Archive for August 2018

Digital Subscriber Line:

Digital Subscriber Line:




a. is a fairly recent approach to provide higher data transmission rates across traditional voice circuits in the local loop
b. combines analog transmission and frequency division multiplexing
c. involves the use of a customer premises equipment (CPE)
d. uses a combination of amplitude and phase modulation
e. all of the above


Answer: all of the above

Inverse multiplexing means:

Inverse multiplexing means: 




a. combining several low speed circuits to enable them to be transmitted across one high speed circuit
b. multiplexing from the terminal to the host, rather than from the host to the terminal
c. combining high speed circuits to enable them to be transmitted across one low speed circuit
d. inverting the frequencies used for transmission across a low speed circuit for switching to a digital circuit
e. multiplexing to a codec, rather than to a modem


Answer: combining several low speed circuits to enable them to be transmitted across one high speed circuit

Statistical time division multiplexers differ from time division multiplexers because they:

Statistical time division multiplexers differ from time division multiplexers because they: 




a. can cause time delays when all devices are being used for data transmission at the same time
b. take idle time of terminals into account to increase circuit throughput
c. use a complicated statistical formula to allocate time slots
d. all of the above
e. none of the above



Answer: all of the above

Which of the following types of multiplexing is least efficient for data transmission?

Which of the following types of multiplexing is least efficient for data transmission? 




a. frequency division multiplexing
b. statistical time division multiplexing
c. statistical frequency division multiplexing
d. time division multiplexing
e. wave division multiplexing



Answer: frequency division multiplexing

Frequency division multiplexing:

Frequency division multiplexing: 




a. operates by statistically time slicing the signal
b. operates by dividing the signal into different frequencies
c. uses a codec that divides signals into different channels
d. operates by time slicing the signal
e. operates by light dividing the signal


Answer: operates by dividing the signal into different frequencies

The type of multiplexer that divides the circuit horizontally into different light frequencies that are transmitted simultaneously across many channels is

The type of multiplexer that divides the circuit horizontally into different light frequencies that are transmitted simultaneously across many channels is 



a. wave division multiplexer
b. time division multiplexer
c. statistical time division multiplexer
d. frequency division multiplexer
e. statistical frequency division multiplexer


Answer: wave division multiplexer

A 56K modem that uses the V.90 standard:

A 56K modem that uses the V.90 standard:



a. never has problems with noise on the telephone line
b. can recognize an 8-bit digital symbol 8000 times per second
c. transmits 56,000 different symbol changes per second at all times
d. can be used at full capacity on all North American telephone lines
e. currently has 56K transmission rates in both upstream and downstream channels


Answer: can recognize a 8-bit digital symbol 8000 times per second

__________ refers to the difference between the original analog data and the approximation of that data using the techniques for translating from analog data to digital signals.

__________ refers to the difference between the original analog data and the approximation of that data using the techniques for translating from analog data to digital signals.




a. quantizing error
b. handshaking phase
c. modulating frequency
d. POTS anomaly
e. amplitude Trellis effect



Answer: quantizing error

Codec refers to:

Codec refers to:




a. codependent decreasing compression
b. co- Digital Equipment Corporation
c. Codd's laws for data relations
d. code/decode
e. continuous operational digital energy communication



Answer: code/decode

When V.34 modems initially connect, they must go through a ____________ sequence to test the circuit and determine the optimum combination of symbol rate and modulation technique that will produce the highest throughput.

When V.34 modems initially connect, they must go through a ____________ sequence to test the circuit and determine the optimum combination of symbol rate and modulation technique that will produce the highest throughput.




a. frequency division
b. wave division
c. handshaking
d. Trellis-coded modulation
e. point of presence



Answer: handshaking

Which statement is false about modems?

Which statement is false about modems?




a. modems are usually used in pairs (2 at a time)
b. a receiving modem demodulates and a sending modem modulates
c. most modems support several modem standards so that they can communicate with a variety of modems
d. modems may operate at a lower speed that that for which they are rated, especially if they detect noise in the communication line
e. modems must always be internal to the computer


Answer: modems must always be internal to the computer

The acronym, Modem, stands for _________________.

The acronym, Modem, stands for _________________.




a. multiplexing/demultiplexing
b. more/demote
c. Mode-M technique
d. modulator/demodulator
e. Mod emulation technique


Answer: modulator/demodulator

Which of the following statements is true?

Which of the following statements is true?




a. the longer the distance of a telephone wire between sender and recipient, the lower the bandwidth across that wire
b. the shorter the distance of a telephone wire between sender and recipient, the lower the bandwidth across that wire
c. bandwidth is constant across any wire, therefore distance is not relevant
d. the longer the distance of a telephone wire between sender and recipient, the higher the bandwidth across that wire
e. bandwidth is not a term that can be used when discussing telephone transmissions


Answer: the longer the distance of a telephone wire between sender and recipient, the lower the bandwidth across that wire

To get more "bandwidth" in a digital transmission, you must:

To get more "bandwidth" in a digital transmission, you must:




a. increase the range of frequencies available for a transmission
b. increase the loudness per transmission
c. decrease the bits per second transmission speed
d. increase the phase shifts per transmission
e. increase the baud rate per transmission



Answer: increase the range of frequencies available for a transmission

The typical range of human hearing is:

The typical range of human hearing is:



a. 0 to 4,000 Hz
b. 0 to 1,200 Hz
c. 20 to 14,000 Hz
d. 0 to 300 Hz
e. 0 to 56,000 Hz


Answer: 20 - 14,000 Hz

TCM stands for:

TCM stands for:




a. Tandem Control Microprocessor, a hardware feature of front end processors used to manage and control data communications
b. Telephone Call Manager, a software package to monitor and report on telephone usage
c. Trellis coded modulation, a technique that combines phase modulation and amplitude modulation
d. Threaded Code Messaging, a data communications transmission technique in which all redundant bits are stripped before sending and replaced upon receipt of the message
e. True Calling Measures, one telephone company's method for changing customers


Answer: trellis coded modulation: a technique that combines phase modulation and amplitude modulation

__________ is a modulation technique that combines two different amplitude combinations with eight different phase combinations modulation to send four bits per wave, or symbol.

__________ is a modulation technique that combines two different amplitude combinations with eight different phase combinations modulation to send four bits per wave, or symbol.




a. quadrature amplitude modulation
b. time division multiplexing
c. synchronous digital line control
d. pulse code modulation
e. baseband signaling



Answer: quadrature amplitude modulation

The direction in which the sound wave begins is known as:

The direction in which the sound wave begins is known as:




a. amplitude, which our ears detect as loudness
b. frequency, which our ears detect as pitch
c. phase
d. bandwidth
e. furlong



Answer: phase

________ is not a type of digital signaling technique.

________ is not a type of digital signaling technique.




a. Non-return-to-zero signaling
b. Unipolar signaling
c. Manchester encoding
d. Return-to-zero signaling
e. Data rate signaling


Answer: Data rate signaling

Which of the following statements is correct?

Which of the following statements is correct?




a. Parallel transmission is most often used for sending data on a circuit that is made up of one wire.
b. Parallel transmission is distinguished from serial transmission by the fact that the transmitting device sends a single bit, then a second bit, and so on, until all the bits are transmitted.
c. Parallel transmission is only used for analog data.
d. Serial transmission is considerably slower than parallel transmission.
e. Parallel transmission is the same as serial transmission.



Answer: serial transmission is considerably slower than parallel transmission

Which of the following is a byte, under the normal definition?

Which of the following is a byte, under the normal definition?




a. 1
b. a special character that is used for Apple computers only
c. 0
d. 325
e. 8 consecutive bits, such as 00011100, that represent one unit or character


Answer: 8 consecutive bits, such as 00011100, that represent one unit or character

Transmission speeds:

Transmission speeds:




a. are the same among all media
b. are not a factor in selecting a media because all media have more than enough speed to serve current communication demands
c. are a constant, 56Kbps, for all media types
d. differ widely among media
e. always have a direct correlation with security


Answer: differ widely among media

Which of the following media is the least secure?

Which of the following media is the least secure? 



a. coaxial cable
b. unshielded twisted pair
c. shielded twisted pair
d. fiber optic cable
e. infrared



Answer: infarared

Microwave transmission:

Microwave transmission: 




a. is a type of high frequency radio communication
b. requires a clear line-of-sight path
c. is typically used for long distance data transmission
d. does not require the laying of any cable
e. all of the above


Answer: all of the above

The earliest type of fiber optic systems were:

The earliest type of fiber optic systems were: 




a. Graded index multimode
b. Attenuated
c. Multimode
d. Single mode
e. Step mode


Answer: multimode

The two basic types of media are:

The two basic types of media are: 




a. statistical and frequency
b. guided and wireless (radiated)
c. local and wide area
d. attenuator and Gaussian
e. duplexed and non-duplexed


Answer: guided and wireless (radiated)

Which of the following is not a key advantage of digital transmission?

Which of the following is not a key advantage of digital transmission?



a. It permits only low transmission rates.
b. It is more efficient.
c. It is simpler to integrate voice, video, and data on the same circuit.
d. It is more secure.
e. It produces fewer errors.


Answer: It permits only low transmission rates

Two fundamentally different types of data are:

Two fundamentally different types of data are:



a. DSL and ADSL
b. asymmetric and symmetric
c. Microsoft and IBM
d. digital and analog
e. local area and wide area


Answer: digital and analog
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