1. Correct statement/s about Duplex communication system is/are-
A. Two way transmission of signal is not possible B. It is also called as broadcasting
C. Its example is Telephone D. All of the above
2. Frequency range of ultra high frequency (UHF) is-
A. 3 to 30 MHz B. 30 TO 300 MHz C. 300 MHz to 3 GHz D. 3 to 30 GHz
3. The noise originates from sun and outer space is called-
A. Man made noise B. Extra terrestrial noise
C. Atmospheric Noise D. Burst Noise
4. -------is a type of analog pulse modulation.
A. PAM B. PPM C. PCM D. Both A and B
5. In AM, Information DO NOT contains in........
A. Carrier B. Lower Side band C. Upper Sideband D. Both B and C
6. The % power saving in SSB signal if AM wave is modulated to a depth of 100% and 50% is—
A. 56.89, 66.99 B. 83.33, 94.44 C. 88.88, 99.99 D. 100, 50
7. Power requirement in ascending order-
A. SSB-DSBFC-DSBSC-VSB B. DSBFC-DSBSC-SSB-VSB
C. SSB-VSB-DSBSC-DSBFC D. VSB-SSB-DSBSC-DSBFC
8. Over modulation in AM occurs when..........
A. m>1 B. m<1 C. m=1 D. Independent on 'm'
9. In FM, modulation index is a ratio of--------
A. Max. frequency deviation to modulating frequency
B. Modulating frequency to Max. frequency deviation
C. modulating frequency to carrier frequency
D. Max. frequency deviation to Carrier amplitude
10. Noise immunity in descending order.......
A. AM-FM-PM B. AM-PM-FM C. PM-AM-FM D. FM-PM-AM
11. Following statement is NOT TRUE for low level modulation,
A. Generation of AM takes place at low power level.
B. Class C amplifier is used for signal amplification.
C. Class A, B or AB amplifier is used for signal transmission.
D. Both A and C
12. Following statement is TRUE in low level modulation,
A. Generation of AM takes place at High power level.
B. Class C amplifier is used for signal amplification.
C. Class A, B or AB amplifier is used for signal transmission.
D. Both A and B
13. Following are the requirement of High level modulator-
A. Tuned circuit B. Current pulse generator C. Both A and B D. None of these
14. Following are the problems associated with TRF receiver-
A. Instability B. Variation in bandwidth over the tuning range
C. Insufficient selectivity at high frequencies D. All of the above
15. In reactance modulator, transistor or FET is operated as variable reactance (Inductive or capacitive)-
A. TRUE B. FALSE
16. RF amplifier is used to-
A. Improve signal to Noise ratio B. Match receiver input impedance to antenna impedance
C. Both A and B D. None of these
17. Amplitude limiting is provided in-
A. Balanced slope detector B. Phase discriminator C. Ratio detector D. None of these
18. Following circuit is used to generate sum and difference frequency components-
A. Mixer B. IF amplifier C. LC Filter D. Limiter
19. FM Detector……….
A. Convert frequency to amplitude B. Do not respond to amplitude changes
C. Both A and B D. None of these
20. Amplitude limiting is not provided in balance slope detector.
A. TRUE B. FALSE
21. Square law detector and envelop detector are the types of-
A. AM Detector B. FM Detector C. PM Detector D. None of these
22. For delayed ACG----
A. Cost is high B. Used in high quality receiver
C. Both A and B are correct D. Both A and B are wrong
23. The maximum frequency that is returned back to earth by the atmospheric layer when the wave is incident normal to it, called as -
A. Critical frequency B. Cut off frequency C. Maximum usable frequency D. None of these
24. Variation or fluctuation in the signal strength at the receiver is called as-
A. Fading B. Hand off C. Hopping D. None of these
25. Duct propagation is observed at-
A. Low frequencies B. Very high microwave frequencies
C. Audio frequency D. Medium wave frequency
26. Sky wave propagation exist in the range-
A. 30 KHz- 3 MHz B. 3 MHz- 30 MHz C. 30 MHz- 3 GHz D. Above 3 GHz
27. Distance of troposphere from earth surface approximately is-
A. 5 KM B. 10 KM C. 15 KM D. 20 KM
28. By which phenomenon does the energy transmission take place between the walls of the tube in waveguides?
A. Reflection B. Refraction C. Dispersion D. Absorption
29. For a matched line, the input impedance will be equal to
A) Load impedance B) Characteristic impedance C) Output impedance D) Zero
30. When VSWR is equal to zero, this means
A. that no power is applied B. that the load is purely resistive
C. that the load is a pure reactance D. that the load is opened
31. ______ is the ratio of reflected voltage to the forward travelling voltage.
A. SWR B. VSWR C. Reflection coefficient D. ISWR
32. Transmission line must be matched to the load to ______.
A. transfer maximum voltage to the load B. transfer maximum power to the load
C. reduce the load current D. transfer maximum current to the load
33. The energy that neither radiated into space nor completely transmitted.
A. Reflected waves B. Captured waves C. Incident waves D. Standing waves
34. The standing wave ratio is equal to _______ if the load is properly matched with the transmission line.
A. Infinity B. 0 C. -1 D. 1
35. Antenna is-
A. Input transducer B. Output transducer C. Both A and B D. None of these
36. In antenna, power losses takes place due to-
A. Corona effect B. Eddy current losses C. Both A and B D. None of these
37. Advantages of folded dipole antenna-
A. High input resistance B. High bandwidth C. Impedance matching D. All of these
38. Factors considered for selections of feed point is-
A. Antenna impedance B. Feedpoint impedance C. Both A and B D. None of these
39. Following antenna is used in direction finding-
A. Loop antenna B. Microstrip antenna C. Ferrite rod antenna D. Yagi Uda antenna
40. Following antenna is used in mobile device-
A. Yagi Uda B. Horn antenna C. Microstrip patch antenna D. Dish antenna
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