Analog Communications Questions and Answers – RF Mixing

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This set of Analog Communications Multiple Choice Questions & Answers (MCQs) focuses on “RF Mixing”.

1. For a periodic function, the spectral density and auto-correlation functions are ________
a) Laplace transform pair
b) Fourier transform pair
c) Gauss transform pair
d) Z-transform pair
View Answer

Answer: b
Explanation: Fourier transform breaks a function into an alternate representation, characterized by sine and cosines. If a function is periodic, the spectral density and auto-correlation functions are Fourier transform pair.

2. Spectral density express ________
a) Average voltage
b) Average power in a waveform as a function of frequency
c) Average noise voltage
d) Average channel capacity
View Answer

Answer: b
Explanation: Power Spectral Density (PSD) of any signal describes the power present in signal as a function of frequency.

3. For a Gaussian process, auto correction also implies _________
a) Statistical dependance
b) Statistical independence
c) Statistical distribution
d) Ergodic process
View Answer

Answer: b
Explanation: For a Gaussian process, auto correction implies statistical independence. It is basically a stochastic process.
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4. What will be the value of modulation if we want maximum undistorted transmitted power?
a) 0
b) 1
c) 0.2
d) 0.5
View Answer

Answer: b
Explanation: For getting maximum undistorted power in any modulated system, then the modulation index of that system should be 1. Thus, the signal should be 100% modulated.

5. For providing two or more voice circuits on the same carrier, we can use _________
a) SSB
b) ISB systems
c) DSB-SC
d) VSB
View Answer

Answer: b
Explanation: ISB systems refers to Independent Sideband Mode and is used to provide the same carrier to two or more voice circuits.

6. The output stage of television transmitters is most likely to be a __________
a) Grid modulated class C amplifier
b) Grid modulated class A amplifier
c) Plate modulated class C amplifier
d) Plate modulated class A amplifier
View Answer

Answer: a
Explanation: The output stage of television transmitters are basically class C amplifiers. It is grid modulated.

7. Modulation is used to separate differing transmission.
a) True
b) False
View Answer

Answer: a
Explanation: Modulation is the property of varying one or more properties, like amplitude, frequency or phase of a periodic waveform, known as a carrier wave, with respect to the amplitude of the wave to be transmitted. It is used for separating different transmission.
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8. A function f(x) is odd, when?
a) f(x) = -f(x)
b) f(x) = f(-x)
c) f(x) = -f(x)f(-x)
d) f(x) = f(x)f(-x)
View Answer

Answer: a
Explanation: Geometrically a function f(x) is even, if plot of the function is symmetric over y-axis. Algebraically, for any function f(x) to be even, f(x) = f(-x).
While for a function f(x) to be odd, f(x) = -f(-x).

Sanfoundry Global Education & Learning Series – Analog Communications.

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To practice all areas of Analog Communications, here is complete set of 1000+ Multiple Choice Questions and Answers.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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