| 1. | Am amplitude modulated double sideband suppressed carrier signal is given by [1+am Cos 2 fat] Cos 2 fmtcos2 fct, where f c is the frequency of the carrier signal. The modulating signals is ? | |
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Am Cos 2 fat
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Am Cos 2 fatcos2 fm t
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[1+Am cos2 fat] cos2 fm t
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1+Am Cos 2 fat
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Report Question| 2. | A modulating Voltage e m = 25sin (3.14x103) & carrier voltage e c = 5 sin(628x103t). What will the upper & lower sideband frequency ? | |
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USB=10.0515KHz LSB = 10.0485 KHz
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USB= 10.24 KHz LSB = 10.3 KHz
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USB= 10.30 KHz LSB = 10.20 KHz
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USB = 10.3515 KHz LSB = 10.2485 KHz
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| 3. | If transmitted power = Pt, modulation index = m1 carrier power = Pc, then total transmitted power in a conventional A.M. system, is given as ? | |
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Pt= 2Pc (1+m2/2)
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Pt= Pc (1+m2/2)
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Pt= 0.5Pc (1+m2/2)
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Pt= 0.3Pc (1+2/2)
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| 4. | An AM radio station operating at 530KHz is permitted to broadcast audio frequencies up to 5KHz, the upper and lower side frequencies are ? | |
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f USB = 535KHz, f LSB = 525KHz
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f USB = 525KHz, f LSB = 535KHz
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f USB = 535KHz, f LSB = 535KHz
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f USB = 525KHz, f LSB = 525KHz
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| 5. | When the modulating frequency is doubled the modulation index is halved, and the modulating voltage remains constant. The modulation system is: 1 Amplitude 2 Phase Modulation 3 Frequency Modulation ? | |
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Any of I, II or III
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Only II
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Only III
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Only I
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| 6. | Noise has the greatest effect in a communication system when if interferes with the signal______ ? | |
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In the transducer
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In the transmitter
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In the receiver
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In the channel
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| 7. | In case of channel length modulation ? | |
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Output current increases with output voltage
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Output current decreases with output voltage
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Output current increases with input voltage
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Output current decreases with input voltage
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| 8. | In FM signal with a modulation index mF is passed through a frequency Tripler. The wave in the output of the Tripler. The wave in the output of the Tripler will have a modulation index of ? | |
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Mf
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Mf/3
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Mf/9
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3mf
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| 9. | Which one of the following statements is NOT true ? | |
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A frequency modulated signal is produced when a modulating signal m (t) is integrated and applied to a phase modulator
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For a sinus dally modulated FM carrier, it is possible that for particular values of the modulation index ?, all the power in the carrier
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When carrier to noise ratio is high, an increase in the transmission bandwidth decreases the figure of merit of an FM system
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A phase modulated signal is produced when a modulating signal m(t) is differentiated and applied to a frequency modulator
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| 10. | A FM transmitter has a maximum deviation of 12 KHz and a maximum modulating frequency of 12 KHz. The bandwidth by Carson’s rule is KHz is ? | |
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24
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36.8
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48
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37.8
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