148. A FM discriminator changes
A. FM signal into FM signal of low frequency
B. FM signal into FM signal of high frequency
C. FM signal into AM signal
D. FM signal into PM signal
149. A frequency multiplier circuit
A. operates class A
B. is tuned to a harmonic of the input signal
C. needs parasitic oscillations
D. is usually pulse modulated
150. Which system is free from noise?
A. FM
B. AM
C.Both FM and AM
D. None of the above
151. The frequency of the stereo sub-carrier signal in FM broadcasting is
A. 19 kHz
B. 38 kHz
C. 50 IcHz
D. 76 kHz
152. One Angstrom of wavelength (I A?) equals
A. 10-8m
B. 10-10m
C. 1(110m
D. 1 tam
153. In amplitude modulation
A. the amplitude of the carrier varies in accordance with the amplitude of the modulating signal
B. the amplitude of the carrier remains constant
C. the amplitude of the carrier varies in accordance with the frequency of the modulating signal
D. modulating frequency lies in the audio range
154. The bandwidth of DSB suppressed carrier modulation system when the modulating frequency varies between 100 Hz and 5 kHz is
A. 10 Hz
B. 10 kHz
C. 5 kHz
D. 4.9 kHz
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