11) Light travels along the optical fibers by which mechanism ?
a) Refraction
b) Reflection
c) Scattering
d) Total internal reflection
12) Quadrature multiplexing is
(a) the same as FDM
(b)the same as TDM
(c) a combination of FDM and TDM
(d)quite different from FDM and TDM
13) Which ionosphere layer is responsible for return of a radiation at frequency 30 MHz ?
a) D
b) E
c) F
d) All of above
14) Tropospheric scatter communication is used for which frequency band ?
a) HF
b) VHF
c) UHF
d) VLF
15) What was the first commercial geostationary communication satellite ?
a) INTELSAT 1
b) ECHO
c) INSAT-1A
d) SPUTNIK
16) Which one of the following photo-detector does not provide gain ?
a) Photo-transistor
b) Photo conductor
c) Avalanche photodiode
d) p-i-n photodiode
17) A balanced modulation, is used in the generation of which of the following ?
a) DSB-SC signal
b) FM signal
c) PM signal
d) PAM signal
18) Which one of the following is correct ? in a TDM system each signal is alloted in a frame a unique and fixed
a) frequency slot
b) time slot
c) amplitude slot
d) phase slot
19) During power measurement the out power measured was -90 dBm. What is the measured power in W ?
a) 1 mW
b) 1 pW
c) 10 W
d) 1 W
20) In order to permit the selection of 1 out of 16 equiprobable events, what is the number of bits required ?
a) 8
b) 4
c) log 10 16
d) 2