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Electronics and Communication Engineering - Exam Questions Papers

Exercise : Exam Questions Papers - Exam Paper 2
36.
An 8 level encoding scheme is used in a PCM system of 10 kHz channel BW. The channel capacity is
80 kbps
60 kbps
30 kbps
18 kbps
Answer: Option
Explanation:

C = 2B log2 M;

M = 8 = 23, log2 M = 3 bits

= 2 x 10 x 103 x 3 = 60 kbps.

37.
For the power amplifier circuit shown below, the maximum power dissipated by both output transistor is
9.66 W
30.11 W
31.66 W
33.66 W
Answer: Option
Explanation:

The maximum power dissipated by both output transistor is maximum

38.
For static electric and magnetic fields in an homogenous source-free medium, which of the following represents the correct form of Maxwell's equations?
Δ.E = 0
Δ x B = 0
Δ.E = 0
Δ.B = 0
Δ x E = 0
Δ x B = 0
Δ x E = 0
Δ.B = 0
Answer: Option
Explanation:

Curl of electric field is zero. Divergence of magnetic field is zero.

39.
A periodic rectangular signal, x(t) has the waveform shown in the given figure. Frequency of the fifth harmonic of its spectrum is __________
200 Hz
250 Hz
400 Hz
1250 Hz
Answer: Option
Explanation:

The periodic time = 4 ms = 4 x 10-3 s

∴ The fundamental frequency

∴ Frequency of the 5th harmonic

= 250 x 5 = 1250 Hz.

40.
An antisymmetric filter having odd number of coefficient may have a performance as
low pass
high pass
band pass
all pass
Answer: Option
Explanation:

Consider an anti-symmetric filter response with order 5.

h(n) = [h(2), h(1), h(0), - h(1), - h(2)]

We know, H(0) = addition of all component values.

Hence H(0) = h(0)

Similarly H(p) = addition of all component values with alternate negative sign.

= h(2) - h(1) + h(0) + h(1) - h(2) = h(0)

Hence we get all pass filter.

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