laboursonline – MCQs, Mock Tests | Computer Hardware and Networking NETWORKING /PHYSICAL LAYER SET 2

_______ encoding has a transition at the beginning of each 0 bit.

1. RZ
2. Manchester
3. Differential Manchester
4. All of the above

✅ Correct Answer: 3

PCM is an example of _______ conversion.

1. digital-to-digital
2. digital-to-analog
3. analog-to-analog
4. analog-to-digital

✅ Correct Answer: 4

If the frequency spectrum of a signal has a bandwidth of 500 Hz with the highest frequency at 600 Hz, what should be the sampling rate, according to the Nyquist theorem?

1. 200 samples/s
2. 500 samples/s
3. 1000 samples/s
4. 1200 samples/s

✅ Correct Answer: 4

The Nyquist theorem specifies the minimum sampling rate to be_______.

1. equal to the lowest frequency of a signal
2. equal to the highest frequency of a signal
3. twice the bandwidth of a signal
4. twice the highest frequency of a signal

✅ Correct Answer: 4

Which of the following encoding methods does not provide for synchronization?

1. NRZ-L
2. RZ
3. NRZ-I
4. Manchester

✅ Correct Answer: 1

Which encoding method uses alternating positive and negative values for 1s?

1. NRZ-I
2. RZ
3. Manchester
4. AMI

✅ Correct Answer: 4

Which quantization level results in a more faithful reproduction of the signal?

1. 2
2. 8
3. 16
4. 32

✅ Correct Answer: 4

Block coding can help in _______ at the receiver.

1. Synchronization
2. Error detection
3. Attenuation
4. both (a) and (b)

✅ Correct Answer: 4

In _______ transmission, a start bit and a stop bit frame a character byte.

1. asynchronous serial
2. synchronous serial
3. parallel
4. (a) and (b)

✅ Correct Answer: 1

In asynchronous transmission, the gap time between bytes is _______.

1. fixed
2. variable
3. a function of the data rate
4. zero

✅ Correct Answer: 2

___________ conversion involves three techniques: line coding, block coding, and scrambling.

1. Analog-to-digital
2. Digital-to-analog
3. Analog-to-analog
4. Digital-to-digital

✅ Correct Answer: 4

________ is the process of converting digital data to a digital signal.

1. Block coding
2. Line coding
3. Scrambling
4. None of the above

✅ Correct Answer: 2

_____ provides redundancy to ensure synchronization and inherent error detection.

1. Block coding
2. Line coding
3. Scrambling
4. None of the above

✅ Correct Answer: 1

______ is normally referred to as mB/nB coding; it replaces each m-bit group with an n-bit group.

1. Block coding
2. Line coding
3. Scrambling
4. None of the above

✅ Correct Answer: 1

_ provides synchronization without increasing the number of bits.

1. Scrambling encoding
2. Line coding
3. Block coding
4. None of the above

✅ Correct Answer: 1

Two common scrambling techniques are ________.

1. NRZ and RZ
2. AMI and NRZ
3. B8ZS and HDB3
4. Manchester and differential Manchester

✅ Correct Answer: 3

The most common technique to change an analog signal to digital data is called __________.

1. PAL
2. PCM
3. sampling
4. none of the above

✅ Correct Answer: 2

The first step in PCM is ________.

1. quantization
2. modulation
3. sampling
4. none of the above

✅ Correct Answer: 3

There are three sampling methods: __________.

1. quantized, sampled, and ideal
2. ideal, sampled, and flat-top
3. ideal, natural, and flat-top
4. none of the above

✅ Correct Answer: 3

____ finds the value of the signal amplitude for each sample; ____ finds the change from the previous sample.

1. DM; PCM
2. PCM; DM
3. DM; CM
4. none of the above

✅ Correct Answer: 2

While there is (are) only _____ way(s) to send parallel data, there is (are) three subclass(es) of serial transmission.

1. one; two
2. two; three
3. one; three
4. none of the above

✅ Correct Answer: 3

In ______ transmission, we send 1 start bit (0) at the beginning and 1 or more stop bits (1s) at the end of each byte.

1. synchronous
2. asynchronous
3. isochronous
4. none of the above

✅ Correct Answer: 2

In _________ transmission, we send bits one after another without start or stop bits or gaps. It is the responsibility of the receiver to group the bits.

1. synchronous
2. asynchronous
3. isochronous
4. None of the above

✅ Correct Answer: 1

The ________ mode provides synchronization for the entire stream of bits must. In other words, it guarantees that the data arrive at a fixed rate.

1. synchronous
2. asynchronous
3. isochronous
4. none of the above

✅ Correct Answer: 3

A _________ digital signal includes timing information in the data being transmitted.

1. self-synchronizing
2. self-modulated
3. self-transmitted
4. none of the above

✅ Correct Answer: 1

In decoding a digital signal, the receiver calculates a running average of the received signal power, called the _______.

1. baseline
2. base
3. line
4. none of the above

✅ Correct Answer: 1

The ________ rate defines the number of data elements sent in 1s; the ______ rate is the number of signal elements sent in 1s.

1. data; signal
2. signal; data
3. baud; bit
4. none of the above

✅ Correct Answer: 1

The signal rate is sometimes called the ____ rate.

1. baud
2. bit
3. signal
4. None of the above

✅ Correct Answer: 1

The data rate is sometimes called the ___ rate.

1. baud
2. bit
3. signal
4. None of the above

✅ Correct Answer: 2

In a _____ scheme, all the signal levels are on one side of the time axis, either above or below.

1. polar
2. bipolar
3. unipolar
4. All of the above

✅ Correct Answer: 3

In ______ schemes, the voltages are on the both sides of the time axis. For example, the voltage level for 0 can be positive and the voltage level for 1 can be negative.

1. polar
2. bipolar
3. unipolar
4. All of the above

✅ Correct Answer: 1

In _____, the level of the voltage determines the value of the bit.

1. NRZ-I
2. NRZ-L
3. both (a) and (b)
4. neither (a) nor (b)

✅ Correct Answer: 2

In ______, the change or lack of change in the level of the voltage determines the value of the bit.

1. NRZ-I
2. NRZ-L
3. both (a) and (b)
4. neither (a) nor (b)

✅ Correct Answer: 1

The idea of RZ and the idea of NRZ-L are combined into the ________ scheme.

1. Manchester
2. differential Manchester
3. both (a) and (b)
4. neither (a) nor (b)

✅ Correct Answer: 1

The idea of RZ and the idea of NRZ-I are combined into the ________ scheme.

1. Manchester
2. differential Manchester
3. both (a) and (b)
4. neither (a) nor (b)

✅ Correct Answer: 2

In _______ encoding, the duration of the bit is divided into two halves. The voltage remains at one level during the first half and moves to the other level in the second half. The transition at the middle of the bit provides synchronization.

1. Manchester
2. differential Manchester
3. both (a) and (b)
4. neither (a) nor (b)

✅ Correct Answer: 3

In ___________ there is always a transition at the middle of the bit, but the bit values are determined at the beginning of the bit. If the next bit is 0, there is a transition; if the next bit is 1, there is none.

1. Manchester
2. differential Manchester
3. both (a) and (b)
4. neither (a) nor (b)

✅ Correct Answer: 2

In Manchester and differential Manchester encoding, the transition at the middle of the bit is used for __________.

1. bit transfer
2. baud transfer
3. synchronization
4. None of the above

✅ Correct Answer: 3

The minimum bandwidth of Manchester and differential Manchester is ____ that of NRZ.

1. the same as
2. twice
3. thrice
4. None of the above

✅ Correct Answer: 2

In _______encoding, we use three levels: positive, zero, and negative.

1. unipolar
2. bipolar
3. polar
4. none of the above

✅ Correct Answer: 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.

1. 4B5B
2. 2B1Q
3. MLT-3
4. none of the above

✅ Correct Answer: 2

The ______ scheme uses three levels (+V, 0, and -V) and three transition rules to move between the levels.

1. 4B5B
2. 2B1Q
3. MLT-3
4. none of the above

✅ Correct Answer: 3

_____ substitutes eight consecutive zeros with 000VB0VB. a.

1. B4B8
2. HDB3
3. B8ZS
4. None of these

✅ Correct Answer: 3

______ substitutes four consecutive zeros with 000V or B00V.

1. B4B8
2. HDB3
3. B8ZSf
4. None of these

✅ Correct Answer: 2

ASK, PSK, FSK, and QAM are examples of ________ conversion.

1. digital-to-digital
2. digital-to-analog
3. analog-to-analog
4. analog-to-digital

✅ Correct Answer: 2

AM and FM are examples of ________ conversion.

1. digital-to-digital
2. digital-to-analog
3. analog-to-analog
4. analog-to-digital

✅ Correct Answer: 3

In QAM, both ________ of a carrier frequency are varied.

1. frequency and amplitude
2. phase and frequency
3. amplitude and phase
4. none of the above

✅ Correct Answer: 3

If the baud rate is 400 for a QPSK signal, the bit rate is ________ bps.

1. 100
2. 400
3. 800
4. 1600

✅ Correct Answer: 3

If the bit rate for an ASK signal is 1200 bps, the baud rate is ________.

1. 300
2. 400
3. 600
4. 1200

✅ Correct Answer: 4

If the bit rate for an FSK signal is 1200 bps, the baud rate is ________.

1. 300
2. 400
3. 600
4. 1200

✅ Correct Answer: 4