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Digital Communications MCQs set-1
50 questions · Test your knowledge
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Digital Communications MCQs set-1
1
Which circuit is called as regenerative repeaters?
A
Analog circuits
B
Digital circuits
C
Amplifiers
D
A/D converters
2
What are the advantages of digital circuits?
A
Less noise
B
Less interference
C
More flexible
D
All of the mentioned
3
How many bytes does a gigabyte have?
A
1 million bytes
B
10 million bytes
C
1 billion bytes
D
10 billion bytes
4
What is the ASCII value of space?
A
32
B
48
C
96
D
65
5
Which block or device does the data compression?
A
Channel encoder
B
Source encoder
C
Modulator
D
None of the mentioned
6
What is the code rate?
A
k/n
B
n/k
C
All of the mentioned
D
None of the mentioned
7
Pulse shaping is done by which block or system?
A
Encoder
B
Baseband modulator
C
Pulse code modulator
D
Demodulator
8
Equalizer is used for?
A
Filtering
B
Diminish distortion
C
All of the mentioned
D
None of the mentioned
9
Source coding block is used for?
A
Compressing
B
Digitizing
C
A/D conversion
D
All of the mentioned
10
Which measurement considers phase as an important parameter?
A
Coherent
B
Non-coherent
C
All of the mentioned
D
None of the mentioned
11
What is the period of a signal x(t)?
A
T
B
2T
C
T/2
D
None of the mentioned
12
Which of the given signals are periodic?
A
x(t) = 4 cos(5Ï€t)
B
x(t) = u(t) – 1/2
C
x(t) = 4u(t) + 2sin(3t)
D
x[n] = 2sin(3n)
13
Check whether the signal is periodic or not? x(t) = cos(4t) + 2sin(8t)
A
Periodic with period π/2
B
Periodic with period 2
C
Periodic with period 2/Ï€
D
Not periodic
14
Find the periodicity of the following signal. x(t)=cos((2Ï€/7)t)sin((3Ï€/5)t)
A
30
B
7
C
35
D
5/3
15
Find the fundamental period of 1+sin^2 (3Ï€/5)n.
A
10/3
B
5
C
3Ï€/5
D
None of the mentioned
16
Which signal is called as energy signal?
A
Finite energy and zero power
B
Finite energy and non-zero power
C
Infinite energy and zero power
D
Infinite energy and non-zero power
17
Which signal is said to be power signal?
A
Infinite power and zero energy
B
Infinite power and non-zero energy
C
Finite power and infinite energy
D
Finite power and zero energy
18
Continuous Impulse signal is a power or energy signal?
A
Power signal
B
Energy signal
C
Both power and energy
D
Neither power nor energy signal
19
Discrete impulse signal is a power or energy signal?
A
Power signal
B
Energy signal
C
Both power and energy signal
D
Neither power or energy signal
20
A unit impulse function has?
A
Large amplitude
B
Zero pulse width
C
Unity weight
D
All of the mentioned
21
Power spectral density function is a?
A
Real and even function
B
Non negative function
C
Periodic
D
All of the mentioned
22
Energy spectral density defines
A
Signal energy per unit area
B
Signal energy per unit bandwidth
C
Signal power per unit area
D
Signal power per unit bandwidth
23
Power spectrum describes distribution of _________ under frequency domain.
A
Mean
B
Variance
C
Gaussian
D
None of the mentioned
24
How can power spectral density of non periodic signal be calculated?
A
By integrating
B
By truncating
C
By converting to periodic
D
None of the mentioned
25
What is Wiener-Khinchin theorem?
A
Spectral density and auto-covariance makes a fourier transform pair
B
Spectral density and auto-correlatioon makes a fourier tranform pair
C
Spectral density and variance makes a fourier tranform pair
D
None of the mentioned
26
According to Parseval’s theorem the energy spectral density curve is equal to?
A
Area under magnitude of the signal
B
Area under square of the magnitude of the signal
C
Area under square root of magnitude of the signal
D
None of the mentioned
27
Spectogram is the graph plotted against?
A
Frequency domain
B
Time domain
C
Frequency & Time domain
D
None of the mentioned
28
Autocorrelation is a function which matches
A
Two same signals
B
Two different signal
C
One signal with its delayed version
D
None of the mentioned
29
Autocorrelation is a function of
A
Time
B
Frequency
C
Time difference
D
Frequency difference
30
Autocorrelation is maximum at _______
A
Unity
B
Origin
C
Infinite point
D
None of the mentioned
31
Autocorrelation function of periodic signal is equal to _______
A
Energy of the signal
B
Power of the signal
C
Its area in frequency domain
D
None of the mentioned
32
Autocorrelation is a _______ function.
A
Real and even
B
Real and odd
C
Complex and even
D
Complex and odd
33
Autocorrelation function of white noise will have?
A
Strong peak
B
Infinite peak
C
Weak peak
D
None of the mentioned
34
Random variables give relationship between _____
A
Two random events
B
Probability of occurence of two random events
C
Random event and a real number
D
Random event and its probability of occurrence
35
The distribution function of random variable is
A
P(X less than or equal to x)
B
P(X greater than or equal to x)
C
P(X less than x)
D
P(X greater than x)
36
The distribution function of -(infinity) and (infinity) is _____
A
0 and 1
B
1 and 0
C
Both 0
D
Both 1
37
The value of the probability density function of random variable is
A
Positive function
B
Negative function
C
Zero
D
One
38
Which gives the measure of randomness of the random variable?
A
Mean
B
Variance
C
Standard variance
D
Pdf
39
Random process is a function of ______
A
Random event and time
B
Random event and frequency
C
Random event and real number
D
None of the mentioned
40
A random process is called as stationary in strict sense if
A
Its statistics vary with shift in time origin
B
Its statistics does not vary with shift in time origin
C
Its autocorrelation vary with shift in time
D
Its autocorrelation does not vary with shift in time
41
For a stationary process, autocorrelation function depends on
A
Time
B
Time difference
C
Does not depend on time
D
None of the mentioned
42
The autocorrelation function is maximum at
A
Origin
B
Infinity
C
Origin & Infinity
D
None of the mentioned
43
White noise has _____ mean and ______ variance.
A
Zero and zero
B
Finite and zero
C
Zero and finite
D
One and zero
44
The process of data conversion along with formatting the data is called as ______
A
Formatting
B
Modulation
C
Source coding
D
Amplifying
45
Formatting is the process which includes
A
Pulse code modulation
B
Sampling
C
Quantization
D
All of the mentioned
46
Analog information is converted to digital data using
A
Sampling
B
Quantization
C
Coding
D
All of the mentioned
47
The process that transforms text into binary digits is called as _______
A
Binary coding
B
Data coding
C
Character coding
D
Sampling
48
For the number of bits, k=1 and number of symbols, M=2 the system is called as
A
Unary
B
Binary
C
Quarternary
D
None of the mentioned
49
Perform the bit stream partitioning and find the 8-ary waveform for the word ‘THINK’.
A
1204443464
B
4643444021
C
1240443464
D
none of the mentioned
50
Find the 32-ary waveform for the word ‘THINK’.
A
514172520
B
202517415
C
541172520
D
None of the mentioned
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