This set of Analog Communications Multiple Choice Questions & Answers (MCQs) focuses on “Methods of Reducing Distortion”.
1. Quantization error occurs in ________
a) Time Division Multiplexing
b) Frequency Division Multiplexing
c) Pulse Code Modulation
d) Pulse Width Modulation
Explanation: The difference between an input value and its quantized value is called quantization error or we can also see it as that when an analog number is not converted into an exact digital number. It takes place in pulse code modulation (PCM).
2. If power transmitted is 90kW, what is the field at a distance of 45km?
3. Find the number of pulses, if the number of quantization level is 32 in PCM?
Explanation: 2n = 32, so n = 5.
4. Which transistor amplifier is most commonly used?
a) Common Base
b) Common Emitter
c) Common Collector
d) None of these
Explanation: Common Emitter is most widely used because it has high power gain and voltage gain. Moreover it also provides maximum transconductance for a given load.
5. A device uses a 8 bit word then the maximum number of words it can transmit is ________
Explanation: Number of words it can transmit is 28 = 256.
6. Peak voltage of a carrier is 8kV, each sideband has an amplitude of 800V. Find its modulation index?
Explanation: (mVc)/2 = 800. By substituting values, we have mX8000/2 = 800. So, m = 0.2.
7. What do you understand by the term Cross talk?
a) generation of closely lying sidebands
b) a method of increasing bandwidth
c) a method of decreasing bandwidth by converting DSB-SC signal to SSB-SC
d) disturbance caused in nearby circuit due to transmitted signal
Explanation: Disturbances caused in nearby circuit due to some reasons are called cross talk. It is generally caused by undesired coupling.
8. AM waves is represented by Et cos ωc t. What does Et denotes?
b) carrier signal
c) modulating signal
Explanation: AM wave is represented by (A + xt) cosωc t or Et cosωc t, where xt is modulating signal, A is amplitude and Et is amplitude of AM wave.
9. Wireless communication takes place through ________
a) EM waves
c) Optical Fibres
d) Magnetic waves
Explanation: Wireless communication takes place through electromagnetic waves. Waves are transmitted through antenna.
10. Which modulation technique uses minimum bandwidth?
Explanation: SSB uses least bandwidth since it has only one sideband whereas DSB-SC has two sidebands which increases its bandwidth.
Sanfoundry Global Education & Learning Series – Analog Communications.
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