155. While discussing sharing of a communication satellite by many geographically dispersed Earth stations, DAMA means
A. demand-assigned multiple access
B. decibel attenuated microwave antenna
C. digital analog master antenna
D. dynamically-assigned multiple access

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156. Radio broadcasting is a familiar example of
A. space multiplexing
B. time multiplexing
C. frequency multiplexing
D. none of the above

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157. A modem is
A. a form of comutator
B. a device for digitizing speech
C. a circuit used for suppressing microwave interference
D. an electronic circuit which carries out modulation and demodulation of a carrier frequency

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158. In the case of a 70-MHz IF carrier for a tansponder bandwidth of 36 MHz, energy must lie between ?MHz.
A. 34 and 106
B. 52 and 88
C. 106 and 142
D. 34 and 142

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159. In synchronous detection of an AM signal
A. carrier is completely suppressed
B. both side bands are suppressed
C. only one side band and part of carrier is suppressed
D. one side band and full carrier is suppressed

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160. In envelope detection of an AM waveform
A. one side band and full-amplitude carrier are needed
B. both side bands and full-amplitude carrier are needed
C. only two side bands are needed
D. upper side band and part of carrier are needed

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161. In satellite communication, frequency ,modulation is used because satellite channel has
A. small bandwidth and negligible noise
B. large bandwidth and severe noise
C. maximum bandwidth and minimum noise
D. high modulation index

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