Deck 13: Data Transmission

Question 1

The two types of digital data transmission are baseband and highband.

Answer 1

False

Question 2

When data is transmitted without modulation, it is called broadband transmission.

Answer 2

False

Question 3

The three components of a data transmission system are a sending device, receiving device, and transmission medium.

Answer 3

True

Question 4

The simplest connection between sending and receiving devices is a coaxial cable.

Question 5

Coaxial connections typically use BNC connectors.

Question 6

An advantage of twisted pair cable is that cross- talk is minimized.

Question 7

Optical fiber cables get their name from originally carrying video communications.

Question 8

Optical fiber cables can support faster data rates than copper conductors.

Question 9

Optical fiber is used when a data transmission system requires a cheap transmission medium.

Question 10

In multimode propagation light propagates through the fiber core as a single ray.

Question 11

Single- mode propagation has greater bandwidth than multimode propagation.

Question 12

Wireless transmission systems do not have a physical connection between the sending and receiving systems.

Question 13

Wireless communication in the infrared frequency band are limited to line- of- sight communications.

Question 14

In general, parallel data transmission is faster than serial data transmission.

Question 15

An advantage of parallel communications is that multiple transmission lines avoid skew in the transmitted data.

Question 16

Serial- to- parallel and parallel- to- serial converters allow computers to communicate with external devices.

Question 17

In asynchronous communication systems, the sender and receiver oscillators operate at the same frequency.

Question 18

Baud rate is another term for bit rate.

Question 19

The data efficiency of a system is the percentage of the total communications time spent transmitting data bits.

Question 20

In a synchronous communications system, the receiving system provides the clock signal.

Question 21

"Return to zero"and "return to one"are types of synchronous communications that use separate clock and data lines.

Question 22

Manchester encoding is a type of synchronous communications that requires only a single line.

Question 23

Synchronous communication systems send data in groups called packets.

Question 24

In simplex communications, data always travels in the same direction.

Question 25

ASK stands for asynchronous serial keying.

Question 26

Frequency shift keying is a type of encoding in which a digital signal modulates the frequency of a higher frequency sine wave is frequency shift keying.

Question 27

Bluetooth is an example of phase shift keying.

Question 28

Quadrature amplitude modulation uses a combination of frequency shift keying and amplitude modulation.

Question 29

Each modulation state in a 16- QAM system represents a specific 4- bit group.

Question 30

A vector representation that graphically shows the symbol values and corresponding phases being transmitted by a system is called a star chart.

Question 31

A commonly used type of pulse modulation is pulse width modulation.

Question 32

Another name for pulse position modulation is pulse phase modulation.

Question 33

A modulation method used to convert the amplitude of an analog signal to digital values is pulse amplitude modulation.

Question 34

Time division multiplexing switches multiple data sources onto and off of a single transmission line in a specific sequence.

Question 35

Bit- interleaved time division multiplexing uses a start and stop bit to synchronize the multiplexing and demultiplexing of transmitted data.

Question 36

A disadvantage of bit- interleaved time division multiplexing is that the sending system must buffer data before transmitting it.

Question 37

Synchronous time division multiplexing is inefficient because a time slot must be reserved even if there is no data to transmit in that time slot.

Question 38

Statistical time division multiplexing improves channel efficiency by ensuring that every time slot contains data.

Question 39

Statistical time division multiplexing functions by using variable time slot assignments.

Question 40

FDM stands for fixed delay modulation.

Question 41

The loss of energy as a signal propagates through the transmission medium is called cross- talk.

Question 42

Most signal loss in coaxial cable or twisted pair media is because of resistance.

Question 43

Diffusion is one cause of signal attenuation in fiber optic cable.

Question 44

Conversion of optical power to heat is one result of absorption in fiber optic cables.

Question 45

Wireless media does not suffer from signal losses as do physical media like copper wire or fiber optic cable.

Question 46

The unwanted change in the shape of a waveform is referred to as modulation.

Question 47

Resistance is a major factor in causing waveform distortion in cables.

Question 48

Inductance, capacitance, and resistance in a signal wire can result in oscillations called ringing.

Question 49

Noise is an unwanted electrical disturbances caused by natural and man- made sources.

Question 50

The relative strength of a signal compared to the noise present is called the signal- to- noise ratio.

Question 51

Digital data transmission channels can be all of the following except_________.

A) wireless
B) wire cable
C) optical fiber
D) thermal transmission

Question 52

A data transmission system does not require __________.

A) a transmission medium
B) a monitoring station
C) a receiving device
D) a sending device

Question 53

The simplest connection between a sending device and receiving device is_________.

A) a coaxial cable
B) a fiber optic cable
C) a wire
D) a shielded twisted pair

Question 54

The construction of a coaxial cable does not include _________.

A) a dielectric surrounded by a copper shield
B) a center conductor
C) an insulating jacket
D) a highly reflective outer layer

Question 55

The most common type of coaxial connector is the_________.

A) banana jack
B) stereo phono jack
C) alligator clip
D) BNC connector

Question 56

EMI stands for _________.

A) excessive measured interference
B) electromagnetic interference
C) electromotive induction
D) external magnetic inductance

Question 57

Coaxial cable supports data rates up to about_________.

A) 500 MHz
B) 1 GHz
C) 5 GHz
D) 25 MHz

Question 58

The purpose of twisted pair cables is to minimize_________.

A) cross- talk
B) cabling distances
C) power dissipation
D) data transmission rates

Question 59

Shielded twisted pair cable provides more protection from _________ than unshielded twisted pair cable.

A) SNR
B) STP
C) PSK
D) EMI

Question 60

Advantages of fiber optic cable over copper cables include all of the following except _________ .

A) faster data rates
B) immunity from EMI
C) lower cost
D) transmission over longer distances

Question 61

Common fiber optic data rates are __________.

A) 10 GHz to 40 GHz
B) 500 MHz to 1 GHz
C) 50 MHz to 100 MHz
D) 1 MHz to 5 MHz

Question 62

The fiber optic core for single- mode propagation is __________.

A) much smaller in diameter than in multimode propagation
B) about the same diameter as in multimode propagation
C) much larger in diameter than in multimode propagation
D) somewhat larger in diameter than in multimode propagation

Question 63

Fiber optic cable functions due to a phenomenon called __________.

A) total internal reflection
B) absorption
C) total internal refraction
D) dispersion

Question 64

All of the following are typical connector types for fiber- optic systems except _________.

A) BNC
B) ST
C) FDDI
D) LC

Question 65

Transmission of data through space without the use of connections between sending and receiving systems is called_________ .

A) full- duplex communications
B) wireless communications
C) line- of- sight communications
D) sonar

Question 66

The ways in which radio frequency and microwave signals propagate through the atmosphere include all of the following except _________.

A) stratospheric
B) ground wave
C) line- of- sight
D) ionospheric

Question 67

Communication in the infrared region can be _________.

A) multimode
B) dispersed
C) single- mode
D) diffused

Question 68

The difference between broadband and baseband transmissions is _________.

A) broadband transmissions modulate the data
B) baseband means that the system is sending the transmission
C) baseband means that the system is receiving the transmission
D) baseband transmissions modulate the data

Question 69

Parallel data transmission _________.

A) does not have problems with data skew
B) is typically faster than serial transmission
C) does not required reduced data rates to prevent errors
D) all of the above

Question 70

A simple way to convert parallel to serial data is to use _________.

A) a FIFO memory
B) a parallel in serial out shift register
C) a full- adder
D) a binary to hexadecimal converter

Question 71

For long distance communications system typically will transmit data in _________.

A) parallel format
B) serial format
C) ASCII
D) both A and B

Question 72

An asynchronous data packet typically includes all of the following bit types except _________.

A) retry
B) data
C) stop
D) start

Question 73

To correct for drift between the sending and receiving oscillators, asynchronous communication systems _________.

A) require periodic calibration by authorized service personnel
B) coordinate transmissions with a recognized NIST time signal
C) use a third system oscillator to establish a reference frequency
D) use the start bit of each data packet to resynchronize the oscillators

Question 74

The baud rate is defined as_________.

A) twice the bit rate
B) bits per second
C) packets per second
D) symbols per second

Question 75

The bit rate is defined as __________.

A) half the baud rate
B) symbols per second
C) bits per second
D) packets per second

Question 76

Synchronous data formats include all of the following except_________.

A) duplex cycling
B) Manchester encoding
C) return to zero
D) non- return to zero

Question 77

For a return to zero data format _________.

A) a single pulse during a bit time represents a 0 and absence of a pulse represents a 1
B) a change during a bit time represents a 1 and no change represents a 0
C) a single pulse during a bit time represents a 1 and absence of a pulse represents a 0
D) the format is meaningless because there is no return to zero data format

Question 78

Synchronous data is sent in _________.

A) frames
B) bunches
C) continuous bit streams
D) packets

Question 79

The preamble of a frame _________.

A) alerts the receiver that a new frame has arrived
B) is located at the start of a frame
C) is used to synchronize the receiver's clock with that of the sender
D) all of the above

Question 80

The error check in the frame check field of a data frame consists of_________.

A) a CRC value
B) a parity bit
C) a checksum
D) any of the above