176. The mean square volue of the shot noise current
A. varies inversely as average current
B. is independednt of average current
C. varies as 4average current
D. varies directly as average current

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177. Quadrature multiplexing is
A. same as FEM
B. same as TDM
C. a combination of FDM and TDM
D. the scheme where same carrier frequency is used for two different signals

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178. For a given data rate, the bandwidth required with m-ary transmission is smaller than that for binary transmission by
A. log2m
B.2log2 m
C. log2m
D.2

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179. Four voice signals, each limited to 4 kHz and sampled at Nyquist rate, are converted into binary PCM signal using 256 quantisation levels. The bit transmission rate for the time-division multiplexed signal will be
A. 8 kbps
B. 64 kbps
C. 256 kbps
D. 512 kbps

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180. In ionosphere, the incidence angle is 60. The maximum unstable frequency will be
A. 2fc
B. fc2
C.f
D. /3f

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181. In a PCM, the amplitude levels are
A. 5 lcHz
B. 35 kHz
C. 70 lcHz
D. 5 MHz

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182. In a DM (delta modulation) system, the granular (idling) noise occurs when the
A. modulation signal increases rapidly
B. pulse rate decreases
C. modulating signal remains constant
D. pulse amplitude decreases

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