211. In TV the line blanking period is
A. slightly less than the horizontal retrace
B. slightly ore than the horizontal retrace
C. exactly equal to the horizontal retrace
D. none of the above
212. Operator (y) in a image orthicon tube is
A. unity
B. zero
C. varies between unity and zero
D. none of the above
213. The demodulation of the sound signals in a TV receiver is accomplished by
A. Linear detector
B. product dector
C. discriminator
D. envelop dector
214. The service range of TV transmitter is determined by
A. the height of the transmitting aerial
B. the height of the transmitting and that of the receiving antenna
C. the height of the transmitting and that of the receiving antenna and power of the transmitter
D. the height and gain of the transmitting and receiving antenna and power of the transmitter
215. Another name for the horizontal retrace in a TV receiver is the
A. flyback
B. brust
C. damper
D. ringing
216. As the TV picture tube size increase
A. voltage required for picture tube anode ncreases
B. voltage required for picture tube anode decreases
C. voltage required for picture tube anodes does not change
D. none of the above
217. In a TV receiver the contrast is controlled by
A. ac voltage in video signal
B. dc voltage in video signal
C. both ac and dc voltage
D. none of the above
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