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1) What is the maximum transmission efficiency of an AM signal? a. 64.44% b. 33.33% c. 56.66% d. 75.55%
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2) In synchronous detection of AM signal a. Carrier is locally generated b. Passed through a low pass filter c. The original signal is recovered d. All of the above
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3) Requirements of synchronous detection of AM signal are: a. Local generation of carrier b. The frequency of the locally generated carrier must be identical to that of transmitted carrier c. The phase of the locally generated carrier must be synchronized to that of transmitted carrier d. All of the above
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4) Disadvantages of using synchronous detection of AM signal are: a. Needs additional system for generation of carrier b. Needs additional system for synchronization of carrier c. Receiver is complex and costly d. All of the above
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5) Quadrature Amplitude Modulation (QAM) is a. Have same bandwidth used for two DSB-SC signals b. Is also known as Bandwidth Conservation scheme c. Is used in color television d. All of the above
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6) Pilot carrier is a. Used with DSB-SC signal b. A small carrier transmitted with modulated signal c. Used for synchronization with local carrier at the receiver d. All of the above
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7) Generation of SSB SC signal is done by a. Phase discrimination method b. Frequency discrimination method c. Product modulator d. Both a and b
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8) Limitations of Frequency discrimination method are: a. Cannot be used for video signals b. Designing of band pass filter is difficult c. Both a and b d. None of the above
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9) Phase shift method is a. Includes two balanced modulators b. Two phase shifting networks c. Avoids the use of filters d. All of the above
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10) Vestigial side band signals are detected by a. Filters b. Synchronous detection c. Balanced modulator d. None of the above
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11) Automatic gain control is a. Provides controlled signal amplitude at the output b. Adjusts the input to output gain to a suitable value c. Is used in AM radio receiver d. All of the above
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12) In an Amplitude Modulation a. Amplitude of the carrier varies b. Frequency of the carrier remains constant c. Phase of the carrier remains constant d. All of the above
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13) If modulation index is greater than 1 a. The baseband signal is not preserved in the envelope of the AM signal b. The recovered signal is distorted c. It is called over modulation d. All of the above
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14) Examples of low level modulation are a. Square law diode modulation b. Switching modulation c. Frequency discrimination method d. Both a and b
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15) Squelch circuit is a. Suppresses output audio b. Works when there is insufficient desired input signal c. Is used to suppress the unwanted channel noise when there is no reception by the receiver d. All of the above
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16) In Automatic gain control of the AM receiver a. Gain of the receiver is adjusted b. The gain adjustment depends upon the strength of the received signal c. The output provided is a DC voltage d. All of the above
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17) The factors that determine the sensitivity of super heterodyne receiver are a. Gain of the IF amplifier b. Noise figure of the receiver c. Gain of RF amplifier d. All of the above
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18) Selectivity of a receiver: a. Changes with incoming signal frequency b. Is poorer at high frequencies c. Is the rejection of the adjacent channel at the receiver d. All of the above
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19) Advantages of using an RF amplifier are: a. Better selectivity b. Better sensitivity c. Improved signal to noise ratio d. All of the above
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20) Intermediate frequency (IF) should be carefully chosen as a. High IF results in poor selectivity b. High IF results in problems in tracking of signals c. Image frequency rejection becomes poor at low IF d. All of the above
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