183. High intermediate frequency in a superhet receiver
A. improves selectivity
B. increases tracking problems
C. reduces adjacent channel rejection
D. none of the above
184. The difference between phase and frequency modulation
A. lies in the different difinition of the modulation index
B. is too great to make the two systems compatible
C. is purely theoretical because they are the same in practice
D. lies in the poorer radio response of phase modulation index
185. In a low level amplitude modulation system, the amplifier following the modulated stage must be
A. a class-C amplifier
B. a linear device
C. a non-linear device
D. a harmonic device
186. One can provide two or more voice circuits on the same carrier by using
A.DSB-SC
B. SSB with pilot carrier
C. ISB systems
D. SSB-BC system
187. 100 percent modulation is produced in AM when carrier
A. amplitude equal signal amplitude
B. amplitude exceeds signal amplitude
C. frequency equals signal frequency
D. frequency exceeds signal frequency
188. Modulation is the process of
A. reducing distortion in RF amplifiers
B. generating constant-frequency radio waves
C. improving thermal stability of a transistor
D. combining audio and radio frequency waves at the transmitting end of a communication system
189. In RF amplifiers neutralisation is used to
A. improve selectivity
B. stop oscillations
C. increase bandwith
D. all of the above
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