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Electronics and Communication Engineering - Exam Questions Papers

Exercise : Exam Questions Papers - Exam Paper 11
16.
The Boolean expression B⊕E is a simplified version of expression ABE + BCDE+ BC D E + A B D E + B C D E + A B D E then which of the following choice is correct?
  1. don't care conditions doesn't exist
  2. don't care conditions exist
  3. d( 16, 18, 20, 23, 27, 29) is the set of don't care conditions
  4. d( 16, 20, 22, 27, 29) is the set of don't care conditions
1 only
2 and 3 only
2 and 4 only
data insufficient
Answer: Option
Explanation:

Reduced form of the given expression is B ⊕ E:

A BE + BCDE + B C D E + A B D E + B C D E + A B D E

Now we draw a K-map for 5 variables :

Since we can realize B ⊕ E i.e. BE + B E as shown above, the K-map drawn should have don't care conditions that will be taken into consideration and will be grouped; along with l's.

∴ We have don't care conditions with a set d( 16, 20, 22, 27, 29).

17.
A white noise X(t) with two-sided power spectral density 1 x 10-10 W/Hz is input to a filter whose magnitude squared response is shown below.

The power of the output process Y(t) is given by
5 x 10-7W
1 x 10-6W
2 x 10-6W
5 x 10-6W
Answer: Option
Explanation:

Since bandwidth is 10 kHz, thus output power is 10 x 10-11 x 10 x 103 = 1 x l0-6 W.

18.
A short vertical grounded antenna is required to radiate at 1 MHz. The effective height of the antenna is 302 m. The calculated value of radiation resistance is
1.58 Ω
158 Ω
15.8 Ω
none
Answer: Option
Explanation:

Rr = 80p2.

19.
The following circuit diagram resembles :
logic 0
logic 1
f(A, B, C) = Σm(0, 1, 4, 6, 7)
none
Answer: Option
Explanation:

20.
Consider an angle modulated signal
x(t) = 6cos[2p x 106t + 2sin(8000pt) + 4cos(8000pt)] V
The average power of x(t) is
10W
18W
20W
28W
Answer: Option
Explanation:

.

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