

Attenuation, distortion, and noise

Question 18

____________ is the loss of a signal’s energy due to the resistance of the medium.

Answer 18

Attenuation

Question 19

_________________ is the alteration of a signal due to the differing propagation speeds of each of the frequencies that make up a signal.

Answer 19

Distortion

Question 20

___________ is the external energy that corrupts a signal.

Answer 20

Noise

Question 21

______________ defines the number of bits that can fill the link.

Answer 21

The bandwidth-delay product

Question 22

_____________ defines how long it takes for an entire message to completely arrive at the destination from the time the first bit is sent out from the source.

Answer 22

The latency or delay

Question 23

We can say that latency is made of four components: _________, ___________, ___________ and ____________

Answer 23

propagation time, transmission time, queuing time and processing delay.

Question 24

_________ is a measure of how fast we can actually send data through a network.

Answer 24

throughput

Question 25

____________ refers to the amount of time, in seconds, a signal needs to complete 1 cycle.

Answer 25

Period