Digital Communication Test Question Set 2

1)   In Alternate Mark Inversion (AMI) is

a. 0 is encoded as positive pulse and 1 is encoded as negative pulse
b. 0 is encoded as no pulse and 1 is encoded as negative pulse
c. 0 is encoded as negative pulse and 1 is encoded as positive pulse
d. 0 is encoded as no pulse and 1 is encoded as positive or negative pulse
Answer  Explanation  Related Ques

ANSWER: 0 is encoded as no pulse and 1 is encoded as positive or negative pulse

Explanation:
No explanation is available for this question!


2)   Advantages of using AMI

a. Needs least power as due to opposite polarity
b. Prevents build-up of DC
c. May be used for longer distance
d. All of the above
Answer  Explanation  Related Ques

ANSWER: All of the above

Explanation:
No explanation is available for this question!


3)   The interference caused by the adjacent pulses in digital transmission is called

a. Inter symbol interference
b. White noise
c. Image frequency interference
d. Transit time noise
Answer  Explanation  Related Ques

ANSWER: Inter symbol interference

Explanation:
No explanation is available for this question!


4)   Eye pattern is

a. Is used to study ISI
b. May be seen on CRO
c. Resembles the shape of human eye
d. All of the above
Answer  Explanation  Related Ques

ANSWER: All of the above

Explanation:
No explanation is available for this question!


5)   The time interval over which the received signal may be sampled without error may be explained by

a. Width of eye opening of eye pattern
b. Rate of closure of eye of eye pattern
c. Height of the eye opening of eye pattern
d. All of the above
Answer  Explanation  Related Ques

ANSWER: Width of eye opening of eye pattern

Explanation:
No explanation is available for this question!


6)   For a noise to be white Gaussian noise, the optimum filter is known as

a. Low pass filter
b. Base band filter
c. Matched filter
d. Bessel filter
Answer  Explanation  Related Ques

ANSWER: Matched filter

Explanation:
No explanation is available for this question!


7)   Matched filters are used

a. For maximizing signal to noise ratio
b. For signal detection
c. In radar
d. All of the above
Answer  Explanation  Related Ques

ANSWER: All of the above

Explanation:
No explanation is available for this question!


8)   The number of bits of data transmitted per second is called

a. Data signaling rate
b. Modulation rate
c. Coding
d. None of the above
Answer  Explanation  Related Ques

ANSWER: Data signaling rate

Explanation:
No explanation is available for this question!


9)   Pulse shaping is done

a. to control Inter Symbol Interference
b. by limiting the bandwidth of transmission
c. after line coding and modulation of signal
d. All of the above
Answer  Explanation  Related Ques

ANSWER: All of the above

Explanation:
No explanation is available for this question!


10)   The criterion used for pulse shaping to avoid ISI is

a. Nyquist criterion
b. Quantization
c. Sample and hold
d. PLL
Answer  Explanation  Related Ques

ANSWER: Nyquist criterion

Explanation:
No explanation is available for this question!


11)   The filter used for pulse shaping is

a. Raised - cosine filter
b. Sinc shaped filter
c. Gaussian filter
d. All of the above
Answer  Explanation  Related Ques

ANSWER: All of the above

Explanation:
No explanation is available for this question!


12)   Roll - off factor is defined as

a. The bandwidth occupied beyond the Nyquist Bandwidth of the filter
b. The performance of the filter or device
c. Aliasing effect
d. None of the above
Answer  Explanation  Related Ques

ANSWER: The bandwidth occupied beyond the Nyquist Bandwidth of the filter

Explanation:
No explanation is available for this question!


13)   Nyquist criterion helps in

a. Transmitting the signal without ISI
b. Reduction in transmission bandwidth
c. Increase in transmission bandwidth
d. Both a and b
Answer  Explanation  Related Ques

ANSWER: Both a and b

Explanation:
No explanation is available for this question!


14)   The Nyquist theorem is

a. Relates the conditions in time domain and frequency domain
b. Helps in quantization
c. Limits the bandwidth requirement
d. Both a and c
Answer  Explanation  Related Ques

ANSWER: Both a and c

Explanation:
No explanation is available for this question!


15)   The difficulty in achieving the Nyquist criterion for system design is

a. There are abrupt transitions obtained at edges of the bands
b. Bandwidth criterion is not easily achieved
c. Filters are not available
d. None of the above
Answer  Explanation  Related Ques

ANSWER: There are abrupt transitions obtained at edges of the bands

Explanation:
No explanation is available for this question!


16)   Equalization in digital communication

a. Reduces inter symbol interference
b. Removes distortion caused due to channel
c. Is done using linear filters
d. All of the above
Answer  Explanation  Related Ques

ANSWER: All of the above

Explanation:
No explanation is available for this question!


17)   Zero forced equalizers are used for

a. Reducing ISI to zero
b. Sampling
c. Quantization
d. None of the above
Answer  Explanation  Related Ques

ANSWER: Reducing ISI to zero

Explanation:
No explanation is available for this question!


18)   The transmission bandwidth of the raised cosine spectrum is given by

a. Bt = 2w(1 + α)
b. Bt = w(1 + α)
c. Bt = 2w(1 + 2α)
d. Bt = 2w(2 + α)
Answer  Explanation  Related Ques

ANSWER: Bt = 2w(1 + α)

Explanation:
No explanation is available for this question!


19)   The preferred orthogonalization process for its numerical stability is

a. Gram- Schmidt process
b. House holder transformation
c. Optimization
d. All of the above
Answer  Explanation  Related Ques

ANSWER: House holder transformation

Explanation:
No explanation is available for this question!


20)   For two vectors to be orthonormal, the vectors are also said to be orthogonal. The reverse of the same

a. Is true
b. Is not true
c. Is not predictable
d. None of the above
Answer  Explanation  Related Ques

ANSWER: Is not true

Explanation:
No explanation is available for this question!


21)   Orthonormal set is a set of all vectors that are

a. Mutually orthonormal and are of unit length
b. Mutually orthonormal and of null length
c. Both a & b
d. None of the above
Answer  Explanation  Related Ques

ANSWER: Mutually orthonormal and are of unit length

Explanation:
No explanation is available for this question!


22)   In On-Off keying, the carrier signal is transmitted with signal value '1' and '0' indicates

a. No carrier
b. Half the carrier amplitude
c. Amplitude of modulating signal
d. None of the above
Answer  Explanation  Related Ques

ANSWER: No carrier

Explanation:
No explanation is available for this question!


23)   ASK modulated signal has the bandwidth

a. Same as the bandwidth of baseband signal
b. Half the bandwidth of baseband signal
c. Double the bandwidth of baseband signal
d. None of the above
Answer  Explanation  Related Ques

ANSWER: Same as the bandwidth of baseband signal

Explanation:
No explanation is available for this question!


24)   Coherent detection of binary ASK signal requires

a. Phase synchronization
b. Timing synchronization
c. Amplitude synchronization
d. Both a and b
Answer  Explanation  Related Ques

ANSWER: Both a and b

Explanation:
No explanation is available for this question!


25)   The probability of error of DPSK is ______________ than that of BPSK.

a. Higher
b. Lower
c. Same
d. Not predictable
Answer  Explanation  Related Ques

ANSWER: Higher

Explanation:
No explanation is available for this question!


26)   In Binary Phase Shift Keying system, the binary symbols 1 and 0 are represented by carrier with phase shift of

a. Π/2
b. Π
c.
d. 0
Answer  Explanation  Related Ques

ANSWER: Π

Explanation:
No explanation is available for this question!


27)   BPSK system modulates at the rate of

a. 1 bit/ symbol
b. 2 bit/ symbol
c. 4 bit/ symbol
d. None of the above
Answer  Explanation  Related Ques

ANSWER: 1 bit/ symbol

Explanation:
No explanation is available for this question!


28)   The BPSK signal has +V volts and -V volts respectively to represent

a. 1 and 0 logic levels
b. 11 and 00 logic levels
c. 10 and 01 logic levels
d. 00 and 11 logic levels
Answer  Explanation  Related Ques

ANSWER: 1 and 0 logic levels

Explanation:
No explanation is available for this question!


29)   The binary waveform used to generate BPSK signal is encoded in

a. Bipolar NRZ format
b. Manchester coding
c. Differential coding
d. None of the above
Answer  Explanation  Related Ques

ANSWER: Bipolar NRZ format

Explanation:
No explanation is available for this question!


30)   The bandwidth of BFSK is ______________ than BPSK.

a. Lower
b. Same
c. Higher
d. Not predictable
Answer  Explanation  Related Ques

ANSWER: Higher

Explanation:
No explanation is available for this question!


31)   In Binary FSK, mark and space respectively represent

a. 1 and 0
b. 0 and 1
c. 11 and 00
d. 00 and 11
Answer  Explanation  Related Ques

ANSWER: 1 and 0

Explanation:
No explanation is available for this question!


32)   The frequency shifts in the BFSK usually lies in the range

a. 50 to 1000 Hz
b. 100 to 2000 Hz
c. 200 to 500 Hz
d. 500 to 10 Hz
Answer  Explanation  Related Ques

ANSWER: 50 to 1000 Hz

Explanation:
No explanation is available for this question!


33)   The spectrum of BFSK may be viewed as the sum of

a. Two ASK spectra
b. Two PSK spectra
c. Two FSK spectra
d. None of the above
Answer  Explanation  Related Ques

ANSWER: Two ASK spectra

Explanation:
No explanation is available for this question!


34)   The maximum bandwidth is occupied by

a. ASK
b. BPSK
c. FSK
d. None of the above
Answer  Explanation  Related Ques

ANSWER: FSK

Explanation:
No explanation is available for this question!


35)   QPSK is a modulation scheme where each symbol consists of

a. 4 bits
b. 2 bits
c. 1 bits
d. M number of bits, depending upon the requirement
Answer  Explanation  Related Ques

ANSWER: 2 bits

Explanation:
No explanation is available for this question!


36)   The data rate of QPSK is ___________ of BPSK.

a. Thrice
b. Four times
c. Twice
d. Same
Answer  Explanation  Related Ques

ANSWER: Twice

Explanation:
No explanation is available for this question!


37)   QPSK system uses a phase shift of

a. Π
b. Π/2
c. Π/4
d.
Answer  Explanation  Related Ques

ANSWER: Π/2

Explanation:
No explanation is available for this question!


38)   Minimum shift keying is similar to

a. Continuous phase frequency shift keying
b. Binary phase shift keying
c. Binary frequency shift keying
d. QPSK
Answer  Explanation  Related Ques

ANSWER: Continuous phase frequency shift keying

Explanation:
No explanation is available for this question!


39)   In MSK, the difference between the higher and lower frequency is

a. Same as the bit rate
b. Half of the bit rate
c. Twice of the bit rate
d. Four time the bit rate
Answer  Explanation  Related Ques

ANSWER: Half of the bit rate

Explanation:
No explanation is available for this question!


40)   The technique that may be used to reduce the side band power is

a. MSK
b. BPSK
c. Gaussian minimum shift keying
d. BFSK
Answer  Explanation  Related Ques

ANSWER: Gaussian minimum shift keying

Explanation:
No explanation is available for this question!