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ECE Objective Questions { Television Engineering }

78. Indicate which of the following frequencies cannot ordinarily by used for beyond-the-horizon terrestrial communication :
A. 600 kHz
B. 15 MHz
C. 12 GHz
D.both A and C

79. In the visible spectrum of electromagnetic waves, the following has longest wavelength
A. green
B. red
C. blue
D. white

80. A super-heterodyne receiver with an IF of 450 kHz is tuned to a signal of 1200 kHz, the image frequency is ____ kHz.

81. D-layer in the ionosphere is largely present
A. all the 24 hours
B. during night only
C. during day only
D. during cloudy only

82. The modulator stage in a radio transmitter is normally
A. class-C
B. class-B push-pull
C. class-A
D. class-D

83. If the carrier of a 100% modulated AM wave is suppressed, the percentage saving of power will be

84. Which of the following frequencies will be most suitable for satellite communication?
A. 30 MHz
B. 300 MHz
C. 2500 MHz
D. 3000 MHz

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