This set of Digital Communications Multiple Choice Questions & Answers (MCQs) focuses 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

2. The power spectral density function of the stochastic process is**a) Real**

b) Odd

c) Real & odd

d) None of the mentioned

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

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

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

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

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

8. The auto-correlation of white noise is**a) A delta function**

b) A constant

c) Gaussian

d) None of the mentioned

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

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

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

12. Non uniform tree _____ bit rate.**a) Increases**

b) Decreases

c) Does not affect

d) None of the mentioned

13. Two clock with rates T1 and T2 are incommensurate if its ratio is

a) Rational**b) Irrational**

c) Equal

d) None of the mentioned

14. Possible timing error detection methods are

a) Early late

b) Zero crossing**c) Early late & Zero crossing**

d) None of the mentioned

15. Which has minimum power loss during transmission?**a) Twisted Copper cable at 1KHz**

b) Optical fiber

c) Twisted copper cable at 100KHz

d) Wave guide

16. Voltage generated by lightning is an example for**a) Energy signal**

b) Power signal

c) Energy & Power signal

d) None of the mentioned