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ECE Objective Questions { Digital Communication System }



106. In a fiber optic communication link, the source to fiber coupling efficiency is dependent on
A. model dispersion
B. numerical operature
C. v-number
D. core radius

107. The type of sourcemodulation required for digital communication using a fiber optic link set up is
A. frequency modulation
B. amplitude modulation
C. intensity modulation
D. phasemodulation

108. For a one kilometer length of step index multimode fiber with n1 = 1.5 and A = 0.01, assuming that the information carrying capacity is limited just by the intermodal dispersion, the minimum inter-pulse separation for the transmitted bit stream would be
A. 20 ns
B. 50 ns
C. 100 ns
D. none of these

109. In a grated index fiber, as radial distance (r) is varied from fiber axis to the core cladding interface, the numerical aperture
A. increases
B. decreases
C. remains unaffected
D. none of these

110. If (L) is the length of the fiber, then for length of fibers, the pulse spreading per km is directly proportional to
A. L
B. L2
C.L4
D. none of these

111. If (L) is the length of the fiber, then for longfiber lengths, pulse spreading per km is directly proportonal to
A. L
B. J-
C.01,2
D.1//17,

112. A given fiber has core refractive index of 1.5 and a core cladding index difference factor (A) of 0.01125. The numerical aperature is
A.2.25
B.0.5
C. 0.225 (d) 0.252
D.

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