# Digital Communications Questions and Answers – Types of Processes

This set of Digital Communications Multiple Choice Questions & Answers (MCQs) focuses on “Types of Processes”.

**1. 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

**Explanation:** W is a positive definite weighing matrix that is the inverse of the input vector’s covariance matrix.

**2. Non uniform tree _____ bit rate.**

**a) Increases**

b) Decreases

c) Does not affect

d) None of the mentioned

**Explanation:** Non uniform tree for binary search increases the bit rate.

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

a) Rational

**b) Irrational**

c) Equal

d) None of the mentioned

**Explanation:** Two clock with rates T1 and T2 are incommensurate if its ratio is irrational.

**4. Possible timing error detection methods areQuestions and Answers**

a) Early late

b) Zero crossing

**c) Early late & Zero crossing**

d) None of the mentioned

**Explanation:** Early late timing error detection and zero crossing timing error detection are two methods for detecting timing errors.

**5. 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

**Explanation:** Twisted copper wire at 1KHz have low power loss.

**6. Voltage generated by lightning is an example for**

**a) Energy signal**

b) Power signal

c) Energy & Power signal

d) None of the mentioned

**Explanation:** Voltage generated by lightning is an example for energy signal and it has very high power.

**7. A stationary stochastic process has**

a) Finite energy signal

**b) Infinite zero signal**

c) Zero energy signal

d) None of the mentioned

**Explanation:** Because a stationary stochastic process has an infinite energy signal, it has no fourier transform.

**8. The power spectral density function of the stochastic process is**

**a) Real**

b) Odd

c) Real & odd

d) None of the mentioned

**Explanation:** The power spectral density function of a stochastic function is real and even.

**9. 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

**Explanation:** The spectral density and auto correlation function constitute a fourier transform pair for a periodic function.

**10. 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

**Explanation**: The maximum rate of information transmitted determines the channel’s capacity.

**11. 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

**Explanation:** In ergodic process statistical averages and time averages are equal.

**12. 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

**Explanation:** When a rectangular pulse of time T is applied to the matching filter, the result is a triangular pulse.

**13. 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

**Explanation:** Alternate mark inversion is a line code with a zero dc component for pulse transmission of random binary data.

**14. The auto-correlation of white noise is**

**a) A delta function**

b) A constant

c) Gaussian

d) None of the mentioned

**Explanation:** The auto-correlation of white noise is a delta function.

**15. 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

**Explanation:** Ionospheric communication takes place in high frequency band.

**16. 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

**Explanation:** The extremely high and super high frequency bands are used for satellite communication.

A process is essentially a running software. The execution of a process must proceed in a logical order. To put it another way, we write our computer programmes in a text file, and when we run them, they turn into a process that completes all of the duties specified in the programme. W is a positive definite weighing matrix that is the inverse of the input vector’s covariance matrix. Two approaches for identifying timing errors are early late timing error detection and zero crossing timing error detection.