Data Comm/Networks Fahy Ch 7
A simple sine wave can be represented by one single spike in the _____ domain. A) amplitude B) time C) frequency D) phase
C) frequency
The first step in PCM is ________. A) quantization B) modulation C) sampling D) None of the choices are correct.
C) sampling
In Manchester and differential Manchester encoding, the transition at the middle of the bit is used for __________. A) bit transfer B) baud transfer C) synchronization D) None of the choices are correct.
C) synchronization
Which encoding method uses alternating positive and negative values for 1s? A) NRZ-I B) RZ C) Manchester D) AMI
D) AMI
________ is the process of converting digital data to a digital signal. A) Block coding B) Line coding C) Scrambling D) All of the choices are correct.
D) All of the choices are correct.
_________ can impair a signal. A) Attenuation B) Distortion C) Noise D) All of the choices are correct.
D) All of the choices are correct.
_______ encoding has a transition at the middle of each bit. A) RZ B) Manchester C) Differential Manchester D) All the choices are correct.
D) All the choices are correct.
___________ conversion involves three techniques: line coding, block coding, and scrambling. A) Analog-to-digital B) Digital-to-analog C) Analog-to-analog D) Digital-to-digital
D) Digital-to-digital
Which multiplexing technique is used for analog signals? A) FDM B) TDM C) WDM D) PDM
D) PDM
_______ describes the position of the waveform relative to time 0. A) Amplitude B) Time C) Frequency D) Phase
D) Phase
Which of the following is not an analog-to-analog conversion? A) AM B) PM C) FM D) QAM
D) QAM
________ uses two carriers, one in-phase and the other quadrature. A) ASK B) PSK C) FSK D) QAM
D) QAM
PCM is an example of _______ conversion. A) digital-to-digital B) digital-to-analog C) analog-to-analog D) analog-to-digital
D) analog-to-digital
Which of the following is not a guided medium? A) twisted-pair cable B) coaxial cable C) fiber-optic cable D) atmosphere
D) atmosphere
When propagation speed is multiplied by propagation time, we get the ________. A) throughput B) wavelength of the signal C) distortion factor D) distance a signal or bit has traveled
D) distance a signal or bit has traveled
In a time-domain plot, the horizontal axis is a measure of ________. A) signal amplitude B) frequency C) phase D) time
D) time
________ is a type of transmission impairment in which the signal loses strength due to the resistance of the transmission medium. A) Attenuation B) Distortion C) Noise D) Decibel
A) Attenuation
_______ provides redundancy to ensure synchronization and inherent error detection. A) Block coding B) Line coding C) Line coding or block coding D) None of the choices are correct
A) Block coding
________ is normally referred to as mB/nB coding; it replaces each m-bit group with an n-bit group. A) Block coding B) Line coding C) Scrambling D) None of the choices are correct.
A) Block coding
Which multiplexing technique shifts each signal to a different carrier frequency? A) FDM B) TDM C) WDM D) PDM
A) FDM
The idea of RZ and the idea of NRZ-L are combined into the ________ scheme. A) Manchester B) differential Manchester C) Manchester or differential Manchester D) None of the choices are correct.
A) Manchester
In ______, the change or lack of change in the level of the voltage determines the value of the bit. A) NRZ-I B) NRZ-L C) NRZ-I or NRZ-L D) None of the choices are correct.
A) NRZ-I
Which of the following encoding methods does not provide for synchronization? A) NRZ-L B) RZ C) NRZ-I D) Manchester
A) NRZ-L
________ provides synchronization without increasing the number of bits. A) Scrambling B) Line coding C) Block coding D) None of the choices are correct.
A) Scrambling
_______ data are continuous and take continuous values. A) analog B) digital C) analog or digital D) None of the choices are correct.
A) analog
The ________ rate defines the number of data elements sent in one second; the ______ rate is the number of signal elements sent in one second. A) data; signal B) signal; data C) baud; bit D) none of the choices are correct
A) data; signal
As frequency increases, the period ________. A) decreases B) increases C) remains the same D) None of the choices are correct.
A) decreases
Frequency and period are ______. A) inverse of each other B) proportional to each other C) the same D) are not related
A) inverse of each other
In fiber optics, the signal is _______ waves. A) light B) radio C) infrared D) very low-frequency
A) light
Polar and bipolar encoding are types of _______ coding. A) line B) block C) scrambling D) None of the choices are correct.
A) line
Baseband transmission of a digital signal is possible only if we have a ____ channel. A) low-pass B) bandpass C) low rate D) high rate
A) low-pass
For a ______ channel, we need to use the Shannon capacity to find the maximum bit rate. A) noisy B) noiseless C) bandpass D) low-pass
A) noisy
Transmission media lie below the _______ layer. A) physical B) network C) transport D) application
A) physical
In ______ schemes, the voltage level oscillates between a positive and a negative values although it may remain at zero level between the two values. A) polar B) bipolar C) nonpolar D) None of the choices are correct.
A) polar
Block coding can help in _______ and _________ at the receiver. A) synchronization and error detection B) synchronization and attenuation C) error detection and attenuation D) error detection and distortion
A) synchronization and error detection
In ________ TDM, each input connection has an allotment in the output even if it is not sending data. A) synchronous B) statistical C) isochronous D) None of the choices are correct.
A) synchronous
In ________, the phase of the carrier is varied to represent two or more different signal elements. Both peak amplitude and frequency remain constant. A) ASK B) PSK C) FSK D) QAM
B) PSK
We can divide ____ into two different schemes: synchronous or statistical. A) FDM B) TDM C) WDM D) None of the choices are correct.
B) TDM
Which multiplexing technique is used for digital signals? A) FDM B) TDM C) WDM D) PDM
B) TDM
_____ is a digital process that allows several connections to share the high bandwidth of a link. A) FDM B) TDM C) WDM D) None of the choices are correct.
B) TDM
If the available channel is a ____ channel, we cannot send a digital signal directly to the channel. A) low-pass B) bandpass C) low rate D) high rate
B) bandpass
In _______ encoding, we use three levels: positive, zero, and negative. A) polar B) bipolar C) nonpolar D) None of the choices are correct.
B) bipolar
In QAM, both ________ of a carrier frequency are varied. A) frequency and amplitude B) phase and frequency C) amplitude and phase D) none of the choices are correct
C) amplitude and phase
AM, FM, and PM are examples of ________ conversion. A) digital-to-digital B) digital-to-analog C) analog-to-analog D) analog-to-digital
C) analog-to-analog
The _________ product defines the number of bits that can fill the link. A) bandwidth-period B) frequency-amplitude C) bandwidth-delay D) delay-amplitude
C) bandwidth-delay
How many carrier frequencies are used in BASK? A) 1 B) 2 C) 3 D) None of the choices are correct.
A) 1
How many carrier frequencies are used in BPSK? A) 1 B) 2 C) 3 D) None of the choices are correct.
A) 1
In _____ transmission, the carrier signal is modulated so that its amplitude varies with the changing amplitudes of the modulating signal. A) AM B) PM C) FM D) None of the choices are correct.
A) AM
In ________, the amplitude of the carrier signal is varied to create signal elements. Both frequency and phase remain constant. A) ASK B) PSK C) FSK D) QAM
A) ASK
_____ signals have an infinite number of values in a time interval. A) Analog B) Digital C) Either analog or digital D) None of the choices are correct.
A) Analog
How many carrier frequencies are used in BFSK? A) 1 B) 2 C) 3 D) None of the choices are correct.
B) 2
The _____ scheme uses data patterns of size 2 and encodes the 2-bit patterns as one signal element belonging to a four-level signal. A) 4B5B B) 2B1Q C) B8ZS D) None of the choices are correct.
B) 2B1Q
Quadrature amplitude modulation (QAM) is a combination of ___________. A) ASK and FSK B) ASK and PSK C) PSK and FSK D) None of the choices are correct.
B) ASK and PSK
_______ cable consists of an inner copper core and a second conducting outer sheath. A) Twisted-pair B) Coaxial C) Fiber-optic D) Shielded twisted-pair
B) Coaxial
The ______ technique expands the bandwidth of a signal by replacing each data bit with n bits using a spreading code. A) FDM B) DSSS C) FHSS D) TDM
B) DSSS
_______ signals can have only a limited number of values in a time interval. A) Analog B) Digital C) Either analog or digital D) None of the choices are correct.
B) Digital
________ is a type of transmission impairment in which the signal loses strength due to the different propagation speeds of each frequency that makes up the signal. A) Attenuation B) Distortion C) Noise D) Decibel
B) Distortion
________ is the set of techniques that allows the simultaneous transmission of multiple signals across a single data link. A) Demodulating B) Multiplexing C) Compressing D) None of the choices are correct
B) Multiplexing
In _____, the level of the voltage determines the value of the bit. A) NRZ-I B) NRZ-L C) NRZ-I or NRZ-L D) None of the choices are correct.
B) NRZ-L
The most common technique to change an analog signal to digital data is called __________. A) PAL B) PCM C) sampling D) None of the choices are correct.
B) PCM
______ finds the value of the signal amplitude for each sample; ____ finds the change from the previous sample. A) DM; PCM B) PCM; DM C) DM; CM D) None of the choices are correct.
B) PCM; DM
The idea of RZ and the idea of NRZ-I are combined into the ________ scheme. A) Manchester B) differential Manchester C) Manchester or differential Manchester D) None of the choices are correct.
B) differential Manchester
_______ data have discrete states and take discrete values. A) analog B) digital C) analog or digital D) None of the choices are correct.
B) digital
ASK, PSK, FSK, and QAM are examples of ________ conversion. A) digital-to-digital B) digital-to-analog C) analog-to-analog D) analog-to-digital
B) digital-to-analog
In a frequency-domain plot, the horizontal axis measures the ________. A) signal amplitude B) frequency C) phase D) time
B) frequency
Transmission media are usually categorized as _______. A) fixed or unfixed B) guided or unguided C) determinate or indeterminate D) metallic or nonmetallic
B) guided or unguided
For a ______ channel, the Nyquist bit rate formula defines the theoretical maximum bit rate. A) noisy B) noiseless C) bandpass D) low-pass
B) noiseless
In ________ TDM, slots are dynamically allocated to improve bandwidth efficiency. A) synchronous B) statistical C) isochronous D) None of the choices are correct.
B) statistical
Two common scrambling techniques are ________. A) NRZ and RZ B) AMI and NRZ C) B8ZS and HDB3 D) Manchester and differential Manchester
C) B8ZS and HDB3
_______ encoding has a transition at the beginning of each 0 bit. A) RZ B) Manchester C) Differential Manchester D) All the choices are correct.
C) Differential Manchester
The _______ technique uses M different carrier frequencies that are modulated by the source signal. At one moment, the sign modulates one carrier frequency; at the next moment, the signal modulates another carrier frequency. A) FDM B) DSSS C) FHSS D) TDM
C) FHSS
In _________, the frequency of the carrier signal is varied to represent data. Both peak amplitude and phase remain constant. A) ASK B) PSK C) FSK D) QAM
C) FSK
________ is the rate of change with respect to time. A) Amplitude B) Time C) Frequency D) Phase
C) Frequency
________ is a type of transmission impairment in which an outside source such as crosstalk corrupts a signal. A) Attenuation B) Distortion C) Noise D) Decibel
C) Noise
Which multiplexing technique involves signals composed of light beams? A) FDM B) TDM C) WDM D) PDM
C) WDM
____ is designed to use the high bandwidth capability of fiber-optic cable. A) FDM B) TDM C) WDM D) None of the choices are correct.
C) WDM
______ is an analog multiplexing technique to combine optical signals. A) FDM B) TDM C) WDM D) None of the choices are correct.
C) WDM
