1
GATE ECE 1991
Fill in the Blanks
+2
-0
Two resistors $$\,{R_1}$$ and $$\,{R_2}$$ (in ohms) at temperatures $${T_1}{}^ \circ K$$ and $${T_2}{}^ \circ K$$ respectively, are connected in series. Their equivalent noise temperature is.
2
GATE ECE 1989
+2
-0.6
Zero mean Gaussian noise of variance N is applied to a half wave rectifier. The mean squared value of the rectifier output will be:
A
Zero
B
N/2
C
$$N/\sqrt 2$$
D
N
3
GATE ECE 1989
MCQ (More than One Correct Answer)
+2
-0.6
A part of a communication system consists of an amplifier of effective noise temperature, $$Te = \,\,21\,\,{}^ \circ K\,$$, and a gain of 13 dB, followed by a cable with a loss of 3 dB. Assuming the ambient temperature to be $$300{}^ \circ \,K$$, we have for this part of the communication system,
A
effective noise temperature $$= 30{}^ \circ \,K$$
B
effective noise temperature $$= 36{}^ \circ \,K$$
C
noise figure = 0.49 dB
D
noise figure = 1.61 dB
4
GATE ECE 1987
+2
-0.6
White Gaussian noise is passed through a linear narrow band filter. The probability density function of the envelope of the noise at the filter output is:
A
Uniform
B
Poisson
C
Gaussian
D
Rayleigh
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