Digital Communications Multiple Choice Questions on “Types of Processes”.
1. A stationary stochastic process has
A. Finite energy signal
B. Infinite zero signal
C. Zero energy signal
D. None of the mentioned
Answer: B
Clarification: A stationary stochastic process is an infinite energy signal and hence its fourier transform does not exist.
2. The power spectral density function of the stochastic process is
A. Real
B. Odd
C. Real & odd
D. None of the mentioned
Answer: A
Clarification: The power spectral density function of a stochastic function is real and even.
3. For a periodic function, the spectral density and auto correlation functions form
A. Fourier transform pair
B. Laplace transform pair
C. Hilbert transform pair
D. Z transform pair
Answer: A
Clarification: For a periodic function, the spectral density and auto correlation function forms fourier transform pair.
4. The capacity of a channel is given by
A. Number of digits used in coding
B. Volume of information it can take
C. Maximum rate of information transmitted
D. Bandwidth requires information
Answer: C
Clarification: The capacity of the channel is given by a maximum rate of information transmitted.
5. In a communication system, a process in which statistical averages and time averages are equal is called as
A. Stationary
B. Ergodic
C. Gaussian
D. Poisson
Answer: B
Clarification: In ergodic process statistical averages and time averages are equal.
6. A rectangular pulse of duration T is applied to a matched filter. The output of the filter is a
A. Rectangular pulse of duration T
B. Rectangular pulse of duration 2T
C. Triangular pulse
D. Sine function
Answer: C
Clarification: The output of the matched filter when a rectangular pulse of duration T is applied is a triangular pulse.
7. The line code has a zero dc component for pulse transmission of random binary data is
A. NRZ
B. RZ
C. Alternate mark inversion
D. None of the mentioned
Answer: C
Clarification: The line code has a zero dc component for pulse transmission of random binary data is alternate mark inversion.
8. The auto-correlation of white noise is
A. A delta function
B. A constant
C. Gaussian
D. None of the mentioned
Answer: A
Clarification: The auto-correlation of white noise is a delta function.
9. Ionospheric communication can take place in
A. High frequency band
B. Very high frequency band
C. Ultra high frequency band
D. Super high frequency band
Answer: A
Clarification: Ionospheric communication takes place in high frequency band.
10. Satellite communication takes place in
A. Ultra high frequency band
B. Super high frequency band
C. Ultra & Super high frequency band
D. None of the mentioned
Answer: C
Clarification: Satellite communication takes place in ultra high and super high frequency bands.
11. The weighing matrix is
A. Positive quantity
B. Inverse of covariance matrix of the input vector
C. Positive quantity & Inverse of a covariance matrix of the input vector
D. None of the mentioned
Answer: C
Clarification: W is a positive definite weighing matrix and it is inverse of covariance matrix of the input vector.
12. Non uniform tree _____ bit rate.
A. Increases
B. Decreases
C. Does not affect
D. None of the mentioned