Deck 5: Signal Encoding Techniques

Question 1

The most familiar use of transmitting digital data using analog signals is the public telephone network.

Answer 1

True

Question 2

Bandwidth efficiency measures the efficiency with which bandwidth can be used to transmit data.

Answer 2

True

Question 3

Using two different voltage levels for the two binary digits is a difficult way to transmit digital signals.

Answer 3

False

Question 4

The modulation rate of a signal is the rate,in bits per second,that data are transmitted.

Question 5

Modulation does not permit frequency division multiplexing.

Question 6

The biphase codes are known as self-clocking codes.

Question 7

PCM starts with a continuous time,continuous amplitude signal from which a digital signal is produced.

Question 8

Some transmission media,such as optical fiber and unguided media,will only propagate analog signals.

Question 9

A category of encoding techniques known as multilevel binary addresses some of the deficiencies of the NRZ codes.

Question 10

The encoding scheme is the mapping from data bits to signal elements.

Question 11

In ________ signaling an analog or digital data source is encoded into a digital signal.

A)polar
B)carrier
C)analog
D)digital

Question 12

A scrambling coding technique based on bipolar-AMI and commonly used in North America is ________.

A)HDB3
B)ASK
C)MFSK
D)B8ZS

Question 13

In ________,the two binary values are represented by two different amplitudes of the carrier frequency.Commonly,one of the amplitudes is zero.One binary digit is represented by the presence,at constant amplitude,of the carrier,the other by the absence of the carrier.

A)amplitude shift keying
B)phase shift keying
C)frequency shift keying
D)high density bipolar-3 zeros

Question 14

A ________ converts digital data to analog signal so that it can be transmitted over an analog line.

A)modem
B)satellite
C)router
D)receiver

Question 15

The simplest form of digital encoding of ________ is to assign one voltage level to binary- one and another to binary-zero.

A)digital data
B)carrier data
C)AM data
D)analog data

Question 16

More efficient use of bandwidth can be achieved if each signaling element represents one bit.

Question 17

A digital signal is a sequence of discrete,discontinuous voltage pulses.

Question 18

Both analog and digital information can be encoded as either analog or digital signals.

Question 19

Amplitude shift keying is less susceptible to error than binary frequency shift keying.

Question 20

In general,the equipment for encoding digital data into a digital signal is more complex and expensive than digital to analog modulation equipment.

Question 21

In the ________ scheme,a binary 0 is represented by no line signal and a binary 1 is represented by a positive or negative pulse.The binary 1 pulses must alternate in polarity.

Question 22

There is a transition at the middle of each bit period in the ________ biphase coding technique.The midbit transition serves as a clocking mechanism and also as data.A low-to-high transition represents a 1,and a high-to-low transition represents a 0.

Question 23

The device used for converting analog data into digital form for transmission,and subsequently recovering the original analog data from the digital,is a ________.

A)modem
B)ASK
C)PAM
D)codec

Question 24

Frequency modulation and phase modulation are special cases of ________ modulation.

A)PM
B)FM
C)angle
D)amplitude

Question 25

A distinction needs to be made between data rate (expressed in bits per second)and ________ rate (expressed in baud)when signal encoding techniques are used.

Question 26

A common encoding technique in which each of the two modulated streams is a BPSK signal at half the data rate of the original bit stream is ________.The combined signals have a symbol rate that is half the input bit rate.

A)MPSK
B)MFSK
C)QPSK
D)QAM

Question 27

If digital signaling elements all have the same algebraic sign,all positive or all negative,then the signal is ________.

A)polar
B)unipolar
C)baseband
D)differential

Question 28

Analog data in electrical form can be transmitted as ________ signals easily and cheaply with voice transmission over voice grade lines.

A)carrier
B)broadband
C)baseband
D)modulating

Question 29

The basis for ________ signaling is a continuous constant frequency signal known as the carrier signal.

Question 30

All modulation techniques involve operation on one or more of the three fundamental frequency domain parameters: amplitude,phase and _____.

Question 31

Multiple signals,each at a different position on the spectrum,sharing the same transmission medium,is known as frequency division ________.

Question 32

The ________ code has been specified for the IEEE 802.3 (Ethernet)standard for baseband coaxial cable and twisted pair bus LANs.

A)Manchester
B)HDB3
C)differential Manchester
D)NRZ

Question 33

Because of their simplicity and relatively low frequency response characteristics,________ codes are commonly used for digital magnetic recording.

A)NRZ
B)AMI
C)VSES
D)B8ZS

Question 34

The ________ rate,expressed in baud,is the rate at which the signal level is changed.

Question 35

The three basic encoding or modulation techniques for transforming digital data into analog signals are amplitude shift keying,phase shift keying,and ________.

Question 36

In ________ signaling one logic state is represented by a positive voltage level and the other by a negative voltage level.

Question 37

NRZI is an example of ________ encoding.

Question 38

In ________ the phase of the carrier signal is shifted to represent data.

A)MFSK
B)ASK
C)FSK
D)PSK

Question 39

A coding scheme that is commonly used in Europe and Japan is the ________.

A)B8ZS
B)AMI
C)amplitude shift keying
D)HDB3

Question 40

The binary 1 represented by the absence of a line signal and the binary 0 by alternating positive and negative pulses is ________.

A)pseudoternary
B)NRZ-L
C)bipolar-AMI
D)differential Manchester

Question 41

In the differential ________ scheme a binary 0 is represented by sending a signal burst of the same phase as the previous signal burst sent.A binary 1 is represented by sending a signal burst of opposite phase to the preceding one.

Question 42

The process of converting analog data into digital data is known as ________.

Question 43

A popular analog signaling technique that is used in the asymmetric digital subscriber line is ________ modulation.

Question 44

There are two important parameters in a delta modulation scheme: the size of the step assigned to each binary digit and the ________ rate.

Question 45

The parameter known as the ________ is the ratio of the amplitude of the input signal to the carrier.