# Electronics and Communication Engineering - Exam Questions Papers

31.
A delta modulation system is designed to operate at 3 times the Nyquist rate for a signal with a 3 KHz bandwidth. The quantization step size is 250 mv. The maximum amplitude of a 1 KHz input sinusoidal for which the delta modulator does not show slope overload is :
716.2 mV
500 mV
647.87 mV
400 mV
Explanation:

.

32.
Values of iL, , VC and at t = 0 are given by,
4 Amp, - 4 Amp/sec, 12 volts, - 4 volts/s
4 Amp, 4 Amp/sec, -12 volts, - 12 volts/s
6 Amp, - 2 Amp/sec, 0 volts, - 2 volts/sec
6 Amp, 0 Amp/sec, - 2 volts, - 2 volts/sec
Explanation:

For t = 0 +

iL(0-) = = 6 A

VC(0-) = 0 V

For t = 0+

iL(0+) = 6

VC(0+) = 0

Apply KCL at node V

6 - V = (6 + v)2

6 - V = 12 + 2V

- 6 = 3V

V = VL = - 2V

At t = 0+, = -2

iL = 6 Amp

VC = 0 V

.

33.
A continuous time LTI system is described by

Assuming zero initial conditions, the response y(t) of the above system for the input x(t) = e-2t u(t) is given by
(et - e3t) u(t)
(e-t - 3e-3t) u(t)
(e-t + e-3t) u(t)
(et + e3t) u(t)
Explanation:

y(t) = (e-t - e-3t) u(t).

34.
The analog signal given below is sampled by 600 samples per second
m(t) = 2 sin 480pt + 3 sin 720pt
The folding (maximum) frequency is __________ .
600 Hz
120 Hz
300 Hz
360 Hz
Explanation:

Folding frequency (max.).

35.
In the circuit shown, the power supplied by the voltage source
0 W
5 W
10 W
100 W