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51.	What is the percentage of modulation if the modulating signal is of 7.5V and carrier is of 9V?(a) 100(b) 91(c) 83.33(d) 0I had been asked this question during an online interview.This question is from Amplitude Modulation and Modulation Index topic in portion Amplitude & Frequency Modulation of Avionics
Answer» The correct choice is (c) 83.33 For EXPLANATION: MODULATION INDEX m = ^Vm⁄Vc = ^7.5⁄9* 100 = 83.33.

52.	When does over-modulation occur?(a) Modulating signal voltage < Carrier voltage(b) Modulating signal voltage > Carrier voltage(c) Modulating signal voltage = Carrier voltage(d) Modulating signal voltage =0The question was asked in an online quiz.This intriguing question originated from Amplitude Modulation and Modulation Index topic in portion Amplitude & Frequency Modulation of Avionics
Answer» The correct OPTION is (b) Modulating signal voltage > Carrier voltage The best I can explain: Over-modulation is a condition in which the modulating signal voltage is much greater than the carrier voltage. The RECEIVED signal will produce an output waveform in the shape of the envelope, WHOSE negative PEAKS have been clipped off.

53.	The ratio between the modulating signal voltage and the carrier voltage is called?(a) Amplitude modulation(b) Modulation frequency(c) Modulation index(d) Ratio of modulationI have been asked this question in an online interview.Question is taken from Amplitude Modulation and Modulation Index topic in portion Amplitude & Frequency Modulation of Avionics
Answer» CORRECT choice is (c) Modulation index For EXPLANATION: For undistorted modulation to occur, the voltage of modulating signal Vm MUST be less than the carrier voltage Vc. Therefore, the relationship between the AMPLITUDE of the modulating signal and the amplitude of the carrier signal is important. This relationship, known as the modulation index m, is the ratio m = ^Vm⁄Vc.

54.	What is the circuit used for producing AM called?(a) Modulator(b) Transmitter(c) Receiver(d) DuplexerThe question was posed to me during an interview for a job.This interesting question is from Amplitude Modulation and Modulation Index in section Amplitude & Frequency Modulation of Avionics
Answer» The correct option is (a) Modulator Explanation: The circuit used for PRODUCING AM is called a modulator. It has TWO inputs, the carrier and the modulating signal, and the resulting output is the MODULATED signal. Amplitude MODULATORS compute the product of the carrier and modulating signals.

55.	What is the effect of distortion?(a) Total information loss(b) Error information(c) Attenuated information(d) Amplified informationI got this question in unit test.My doubt stems from Amplitude Modulation and Modulation Index topic in portion Amplitude & Frequency Modulation of Avionics
Answer» Correct answer is (b) Error information The explanation is: DISTORTION occurs when the modulating signal amplitude is greater than the amplitude of the carrier, CAUSING incorrect information to be TRANSMITTED. In amplitude modulation, it is PARTICULARLY important that the peak value of the modulating signal be less than the peak value of the carrier.

56.	What happens when the amplitude of the modulating signal is greater than the amplitude of the carrier?(a) Decay(b) Distortion(c) Amplification(d) AttenuationThis question was addressed to me by my school teacher while I was bunking the class.I would like to ask this question from Amplitude Modulation and Modulation Index in division Amplitude & Frequency Modulation of Avionics
Answer» Correct OPTION is (b) Distortion The explanation is: The zero reference line of the modulating signal coincides with the peak value of the unmodulated carrier. Because of this, the RELATIVE amplitudes of the carrier and modulating signal are important. When the AMPLITUDE of the modulating signal is GREATER than the amplitude of the carrier, distortion will OCCUR.

57.	What is the reference line for the modulating signal?(a) Zero line(b) Carrier peak line(c) Modulated peak line(d) Un-modulated peak lineThe question was asked in an online quiz.This intriguing question comes from Amplitude Modulation and Modulation Index topic in chapter Amplitude & Frequency Modulation of Avionics
Answer» Correct choice is (b) CARRIER peak line Easiest explanation: The modulating signal uses the peak value of the carrier rather than ZERO as its reference point. The envelope VARIES above and below the peak carrier amplitude. The zero reference line of the modulating signal COINCIDES with the peak value of the unmodulated carrier.

58.	What is the line connecting the positive and negative peaks of the carrier waveform called?(a) Peak line(b) Maximum amplitude ceiling(c) Modulation index(d) EnvelopeThe question was asked by my school teacher while I was bunking the class.This interesting question is from Amplitude Modulation and Modulation Index in portion Amplitude & Frequency Modulation of Avionics
Answer» Right CHOICE is (d) ENVELOPE Easiest EXPLANATION: An imaginary LINE CONNECTING the positive peaks and negative peaks of the carrier waveform gives the exact shape of the modulating information signal. This line is known as the envelope.

59.	In Amplitude Modulation, the instantaneous values of the carrier amplitude changes in accordance with the amplitude and frequency variations of the modulating signal.(a) True(b) FalseThis question was addressed to me in final exam.Origin of the question is Amplitude Modulation and Modulation Index topic in section Amplitude & Frequency Modulation of Avionics
Answer» Correct answer is (a) True To EXPLAIN I would say: In Amplitude MODULATION, the amplitude of the CARRIER sine wave is varied by the value of the information signal. The instantaneous value of the carrier amplitude changes in accordance with the amplitude and FREQUENCY variations of the modulating signal. The carrier frequency remains constant during the modulation PROCESS, But its amplitude varies in accordance with the modulating signal.