This set of Analog Communications MCQs focuses on “Comparison Between PM and AM”.
1. Which of the following oscillator is not used in frequency modulation?
a) Colpitts Oscillator
b) Crystal Oscillator
c) Hartley Oscillator
d) Both Colpitts and Crystal Oscillator
Explanation: Crystal Oscillator uses the mechanical resonance of a vibrating crystal which is made up of piezoelectric material to create an signal with a precise frequency. It has no role in frequency modulated systems.
2. In frequency modulation, noise gets decreased if we decrease deviation.
Explanation: In frequency modulation, noise also starts decreasing if we increase deviation.
3. Which device is most commonly used for detection in radio receiver?
Explanation: In radio receivers, diode is most preferably used for detection purposes.
4. An input resistance of 20 Kῼ causes a noise voltage of 10μV. Suppose two input resistance each of 20 Kῼ are connected in parallel, then find the total noise voltage?
Explanation: Total resistance, 1⁄R = 1⁄20 + 1⁄20 = 1⁄10 so R = 10kW = 1000W. Noise voltage will be equal to (10)√10⁄20 = 8μV.
5. ________ modulator is an indirect way of generating FM.
a) Varactor FET
b) Reactance FET
d) Reactance bipolar transistor
Explanation: FM can be generated by two ways. One is direct and other is indirect way. In indirect way, there is an Armstrong method which is used to generate FM system.
6. Three point tracking is achieved by __________
a) Double conversion
b) Variable selectivity
c) Double spotting
d) Padder capacitor
Explanation: To achieve three point tracking a capacitor is connected in series with local oscillator coil. This capacitor is called padder capacitor.
7. The household radio receiver uses __________ detector.
Explanation: Household receivers generally uses envelope detector.
8. High IF in superheterodyne receiver, ____________
a) reduces adjacent channel rejection
b) improves selectivity
c) improves sensitivity
d) increases tracking problems
Explanation: In superheterodyne receiver, most of the received signals gets amplified from intermediate frequency (IF). High intermediate frequency helps in tracking problems.
9. Find the step size of a signal with peak to peak amplitude of 8V and is quantized into 40 levels?
10. If the step size of a system is 0.0721, find its quantization power?
a) 3.25 x 10-3
b) 4.33 x 10-4
c) 4.33 x 10-2
d) 3.25 x 10-1
Sanfoundry Global Education & Learning Series – Analog Communications.
To practice MCQs on all areas of Analog Communications, here is complete set of 1000+ Multiple Choice Questions and Answers.