What is digital communication?
Transmission of video signals
Transmission of analog signals
Transmission of digital pulses between communication points
Transmission of voice signals
What is digital communication?
Transmission of video signals
Transmission of analog signals
Transmission of digital pulses between communication points
Transmission of voice signals
What does BIT stand for?
Binary transmission
Bit rate
Bit error
Binary digit
What does BIT stand for?
Binary transmission
Bit rate
Bit error
Binary digit
What is bit rate?
Number of signals per hour
Number of bits passing through a channel per second
Number of bytes per minute
Total data size in bits
What is bit rate?
Number of signals per hour
Number of bits passing through a channel per second
Number of bytes per minute
Total data size in bits
What does bit error rate (BER) measure?
Probability of error in data transmission
Speed of data transmission
Total number of bits
Amount of data transmitted
What does bit error rate (BER) measure?
Probability of error in data transmission
Speed of data transmission
Total number of bits
Amount of data transmitted
What are Data Link Control Characters used for?
Facilitating orderly data flow
Encoding binary information
Representing alphanumeric symbols
Presenting data syntax
What are Data Link Control Characters used for?
Facilitating orderly data flow
Encoding binary information
Representing alphanumeric symbols
Presenting data syntax
What does Morse code represent?
The first data communication code with unequal symbols
A type of binary code
A character set for numbers only
An encoding system for graphics
What does Morse code represent?
The first data communication code with unequal symbols
A type of binary code
A character set for numbers only
An encoding system for graphics
What is the Morse code for the letter A in International Morse Code?
•--•
-•-•
--•-
•-
What is the Morse code for the letter A in International Morse Code?
•--•
-•-•
--•-
•-
What does the Baudot code represent for the letter A?
11001
00011
01110
01001
What does the Baudot code represent for the letter A?
11001
00011
01110
01001
Which character does the Baudot code '10100' represent?
A
C
H
B
Which character does the Baudot code '10100' represent?
A
C
H
B
What is the binary value for the letter E in Baudot code?
00001
01001
11001
01101
What is the binary value for the letter E in Baudot code?
00001
01001
11001
01101
Which letter corresponds to the Morse code '---'?
P
N
Q
O
Which letter corresponds to the Morse code '---'?
P
N
Q
O
What is the Morse code for the number 2?
---••
••---
•••--
•---•
What is the Morse code for the number 2?
---••
••---
•••--
•---•
What is the representation of the letter S in International Morse Code?
-•••
•••
•-•
What is the representation of the letter S in International Morse Code?
-•••
•••
•-•
Which Morse code symbol represents the letter R?
-•-•
--•
•-•
•--•
Which Morse code symbol represents the letter R?
-•-•
--•
•-•
•--•
What does the Baudot code '11010' represent?
H
F
I
G
What does the Baudot code '11010' represent?
H
F
I
G
Which character does the Baudot code '01110' represent?
A
B
D
C
Which character does the Baudot code '01110' represent?
A
B
D
C
What does ASCII stand for?
American Standard Code for Internal Communication
American Standard Code for Information Interchange
American Standard Code for Internet Communication
American Standard Code for Information Integration
What does ASCII stand for?
American Standard Code for Internal Communication
American Standard Code for Information Interchange
American Standard Code for Internet Communication
American Standard Code for Information Integration
How many bits are used in standard ASCII?
10 bits
8 bits
7 bits
6 bits
How many bits are used in standard ASCII?
10 bits
8 bits
7 bits
6 bits
What is the purpose of the 8th bit in ASCII?
Error detection
Character representation
Data encoding
Parity
What is the purpose of the 8th bit in ASCII?
Error detection
Character representation
Data encoding
Parity
Which of the following is a control character in ASCII?
@
A
1
NUL
Which of the following is a control character in ASCII?
@
A
1
NUL
What character does the binary code 01010 represent in ASCII?
S
Q
R
P
What character does the binary code 01010 represent in ASCII?
S
Q
R
P
What symbol does the binary code 00100 represent in ASCII?
D
@
SP (Space)
4
What symbol does the binary code 00100 represent in ASCII?
D
@
SP (Space)
4
Which binary code corresponds to the character 'A'?
01000010
01000011
01000000
01000001
Which binary code corresponds to the character 'A'?
01000010
01000011
01000000
01000001
What is the decimal value for the binary code 01111?
16
15
14
17
What is the decimal value for the binary code 01111?
16
15
14
17
Which character does the binary code 10010 represent in ASCII?
N
M
L
K
Which character does the binary code 10010 represent in ASCII?
N
M
L
K
What is represented by the binary code 11111 in ASCII?
FIGS (Figures)
SP (Space)
NUL (Null)
LTRS (Letters)
What is represented by the binary code 11111 in ASCII?
FIGS (Figures)
SP (Space)
NUL (Null)
LTRS (Letters)
What does EBCDIC stand for?
Extended Binary Code Decimal Interchange Code
Enhanced Binary Coded Decimal Interchange Code
Extended Binary Coded Decimal Interchange Code
Electronic Binary Code Data Interchange Code
What does EBCDIC stand for?
Extended Binary Code Decimal Interchange Code
Enhanced Binary Coded Decimal Interchange Code
Extended Binary Coded Decimal Interchange Code
Electronic Binary Code Data Interchange Code
What is the purpose of EBCDIC?
Character encoding
Data compression
Network communication
File encryption
What is the purpose of EBCDIC?
Character encoding
Data compression
Network communication
File encryption
What is the maximum decimal value represented in EBCDIC?
128
127
255
63
What is the maximum decimal value represented in EBCDIC?
128
127
255
63
Which character corresponds to the EBCDIC code 'C3'?
DC4
ETX
ACK
DC2
Which character corresponds to the EBCDIC code 'C3'?
DC4
ETX
ACK
DC2
What is the 2nd hex digit for the EBCDIC character 'A'?
B
E
C
D
What is the 2nd hex digit for the EBCDIC character 'A'?
B
E
C
D
Which control code is represented by the EBCDIC code '0C'?
BEL
DLE
FF
NUL
Which control code is represented by the EBCDIC code '0C'?
BEL
DLE
FF
NUL
What is the EBCDIC code for the character 'Z'?
5B
5C
5D
5A
What is the EBCDIC code for the character 'Z'?
5B
5C
5D
5A
What does the EBCDIC code 'C1' represent?
SI
SO
US
NUL
What does the EBCDIC code 'C1' represent?
SI
SO
US
NUL
What is the decimal value for the EBCDIC code 'F0'?
98
96
97
95
What is the decimal value for the EBCDIC code 'F0'?
98
96
97
95
Which EBCDIC character is associated with the hex code 'B1'?
SO
SI
NUL
US
Which EBCDIC character is associated with the hex code 'B1'?
SO
SI
NUL
US
Which character code is represented by the hex value '41' in EBCDIC?
B
A
D
C
Which character code is represented by the hex value '41' in EBCDIC?
B
A
D
C
What character does the EBCDIC code '5A' represent?
X
Z
W
Y
What character does the EBCDIC code '5A' represent?
X
Z
W
Y
What is the EBCDIC code for the space character?
50
40
30
20
What is the EBCDIC code for the space character?
50
40
30
20
Which code is primarily used in IBM mainframe systems?
EBCDIC
ASCII
UTF-8
ISO-8859-1
Which code is primarily used in IBM mainframe systems?
EBCDIC
ASCII
UTF-8
ISO-8859-1
What is the control code for 'Start of Text' in EBCDIC?
ETX
STX
EOT
SOH
What is the control code for 'Start of Text' in EBCDIC?
ETX
STX
EOT
SOH
What is the CCITT ALPHABET No. 5 CODE?
A 16 bit character set
A 8 bit character set
A 12 bit character set
A 7 bit character set with 128 codes
What is the CCITT ALPHABET No. 5 CODE?
A 16 bit character set
A 8 bit character set
A 12 bit character set
A 7 bit character set with 128 codes
What is unique about the CCITT ALPHABET No. 2 CODE?
It is a 12 bit code
It uses 8 bits
It has no start and stop bits
It has a parity bit
What is unique about the CCITT ALPHABET No. 2 CODE?
It is a 12 bit code
It uses 8 bits
It has no start and stop bits
It has a parity bit
What does the HOLLERITH CODE consist of?
12 bits of information with the 12th bit for parity
8 bits of information
16 bits of information
10 bits of information
What does the HOLLERITH CODE consist of?
12 bits of information with the 12th bit for parity
8 bits of information
16 bits of information
10 bits of information
Who is associated with the development of the Hollerith code?
Charles Babbage
Alan Turing
John von Neumann
Herman Hollerith
Who is associated with the development of the Hollerith code?
Charles Babbage
Alan Turing
John von Neumann
Herman Hollerith
What is parallel transmission in data communication?
Bits are transmitted using a clock signal only.
Bits are transmitted using asynchronous methods.
Bits are transmitted one at a time over a single wire.
Bits are transmitted character at a time over multiple wires.
What is parallel transmission in data communication?
Bits are transmitted using a clock signal only.
Bits are transmitted using asynchronous methods.
Bits are transmitted one at a time over a single wire.
Bits are transmitted character at a time over multiple wires.
What is the main feature of serial transmission?
Bits can be sent in both directions.
Bits are transmitted over a single line one bit at a time.
Bits are transmitted simultaneously over multiple wires.
Bits are transmitted using a clock signal only.
What is the main feature of serial transmission?
Bits can be sent in both directions.
Bits are transmitted over a single line one bit at a time.
Bits are transmitted simultaneously over multiple wires.
Bits are transmitted using a clock signal only.
What does asynchronous transmission use to control data flow?
Only a clock signal for synchronization.
No control bits at all.
Fixed time intervals between characters.
Start and stop bits at the beginning and end of each character.
What does asynchronous transmission use to control data flow?
Only a clock signal for synchronization.
No control bits at all.
Fixed time intervals between characters.
Start and stop bits at the beginning and end of each character.
What is synchronous transmission?
Data can only be sent in one direction.
Data is sent at a fixed rate with synchronized sender and receiver.
Data is sent at varying rates without synchronization.
Data is transmitted using start and stop bits.
What is synchronous transmission?
Data can only be sent in one direction.
Data is sent at a fixed rate with synchronized sender and receiver.
Data is sent at varying rates without synchronization.
Data is transmitted using start and stop bits.
What characterizes isochronous transmission?
Data is sent without any timing control.
Data is transmitted using a single wire only.
A combination of asynchronous and synchronous transmission.
Data is sent only in one direction.
What characterizes isochronous transmission?
Data is sent without any timing control.
Data is transmitted using a single wire only.
A combination of asynchronous and synchronous transmission.
Data is sent only in one direction.
What is simplex transmission?
Data transmission is bidirectional.
Data transmission requires a clock signal.
Data can be sent in multiple directions simultaneously.
Data transmission is unidirectional.
What is simplex transmission?
Data transmission is bidirectional.
Data transmission requires a clock signal.
Data can be sent in multiple directions simultaneously.
Data transmission is unidirectional.
What is the main characteristic of Simplex transmission?
Data transmission can happen simultaneously.
Data transmission is only for audio.
Data transmission is bidirectional.
Data transmission is unidirectional.
What is the main characteristic of Simplex transmission?
Data transmission can happen simultaneously.
Data transmission is only for audio.
Data transmission is bidirectional.
Data transmission is unidirectional.
What are Half-Duplex lines also called?
Two-way alternate lines.
Receive-only lines.
One-way lines.
Simultaneous lines.
What are Half-Duplex lines also called?
Two-way alternate lines.
Receive-only lines.
One-way lines.
Simultaneous lines.
What is unique about Full-Duplex transmission?
Data can only be sent one way.
Data can be transmitted in both directions at the same time.
Data transmission is not possible.
Data can only be sent in one direction at a time.
What is unique about Full-Duplex transmission?
Data can only be sent one way.
Data can be transmitted in both directions at the same time.
Data transmission is not possible.
Data can only be sent in one direction at a time.
What is a characteristic of Full/Full Duplex (F/FDX)?
Data transmission occurs in both directions at the same time but not between the same two stations.
Data can only be sent one way.
Data transmission is limited to one station.
Data transmission is only possible on two-wire circuits.
What is a characteristic of Full/Full Duplex (F/FDX)?
Data transmission occurs in both directions at the same time but not between the same two stations.
Data can only be sent one way.
Data transmission is limited to one station.
Data transmission is only possible on two-wire circuits.
What describes a Two-Wire Circuit?
It uses two wires for transmission.
It cannot support HDX transmission.
It is only for simplex transmission.
It uses four wires for transmission.
What describes a Two-Wire Circuit?
It uses two wires for transmission.
It cannot support HDX transmission.
It is only for simplex transmission.
It uses four wires for transmission.
What is the function of a Four-Wire Circuit?
It is limited to simplex transmission.
It cannot transmit data.
It uses four wires, two for signals and two for reference leads.
It uses two wires for signals only.
What is the function of a Four-Wire Circuit?
It is limited to simplex transmission.
It cannot transmit data.
It uses four wires, two for signals and two for reference leads.
It uses two wires for signals only.
What is a Switched Circuit commonly used for?
Automatically switching calls in a telephone network.
Transmitting video signals.
Sending data over the internet.
Storing data in a database.
What is a Switched Circuit commonly used for?
Automatically switching calls in a telephone network.
Transmitting video signals.
Sending data over the internet.
Storing data in a database.
What is a switched circuit?
A circuit that automatically switches a call through its destination after dialing.
A circuit that only transmits data.
A circuit that requires manual switching.
A permanent circuit for private use.
What is a switched circuit?
A circuit that automatically switches a call through its destination after dialing.
A circuit that only transmits data.
A circuit that requires manual switching.
A permanent circuit for private use.
What is a leased circuit used for?
Private use within a communication network.
Only for data transmission.
Temporary connections between locations.
Public broadcasting.
What is a leased circuit used for?
Private use within a communication network.
Only for data transmission.
Temporary connections between locations.
Public broadcasting.
What is amplitude distortion?
Distortion caused by the variation of transmission loss with frequency.
Noise interference in signals.
Crosstalk between signal paths.
Echo from the talker's voice.
What is amplitude distortion?
Distortion caused by the variation of transmission loss with frequency.
Noise interference in signals.
Crosstalk between signal paths.
Echo from the talker's voice.
What causes phase distortion?
Variations in signal amplitude.
Different velocities of propagation at different frequencies.
Echo from other signals.
External noise interference.
What causes phase distortion?
Variations in signal amplitude.
Different velocities of propagation at different frequencies.
Echo from other signals.
External noise interference.
What is crosstalk?
Amplitude distortion in signals.
Noise interference in the channel.
Undesired energy appearing in one signal path due to another.
Echo from the talker's voice.
What is crosstalk?
Amplitude distortion in signals.
Noise interference in the channel.
Undesired energy appearing in one signal path due to another.
Echo from the talker's voice.
What is the return of the talker's voice called?
Noise.
Crosstalk.
Echo.
Amplitude distortion.
What is the return of the talker's voice called?
Noise.
Crosstalk.
Echo.
Amplitude distortion.
What does amplitude-shift keying (ASK) represent?
Frequency changes in signals.
Phase changes in signals.
Digital modulation technique using amplitude changes.
Binary digit representation only.
What does amplitude-shift keying (ASK) represent?
Frequency changes in signals.
Phase changes in signals.
Digital modulation technique using amplitude changes.
Binary digit representation only.
What is an example of digital modulation technique?
Analog modulation.
Phase-shift keying (PSK).
Frequency modulation (FM).
Amplitude modulation (AM).
What is an example of digital modulation technique?
Analog modulation.
Phase-shift keying (PSK).
Frequency modulation (FM).
Amplitude modulation (AM).
What does Amplitude Shift Keying (ASK) use to represent binary states?
Phase reversal
Two power levels (high and low)
Four phases
Two frequencies
What does Amplitude Shift Keying (ASK) use to represent binary states?
Phase reversal
Two power levels (high and low)
Four phases
Two frequencies
In Frequency Shift Keying (FSK), how are binary states represented?
By two different frequencies
By two power levels
By amplitude changes
By phase shifts
In Frequency Shift Keying (FSK), how are binary states represented?
By two different frequencies
By two power levels
By amplitude changes
By phase shifts
What phase shift is used in Phase Shift Keying (PSK) to indicate a change from 0 to 1?
90°
360°
270°
180°
What phase shift is used in Phase Shift Keying (PSK) to indicate a change from 0 to 1?
90°
360°
270°
180°
In Binary Phase Shift Keying (BPSK), how many output phases are possible?
Two
One
Four
Three
In Binary Phase Shift Keying (BPSK), how many output phases are possible?
Two
One
Four
Three
How many different phases represent pairs of bits in Quadrature Phase Shift Keying (QPSK)?
Four
Five
Two
Three
How many different phases represent pairs of bits in Quadrature Phase Shift Keying (QPSK)?
Four
Five
Two
Three
What does QPSK stand for in digital modulation techniques?
Quadrature Phase Shift Keying
Quadrature Phase Shift Coding
Quadrature Phase Signal Keying
Quadrature Pulse Shift Keying
What does QPSK stand for in digital modulation techniques?
Quadrature Phase Shift Keying
Quadrature Phase Shift Coding
Quadrature Phase Signal Keying
Quadrature Pulse Shift Keying
What does QAM represent in digital modulation?
Quadrature Amplitude Method
Quadrature Amplitude Modulation
Quadrature Amplitude Measurement
Quadrature Amplitude Modulation Technique
What does QAM represent in digital modulation?
Quadrature Amplitude Method
Quadrature Amplitude Modulation
Quadrature Amplitude Measurement
Quadrature Amplitude Modulation Technique
What is the primary purpose of error detection?
To improve signal quality
To correct transmission errors
To determine when a transmission error has occurred
To enhance data transmission speed
What is the primary purpose of error detection?
To improve signal quality
To correct transmission errors
To determine when a transmission error has occurred
To enhance data transmission speed
Which technique involves transmitting each character twice?
Parity-check
Redundancy
Vertical redundancy
Horizontal redundancy
Which technique involves transmitting each character twice?
Parity-check
Redundancy
Vertical redundancy
Horizontal redundancy
What is the simplest error detection scheme?
Hamming code
Parity-check
Redundancy
Checksum
What is the simplest error detection scheme?
Hamming code
Parity-check
Redundancy
Checksum
What does even parity indicate when a bias bit is logic '0'?
A '1' means an error, '0' means an error
A '0' indicates no error, '1' means error
A '1' indicates an error, '0' means no error
A '0' indicates an error, '1' means no error
What does even parity indicate when a bias bit is logic '0'?
A '1' means an error, '0' means an error
A '0' indicates no error, '1' means error
A '1' indicates an error, '0' means no error
A '0' indicates an error, '1' means no error
What does odd parity indicate when a bias bit is logic '1'?
A '1' indicates an error, '0' means no error
A '1' indicates no error, '0' means there is an error
A '0' indicates no error, '1' means error
A '0' indicates an error, '1' means no error
What does odd parity indicate when a bias bit is logic '1'?
A '1' indicates an error, '0' means no error
A '1' indicates no error, '0' means there is an error
A '0' indicates no error, '1' means error
A '0' indicates an error, '1' means no error
What percentage of detection does vertical and horizontal redundancy check achieve?
75% detection
50% detection
100% detection
95-98% detection
What percentage of detection does vertical and horizontal redundancy check achieve?
75% detection
50% detection
100% detection
95-98% detection
What is the purpose of adding a parity bit to each character?
To encrypt the data
To increase the character length
To compress the data
To ensure the total number of 1's is odd or even
What is the purpose of adding a parity bit to each character?
To encrypt the data
To increase the character length
To compress the data
To ensure the total number of 1's is odd or even
What does VRC stand for in error detection?
Variable Redundancy Control
Vertical Redundancy Control
Vertical Redundancy Checksum
Vertical Redundancy Checking
What does VRC stand for in error detection?
Variable Redundancy Control
Vertical Redundancy Control
Vertical Redundancy Checksum
Vertical Redundancy Checking
What is the main function of Horizontal/Longitudinal Redundancy Checking (HRC or LRC)?
To compress data
To send messages faster
To encrypt messages
To determine if an error has occurred in a message
What is the main function of Horizontal/Longitudinal Redundancy Checking (HRC or LRC)?
To compress data
To send messages faster
To encrypt messages
To determine if an error has occurred in a message
What is the Block Check Sequence (BCS) associated with?
ECHOBACK
VRC
LRC
CRC
What is the Block Check Sequence (BCS) associated with?
ECHOBACK
VRC
LRC
CRC
What is Exact Count Encoding used for?
To add redundancy
To ensure the number of 1's in each character is the same
To encrypt data
To check for errors
What is Exact Count Encoding used for?
To add redundancy
To ensure the number of 1's in each character is the same
To encrypt data
To check for errors
What is the main feature of the Cyclic Redundancy Check (CRC)?
Is less reliable than VRC
Most reliable scheme for error detection
Requires 10-bit codes
Uses only odd parity
What is the main feature of the Cyclic Redundancy Check (CRC)?
Is less reliable than VRC
Most reliable scheme for error detection
Requires 10-bit codes
Uses only odd parity
How does ECHOBACK/ECHOPLEX help in error detection?
By encrypting the message
By sending a character back to the operator for error checking
By compressing the data
By increasing transmission speed
How does ECHOBACK/ECHOPLEX help in error detection?
By encrypting the message
By sending a character back to the operator for error checking
By compressing the data
By increasing transmission speed
What is the most reliable scheme for error detection?
Forward Error Correction
Retransmission
Cyclic Redundancy Check (CRC)
Symbol Substitution
What is the most reliable scheme for error detection?
Forward Error Correction
Retransmission
Cyclic Redundancy Check (CRC)
Symbol Substitution
What does the CRC character represent?
The total number of bits
The original message
The remainder of a division process
The error count
What does the CRC character represent?
The total number of bits
The original message
The remainder of a division process
The error count
What does Automatic Request for Retransmission (ARQ) do?
Detects errors without retransmission
Substitutes bad characters
Adds bits to the message
Resends a message when it is received in error
What does Automatic Request for Retransmission (ARQ) do?
Detects errors without retransmission
Substitutes bad characters
Adds bits to the message
Resends a message when it is received in error
What is the optimal size for ARQ message blocks?
256 to 512 characters
128 to 256 characters
64 to 128 characters
512 to 1024 characters
What is the optimal size for ARQ message blocks?
256 to 512 characters
128 to 256 characters
64 to 128 characters
512 to 1024 characters
What is Forward Error Correction?
A method that only detects errors
A substitute for bad characters
A request for retransmission
A scheme that detects and corrects errors without retransmission
What is Forward Error Correction?
A method that only detects errors
A substitute for bad characters
A request for retransmission
A scheme that detects and corrects errors without retransmission
Who developed the Hamming Code?
John von Neumann
Alan Turing
Claude Shannon
R. W. Hamming
Who developed the Hamming Code?
John von Neumann
Alan Turing
Claude Shannon
R. W. Hamming
What does the formula 2^n ≥ m + n + 1 represent in Hamming Code?
The relationship between data bits and Hamming bits
The size of the message
The total number of bits
The error detection rate
What does the formula 2^n ≥ m + n + 1 represent in Hamming Code?
The relationship between data bits and Hamming bits
The size of the message
The total number of bits
The error detection rate
What is Bit or Clock Synchronization used for?
Detecting errors in transmission
Identifying the start and stop of each bit transmitted
Substituting bad characters
Synchronizing message blocks
What is Bit or Clock Synchronization used for?
Detecting errors in transmission
Identifying the start and stop of each bit transmitted
Substituting bad characters
Synchronizing message blocks
What does Character Synchronization identify?
Start and stop of each individual character transmitted
Start and stop of each bit
Error correction in characters
Overall message synchronization
What does Character Synchronization identify?
Start and stop of each individual character transmitted
Start and stop of each bit
Error correction in characters
Overall message synchronization
What is Block or Message Synchronization used for?
Detecting transmission errors
Addressing the start and stop of large amounts of data
Establishing bit synchronization
Identifying individual characters
What is Block or Message Synchronization used for?
Detecting transmission errors
Addressing the start and stop of large amounts of data
Establishing bit synchronization
Identifying individual characters
What does character synchronization identify?
Electrical characteristics of balanced-voltage circuits
Transmission rate of 20 kbps
Start and stop of each individual character transmitted
Start and stop of large amounts of data
What does character synchronization identify?
Electrical characteristics of balanced-voltage circuits
Transmission rate of 20 kbps
Start and stop of each individual character transmitted
Start and stop of large amounts of data
What is block or message synchronization used for?
Performed between modems
Addresses the start and stop of large amounts of data
Identifies individual character transmission
Defines electrical characteristics of circuits
What is block or message synchronization used for?
Performed between modems
Addresses the start and stop of large amounts of data
Identifies individual character transmission
Defines electrical characteristics of circuits
What is modem or carrier synchronization performed for?
To transmit data at 20 kbps
To address large amounts of data
To properly demodulate received signals
To identify individual character transmission
What is modem or carrier synchronization performed for?
To transmit data at 20 kbps
To address large amounts of data
To properly demodulate received signals
To identify individual character transmission
What does RS 232C standard specify?
Electrical characteristics of balanced circuits
Handshaking and functions between DTE and DCE
Differential balanced voltage interface
Data rates over long distances
What does RS 232C standard specify?
Electrical characteristics of balanced circuits
Handshaking and functions between DTE and DCE
Differential balanced voltage interface
Data rates over long distances
What is the maximum transmission rate of RS 232C?
10 Mbps
300 kbps
100 kbps
20 kbps
What is the maximum transmission rate of RS 232C?
10 Mbps
300 kbps
100 kbps
20 kbps
What distance can RS 422A accommodate at 100 kbps?
300 ft
50 ft
40 ft
4000 ft (1200 m)
What distance can RS 422A accommodate at 100 kbps?
300 ft
50 ft
40 ft
4000 ft (1200 m)
What does RS 423A extend the distance and data rate capabilities to?
3 kbps at 4000 ft or 300 kbps at 40 ft
20 kbps at 50 ft
10 Mbps at 12 m
100 kbps at 4000 ft
What does RS 423A extend the distance and data rate capabilities to?
3 kbps at 4000 ft or 300 kbps at 40 ft
20 kbps at 50 ft
10 Mbps at 12 m
100 kbps at 4000 ft
What does RS 357 define an interface for?
DTE and Automatic Calling Equipment
Facsimile Terminal Equipment and VF Data Terminal Equipment
Balanced-voltage digital interface circuits
Unbalanced-voltage digital interface circuits
What does RS 357 define an interface for?
DTE and Automatic Calling Equipment
Facsimile Terminal Equipment and VF Data Terminal Equipment
Balanced-voltage digital interface circuits
Unbalanced-voltage digital interface circuits
What does RS 366 A (V.25 – CCITT Equivalent) define?
Standardization of interfaces for numerical control equipment
Interface between Facsimile Terminal Equipment and VF Data Terminal Equipment
Interface between DTE and Automatic Calling Equipment for Data Communications
General-purpose interface for DTE and DCE
What does RS 366 A (V.25 – CCITT Equivalent) define?
Standardization of interfaces for numerical control equipment
Interface between Facsimile Terminal Equipment and VF Data Terminal Equipment
Interface between DTE and Automatic Calling Equipment for Data Communications
General-purpose interface for DTE and DCE
What does RS 408 recommend?
Increase in interconnecting cable length
Interface for data terminal equipment
Standardization of interfaces between numerical control equipment and serial-to-parallel converter
Immunity to noise for data signaling
What does RS 408 recommend?
Increase in interconnecting cable length
Interface for data terminal equipment
Standardization of interfaces between numerical control equipment and serial-to-parallel converter
Immunity to noise for data signaling
What is the purpose of RS 449 (V.35 – CCITT Equivalent)?
General-purpose interface for DTE and DCE employing serial binary data interchange
Interface for facsimile terminal equipment
Standard protocol for packet networks
Interface for numerical control equipment
What is the purpose of RS 449 (V.35 – CCITT Equivalent)?
General-purpose interface for DTE and DCE employing serial binary data interchange
Interface for facsimile terminal equipment
Standard protocol for packet networks
Interface for numerical control equipment
What does X.21 interface with?
Data Terminating Equipment for Synchronous operation on Public Data Networks
DTE and DCE for packet mode
Interchange circuits for data terminal equipment
General-purpose interface for printers
What does X.21 interface with?
Data Terminating Equipment for Synchronous operation on Public Data Networks
DTE and DCE for packet mode
Interchange circuits for data terminal equipment
General-purpose interface for printers
What is X.25 used for?
Architecture for numerical control equipment
Standard protocol for interfacing a printer
Interchange definitions for data terminal equipment
Interface between DTE and DCE for Terminals Operating in the Packet Mode on Public data Networks
What is X.25 used for?
Architecture for numerical control equipment
Standard protocol for interfacing a printer
Interchange definitions for data terminal equipment
Interface between DTE and DCE for Terminals Operating in the Packet Mode on Public data Networks
What did Centronics Parallel Interface design for?
Use with their line of printers
General-purpose interface for computers
Connecting data terminals to public networks
Standardizing numerical control equipment
What did Centronics Parallel Interface design for?
Use with their line of printers
General-purpose interface for computers
Connecting data terminals to public networks
Standardizing numerical control equipment
What is the IEEE 488 Bus used for?
Connecting printers to mini and micro-computer systems
Packet mode terminal architecture
Interfacing numerical control equipment
Standardizing data terminal equipment
What is the IEEE 488 Bus used for?
Connecting printers to mini and micro-computer systems
Packet mode terminal architecture
Interfacing numerical control equipment
Standardizing data terminal equipment
What is the pin configuration of the Centronics Parallel Interface designed by Centronics Computer data Corporation?
36 pins
16 pins
48 pins
24 pins
What is the pin configuration of the Centronics Parallel Interface designed by Centronics Computer data Corporation?
36 pins
16 pins
48 pins
24 pins
What does IEEE 488 Bus stand for?
Standard Communication Bus
Universal Serial Bus
General Purpose Interface Bus
High-Speed Interface Bus
What does IEEE 488 Bus stand for?
Standard Communication Bus
Universal Serial Bus
General Purpose Interface Bus
High-Speed Interface Bus
What is the primary use of the IEEE 488 Bus?
Connecting speakers to computers
Connecting printers to mini and micro-computer systems
Connecting monitors to computers
Connecting keyboards to computers
What is the primary use of the IEEE 488 Bus?
Connecting speakers to computers
Connecting printers to mini and micro-computer systems
Connecting monitors to computers
Connecting keyboards to computers
What is one of the functions of the IEEE 488 Bus?
Remote control of monitors
Remote control of keyboards
Remote control of test instruments
Remote control of printers
What is one of the functions of the IEEE 488 Bus?
Remote control of monitors
Remote control of keyboards
Remote control of test instruments
Remote control of printers
How many pins does the interface for remote control and data acquisition from test instruments have?
16 pins
36 pins
48 pins
24 pins
How many pins does the interface for remote control and data acquisition from test instruments have?
16 pins
36 pins
48 pins
24 pins
What is digital communication?
Transmission of analog signals
Transmission of voice signals
Transmission of digital pulses between communication points
Transmission of video signals
What is bit rate?
Total data size in bits
Number of signals per hour
Number of bits passing through a channel per second
Number of bytes per minute
What does bit error rate (BER) measure?
Total number of bits
Probability of error in data transmission
Speed of data transmission
Amount of data transmitted
What are Data Link Control Characters used for?
Facilitating orderly data flow
Representing alphanumeric symbols
Encoding binary information
Presenting data syntax
What does Morse code represent?
An encoding system for graphics
A type of binary code
The first data communication code with unequal symbols
A character set for numbers only
What does ASCII stand for?
American Standard Code for Information Interchange
American Standard Code for Internal Communication
American Standard Code for Internet Communication
American Standard Code for Information Integration
What is the purpose of the 8th bit in ASCII?
Parity
Error detection
Character representation
Data encoding
What is represented by the binary code 11111 in ASCII?
LTRS (Letters)
SP (Space)
NUL (Null)
FIGS (Figures)
What does EBCDIC stand for?
Extended Binary Code Decimal Interchange Code
Electronic Binary Code Data Interchange Code
Extended Binary Coded Decimal Interchange Code
Enhanced Binary Coded Decimal Interchange Code
What is the purpose of EBCDIC?
Network communication
Data compression
File encryption
Character encoding
What is the CCITT ALPHABET No. 5 CODE?
A 8 bit character set
A 7 bit character set with 128 codes
A 12 bit character set
A 16 bit character set
What is unique about the CCITT ALPHABET No. 2 CODE?
It is a 12 bit code
It has no start and stop bits
It uses 8 bits
It has a parity bit
What does the HOLLERITH CODE consist of?
10 bits of information
8 bits of information
12 bits of information with the 12th bit for parity
16 bits of information
Who is associated with the development of the Hollerith code?
Charles Babbage
John von Neumann
Alan Turing
Herman Hollerith
What is parallel transmission in data communication?
Bits are transmitted using asynchronous methods.
Bits are transmitted using a clock signal only.
Bits are transmitted character at a time over multiple wires.
Bits are transmitted one at a time over a single wire.
What is the main feature of serial transmission?
Bits are transmitted simultaneously over multiple wires.
Bits are transmitted over a single line one bit at a time.
Bits are transmitted using a clock signal only.
Bits can be sent in both directions.
What does asynchronous transmission use to control data flow?
Start and stop bits at the beginning and end of each character.
Fixed time intervals between characters.
No control bits at all.
Only a clock signal for synchronization.
What is synchronous transmission?
Data is sent at varying rates without synchronization.
Data is sent at a fixed rate with synchronized sender and receiver.
Data can only be sent in one direction.
Data is transmitted using start and stop bits.
What characterizes isochronous transmission?
A combination of asynchronous and synchronous transmission.
Data is sent without any timing control.
Data is transmitted using a single wire only.
Data is sent only in one direction.
What is simplex transmission?
Data transmission is bidirectional.
Data transmission is unidirectional.
Data transmission requires a clock signal.
Data can be sent in multiple directions simultaneously.
What is the main characteristic of Simplex transmission?
Data transmission is bidirectional.
Data transmission is only for audio.
Data transmission is unidirectional.
Data transmission can happen simultaneously.
What are Half-Duplex lines also called?
Two-way alternate lines.
Simultaneous lines.
One-way lines.
Receive-only lines.
What is unique about Full-Duplex transmission?
Data can only be sent one way.
Data can be transmitted in both directions at the same time.
Data can only be sent in one direction at a time.
Data transmission is not possible.
What is a characteristic of Full/Full Duplex (F/FDX)?
Data can only be sent one way.
Data transmission is only possible on two-wire circuits.
Data transmission is limited to one station.
Data transmission occurs in both directions at the same time but not between the same two stations.
What describes a Two-Wire Circuit?
It uses four wires for transmission.
It cannot support HDX transmission.
It uses two wires for transmission.
It is only for simplex transmission.
What is the function of a Four-Wire Circuit?
It uses four wires, two for signals and two for reference leads.
It uses two wires for signals only.
It is limited to simplex transmission.
It cannot transmit data.
What is a Switched Circuit commonly used for?
Automatically switching calls in a telephone network.
Storing data in a database.
Transmitting video signals.
Sending data over the internet.
What is a switched circuit?
A circuit that automatically switches a call through its destination after dialing.
A circuit that only transmits data.
A circuit that requires manual switching.
A permanent circuit for private use.
What is a leased circuit used for?
Temporary connections between locations.
Private use within a communication network.
Public broadcasting.
Only for data transmission.
What is amplitude distortion?
Echo from the talker's voice.
Noise interference in signals.
Distortion caused by the variation of transmission loss with frequency.
Crosstalk between signal paths.
What causes phase distortion?
Different velocities of propagation at different frequencies.
Echo from other signals.
Variations in signal amplitude.
External noise interference.
What is crosstalk?
Amplitude distortion in signals.
Echo from the talker's voice.
Noise interference in the channel.
Undesired energy appearing in one signal path due to another.
What does amplitude-shift keying (ASK) represent?
Binary digit representation only.
Phase changes in signals.
Frequency changes in signals.
Digital modulation technique using amplitude changes.
What is an example of digital modulation technique?
Analog modulation.
Phase-shift keying (PSK).
Amplitude modulation (AM).
Frequency modulation (FM).
What does Amplitude Shift Keying (ASK) use to represent binary states?
Two frequencies
Two power levels (high and low)
Phase reversal
Four phases
In Frequency Shift Keying (FSK), how are binary states represented?
By amplitude changes
By two power levels
By two different frequencies
By phase shifts
What phase shift is used in Phase Shift Keying (PSK) to indicate a change from 0 to 1?
180°
270°
360°
90°
How many different phases represent pairs of bits in Quadrature Phase Shift Keying (QPSK)?
Four
Three
Five
Two
What does QPSK stand for in digital modulation techniques?
Quadrature Phase Signal Keying
Quadrature Phase Shift Coding
Quadrature Phase Shift Keying
Quadrature Pulse Shift Keying
What does QAM represent in digital modulation?
Quadrature Amplitude Measurement
Quadrature Amplitude Modulation Technique
Quadrature Amplitude Method
Quadrature Amplitude Modulation
What is the primary purpose of error detection?
To correct transmission errors
To determine when a transmission error has occurred
To improve signal quality
To enhance data transmission speed
Which technique involves transmitting each character twice?
Redundancy
Parity-check
Horizontal redundancy
Vertical redundancy
What does even parity indicate when a bias bit is logic '0'?
A '1' indicates an error, '0' means no error
A '0' indicates an error, '1' means no error
A '0' indicates no error, '1' means error
A '1' means an error, '0' means an error
What does odd parity indicate when a bias bit is logic '1'?
A '1' indicates an error, '0' means no error
A '0' indicates no error, '1' means error
A '0' indicates an error, '1' means no error
A '1' indicates no error, '0' means there is an error
What percentage of detection does vertical and horizontal redundancy check achieve?
100% detection
50% detection
75% detection
95-98% detection
What is the purpose of adding a parity bit to each character?
To encrypt the data
To increase the character length
To ensure the total number of 1's is odd or even
To compress the data
What does VRC stand for in error detection?
Vertical Redundancy Checksum
Vertical Redundancy Checking
Variable Redundancy Control
Vertical Redundancy Control
What is the main function of Horizontal/Longitudinal Redundancy Checking (HRC or LRC)?
To send messages faster
To compress data
To determine if an error has occurred in a message
To encrypt messages
What is Exact Count Encoding used for?
To add redundancy
To encrypt data
To ensure the number of 1's in each character is the same
To check for errors
What is the main feature of the Cyclic Redundancy Check (CRC)?
Uses only odd parity
Most reliable scheme for error detection
Is less reliable than VRC
Requires 10-bit codes
How does ECHOBACK/ECHOPLEX help in error detection?
By sending a character back to the operator for error checking
By increasing transmission speed
By compressing the data
By encrypting the message
What is the most reliable scheme for error detection?
Symbol Substitution
Retransmission
Cyclic Redundancy Check (CRC)
Forward Error Correction
What does the CRC character represent?
The original message
The total number of bits
The error count
The remainder of a division process
What does Automatic Request for Retransmission (ARQ) do?
Detects errors without retransmission
Substitutes bad characters
Adds bits to the message
Resends a message when it is received in error
What is the optimal size for ARQ message blocks?
256 to 512 characters
64 to 128 characters
512 to 1024 characters
128 to 256 characters
What is Forward Error Correction?
A scheme that detects and corrects errors without retransmission
A request for retransmission
A method that only detects errors
A substitute for bad characters
What does the formula 2^n ≥ m + n + 1 represent in Hamming Code?
The error detection rate
The total number of bits
The relationship between data bits and Hamming bits
The size of the message
What is Bit or Clock Synchronization used for?
Detecting errors in transmission
Synchronizing message blocks
Substituting bad characters
Identifying the start and stop of each bit transmitted
What does Character Synchronization identify?
Start and stop of each individual character transmitted
Start and stop of each bit
Overall message synchronization
Error correction in characters
What is Block or Message Synchronization used for?
Addressing the start and stop of large amounts of data
Establishing bit synchronization
Identifying individual characters
Detecting transmission errors
What does character synchronization identify?
Transmission rate of 20 kbps
Start and stop of large amounts of data
Start and stop of each individual character transmitted
Electrical characteristics of balanced-voltage circuits
What is block or message synchronization used for?
Defines electrical characteristics of circuits
Addresses the start and stop of large amounts of data
Identifies individual character transmission
Performed between modems
What is modem or carrier synchronization performed for?
To address large amounts of data
To identify individual character transmission
To transmit data at 20 kbps
To properly demodulate received signals
What does RS 232C standard specify?
Differential balanced voltage interface
Handshaking and functions between DTE and DCE
Data rates over long distances
Electrical characteristics of balanced circuits
What does RS 423A extend the distance and data rate capabilities to?
20 kbps at 50 ft
10 Mbps at 12 m
3 kbps at 4000 ft or 300 kbps at 40 ft
100 kbps at 4000 ft
What does RS 357 define an interface for?
Balanced-voltage digital interface circuits
Facsimile Terminal Equipment and VF Data Terminal Equipment
DTE and Automatic Calling Equipment
Unbalanced-voltage digital interface circuits
What does RS 366 A (V.25 – CCITT Equivalent) define?
General-purpose interface for DTE and DCE
Standardization of interfaces for numerical control equipment
Interface between Facsimile Terminal Equipment and VF Data Terminal Equipment
Interface between DTE and Automatic Calling Equipment for Data Communications
What does RS 408 recommend?
Immunity to noise for data signaling
Standardization of interfaces between numerical control equipment and serial-to-parallel converter
Increase in interconnecting cable length
Interface for data terminal equipment
What is the purpose of RS 449 (V.35 – CCITT Equivalent)?
Interface for numerical control equipment
Interface for facsimile terminal equipment
General-purpose interface for DTE and DCE employing serial binary data interchange
Standard protocol for packet networks
What does X.21 interface with?
General-purpose interface for printers
Data Terminating Equipment for Synchronous operation on Public Data Networks
Interchange circuits for data terminal equipment
DTE and DCE for packet mode
What is X.25 used for?
Interchange definitions for data terminal equipment
Architecture for numerical control equipment
Standard protocol for interfacing a printer
Interface between DTE and DCE for Terminals Operating in the Packet Mode on Public data Networks
What did Centronics Parallel Interface design for?
General-purpose interface for computers
Standardizing numerical control equipment
Use with their line of printers
Connecting data terminals to public networks
What is the IEEE 488 Bus used for?
Interfacing numerical control equipment
Packet mode terminal architecture
Standardizing data terminal equipment
Connecting printers to mini and micro-computer systems
What is the pin configuration of the Centronics Parallel Interface designed by Centronics Computer data Corporation?
36 pins
48 pins
16 pins
24 pins
What does IEEE 488 Bus stand for?
Universal Serial Bus
Standard Communication Bus
General Purpose Interface Bus
High-Speed Interface Bus
What is the primary use of the IEEE 488 Bus?
Connecting speakers to computers
Connecting monitors to computers
Connecting keyboards to computers
Connecting printers to mini and micro-computer systems
What is one of the functions of the IEEE 488 Bus?
Remote control of printers
Remote control of monitors
Remote control of keyboards
Remote control of test instruments
How many pins does the interface for remote control and data acquisition from test instruments have?
24 pins
48 pins
36 pins
16 pins
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