Chapter 2

Question 1

converting analog data to digital signals is generally called

Answer 1

digitization

Question 2

the electric or electromagnetic impulses used to encode and transmit
data

Answer 2

Signals

Question 3

represented as continuous waveforms that can be at an infinite number of points between some given minimum and maximum.

Answer 3

Analog data and Analog signals

Question 4

composed of a discrete or fixed number of values, rather than a continuous or infinite number of values.

Answer 4

Digital data and Digital signals

Question 5

the height of the wave above (or below) a given reference point.

Answer 5

amplitude

Question 6

the number of times a signal makes a complete cycle within a given time frame.

Answer 6

frequency

Question 7

The length, or time interval, of one cycle is
called its

Answer 7

period

Question 8

The range of frequencies that a signal spans from minimum to maximum is called the

Answer 8

spectrum

Question 9

The ………. of a signal is the absolute value of the difference between the lowest and highest frequencies.

Answer 9

bandwidth

Question 10

The ……… of a signal is the position of the waveform relative to a given moment of time, or relative to time zero.

Answer 10

phase

Question 11

This loss of power, or loss of signal
strength, is called

Answer 11

attenuation

Question 12

The ……… is a relative measure of signal
loss or gain and is used to measure the logarithmic loss or gain of a signal.

Answer 12

Decibel (dB)

Question 13

the opposite of attenuation is called

Answer 13

Amplification

Question 14

the process of sending data over a signal by varying either its amplitude, frequency, or phase is called

Answer 14

Modulation

Question 15

The ……… digital encoding scheme transmits 1s as zero voltages and 0s as positive voltages.

Answer 15

nonreturn to zero-level (NRZ-L)

Question 16

The ……… has a voltage change at the beginning of a 1 and no voltage change at the beginning of a 0.

Answer 16

nonreturn to zero inverted (NRZI).

Question 17

the …….. encoding scheme has the following
properties: To transmit a 1, the signal changes from low to high in the middle of the interval, and to transmit a 0, the signal changes from high to low in the middle of the interval.

Answer 17

Manchester

Question 18

The ……… digital encoding scheme was used in a now extinct form of local area network (token ring) but still exists in a number of unique applications.

Answer 18

differential Manchester

Question 19

The Manchester encoding schemes are called
…….. because the occurrence of a regular transition is similar to seconds ticking on a clock.

Answer 19

self-clocking

Question 20

The number of times a signal changes value per second is called the

Answer 20

baud rate

Question 21

The ……… encoding scheme is unique among all the encoding schemes seen thus far because it uses three voltage levels.

Answer 21

bipolar-AMI

Question 22

The ……. encoding scheme takes 4 bits of
data, converts the 4 bits into a unique 5-bit sequence, and encodes the 5 bits using NRZI.

Answer 22

4B/5B

Question 23

The simplest modulation technique is

Answer 23

amplitude shift keying

Question 24

Amplitude shift keying has what weakness?

Answer 24

It is susceptible to sudden noise impulses such as the static charges created by a lightning storm.

Question 25

frequency shift keying is subject to

Answer 25

intermodulation distortion

Question 26

a phenomenon that occurs when the frequencies of two or more signals mix together and create new frequencies is called

Answer 26

intermodulation distortion,

Question 27

……… incorporates four different phase angles, each of which represents 2 bits

Answer 27

quadrature phase shift keying

Question 28

……… is commonly employed in higher-speed modems and uses each signal change to represent 4 bits (4 bits yield 16 combinations).

Answer 28

quadrature amplitude modulation

Question 29

converts analog data to a digital signal

Answer 29

pulsecode modulation (PCM).

Question 30

a …….. converts the analog data to a digital signal by tracking the analog waveform and taking “snapshots” of the analog data at fixed intervals.

Answer 30

codec

Question 31

Tracking an analog waveform and converting it to pulses that represent the wave’s height above (or below) a threshold is termed?

Answer 31

pulse amplitude
modulation (PAM)

Question 32

The frequency at which the snapshots are taken is called the ……

Answer 32

sampling rate

Question 33

It is called ………. when a codec tracks the incoming analog data by assessing up or down “steps.”

Answer 33

delta modulation

Question 34

The set of all textual characters or symbols
and their corresponding binary patterns is called a

Answer 34

data code