Deck 6: Error Detection and Correction

Question 1

The ratio of data bits to total bits is called the code rate .

Answer 1

True

Question 2

Redundant bits are not used by the receiver for error detection.

Answer 2

False

Question 3

A ________ error can occur in the presence of white noise when a slight random deterioration of the signal to noise ratio is sufficient to confuse the receiver's decision of a single bit.

A)burst
B)idle
C)single-bit
D)digital

Answer 3

C

Question 4

Error detection found in data link control protocols such as HDLC is not a useful technique.

Question 5

Modulo 2 arithmetic uses binary addition with no carries,which is just the exclusive-OR (XOR)operation.

Question 6

Error correction works by adding sufficient redundancy to the transmitted message.

Question 7

The simplest error detecting scheme is to append a parity bit to the end of a block of data.

Question 8

The Internet checksum is considerably less effective than the CRC.

Question 9

In ________ transmission each block of data is formatted as a frame that includes a starting and an ending flag.

A)parallel
B)asynchronous
C)analog
D)synchronous

Question 10

The characteristics that distinguish various data link configurations are topology and whether the link is half duplex or full duplex.

Question 11

________ is one of the most fundamental requirements in the transmission of a stream of bits from one device to another.

A)Standardization
B)Digitalization
C)Synchronization
D)Configuration

Question 12

In a(n)________ there is a cluster of bits in which a number of errors occur,although not necessarily all of the bits in the cluster suffer an error.

A)error burst
B)single-bit error
C)idle state
D)error detection

Question 13

CRC-32 is not used in IEEE 802 LAN standards.

Question 14

Error correction is best used with wireless applications.

Question 15

Burst errors can be caused by impulse noise.

Question 16

An error detection code simply detects the presence of an error. .

Question 17

The use of Manchester encoding is a form of synchronization.

Question 18

Single bit errors are more common and more difficult to deal with.

Question 19

Regardless of the design of the transmission system,there will be errors,resulting in the change of one or more bits in a transmitted block of data.

Question 20

In __________ transmission systems,an error occurs when a binary 1 is transmitted and a binary 0 is received,or a binary 0 is transmitted and a binary 1 is received.

A)analog
B)digital
C)parallel
D)none of the above

Question 21

Three approaches are in common use for coping with data transmission errors: error-detection codes,error-correction codes,and __________ protocols.

Question 22

The ratio of redundant bits to data bits,(n - k)/k ,is called the __________ of the code.

A)redundancy
B)coding gain
C)code rate
D)fixed parity

Question 23

Error correction works by adding ________ to the transmitted message.

A)decoding
B)clarification
C)error burst
D)redundancy

Question 24

A way of viewing the CRC process is to express all values as ________ in a dummy variable X with binary coefficients.

Question 25

The ________ is a measure of how much additional bandwidth is required to carry data at the same data rate as without the code.

Question 26

In ________ transmission systems,an error occurs when a bit is altered between transmission and reception.

A)analog
B)digital
C)idle
D)guided

Question 27

A ________ error is an isolated error condition that alters one bit but does not affect nearby bits.

Question 28

The use of coding allows a reduction,referred to as the ________,and defined as the reduction in decibels to achieve a specified BER of an error correcting coded system compared to an uncoded system using the same modulation.

A)code rate
B)fixed coding
C)coding gain
D)block code

Question 29

Correction of errors using an error detecting code requires that block of data to be ________.

A)skipped over
B)deleted
C)retransmitted
D)streamed

Question 30

The ________ is a measure of how much additional bandwidth is required to carry data at the same data rate as without the code.

Question 31

FEC codes are designed not just to detect but correct errors,avoiding the need for __________.

Question 32

The __________ d(v1 ,v2)between two n -bit binary sequences v1 and v2 is the number of bits in which v1 and v2 disagree.

A)check bits
B)FCS
C)ECC
D)Hamming distance

Question 33

___________ operates in a fashion similar to error detection but is capable of correcting certain errors in a transmitted bit stream.

Question 34

The data,plus preamble,postamble and control information are called a ________.

Question 35

The __________ is the reduction,in decibels,to achieve a specified BER of an error-correcting coded system compared to an uncoded system using the same modulation.

A)FEC
B)Hamming distance
C)coding gain
D)checksum

Question 36

The ratio of redundant bits to data bits is called the ________ of the code.

Question 37

A ___________ is an isolated error condition that alters one bit but does not affect nearby bits.

A)parity error
B)burst error
C)single-bit error
D)streaming error

Question 38

The _________ is a string of 1-bit storage devices with each device having an output line,which indicates the value currently stored,and an input line.

A)shift register
B)parity
C)digital logic
D)none of the above

Question 39

The __________ is a measure of how much additional bandwidth is required to carry data at the same data rate as without the code.

A)burst rate
B)code rate
C)stream rate
D)idle rate

Question 40

Redundant bits are used by the _________ for the purpose of error detection or correction.

Question 41

In an ??????__________ ,there is a cluster of bits in which a number of errors occur,although not necessarily all of the bits in the cluster suffer an error.

Question 42

A __________ error can occur in the presence of white noise.

Question 43

Forward error correction schemes are frequently used in __________ transmission, where retransmission schemes are highly inefficient and error rates may be high.

Question 44

The simplest error-detecting scheme is to append a __________ bit to the end of a block of data.

Question 45

An ___________ is a group of bits in which two successive erroneous bits are always separated by less than a given number x of correct bits.