169. The shape-factor of a filter-response
A. cannot be applied to crystal filters
B. is the same as the peak-to-valley ratio
C. determines the adjacent-channel selectivity of the filter
D. is equal to the 60 dB bandwidth of a mechanical filter

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170. In adiode, shot noise current is proprotional to, where I = D.C. diode current
A. Ip
B. Ip2
C.
D. Ip3r2

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171. With reference to 'Time division complex' which of the following statements is correct?
A. It interleaves pulses belonging to different transmissions
B. It can be usedwith PCM only
C. It stacks several channels in adjecent frequency slots
D. It combines five groups into a single super group

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172. Which one of the following types of noise gains importance at high frequency?
A. Shot noise
B. Random noise
C. Impulse noise
D. Transit?time noise

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173. The 'Wise figure of an amplifier is 3 dB. Its noise temperature will be about
A. 145 K
B. 290 K
C.580K
D. 870 K

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174. Noise voltage varies ma resistor as
A. 4 KTRB
B.41117---FR B
C. 42.;-1/7-313
D.2e11T-3Fit

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175. The rms noise voltage of an amplifier due to aninput resistor is 20 microvolts in a bandwidth of 2 HMz. If the operating bandwidth is doubled, the noise voltage will become (rounded to nearest whole number).
A. 40 microvoltas
B. 35 microvolts
C. 30 microvolts
D. 20 microvolts

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