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ECE Objective Questions { Radar Engineering and Satellite Communication }

85. With reference to the integration time required by the radar to resolve two doppler shifts repa rated by (Afd)
A. the integration time is independent of (8fd),
B.the integration time is directly proportional to (Afd)
C. the integration time is inversely proportional to (Afd)
D. the integration time is proportional to square root of (Afd)

86. The doppler shift produced by a radar operating at 1 GHz from a target, moving with a velocity that has a radial component only the radar axis of 100 m/s, would be
A. 667 Hz
B. 667 IcHz
C. 6.67 kHz
D. 333.3 Hz

87. When the target is moving away from the CW doppler radar, the received frequency
A. is higher than the transmitted frequency
B. is lower than the transmitted frequency
C. has a lot of harmonic content
D. none of these

88. A ship sailing at a radial speed of 10 m/s towards on HF radar operating at 3 MHz would produce a doppler shift of
A. 0.1 Hz
B. I Hz
C. 0.2 Hz
D. 2 kHz

89. The beam width of a radar antenna is 0.1 radian in the azimuth direction and 0.05 radian in the elevation direction. The number of beam positions needed to fill the complete sphere would be
A. 4000 it
B. 100 it
C. 300 TE
D. 800 TC

90. With reference to tracking radars, the problems of pulse to pulse variations in echo amplitudes
A. is given by occurs in monopulse tracking technique
B.is overcome in simultaneous lobing technique
C. is overcome in lobe switching technique
D. is overcome in conical scan technique

91. One of the following is an HF radar system
A. Moving Target Indicator (Mu)
B. Pulse doppler radar
C. FM-CW radar
D. Over-the-horizon radar

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