Communication Engineering - Online Test
Q1. The impulse response of a system is h(t) = tu(t). For an input u(t − 1), the output is
Answer : Option C
Explaination / Solution:
No Explaination.
Q2. Two 4-array signal constellations are shown. It is given that φ1 and φ2 constitute an orthonormal basis for the two constellation. Assume that the four symbols in both the constellations are equiprobable. Let N0/2 denote the power spectral density of white Gaussian noise.
If these constellations are used for digital communications over an AWGN channel, then which of the following statements is true ?
Answer : Option A
Explaination / Solution:
No Explaination.
Q3. The impulse response of a continuous time system is given by h(t) = δ(t - 1) + δ(t - 3). The value of the step response at t = 2 is
Answer : Option B
Explaination / Solution:
No Explaination.
Q4. For a Hertz dipole antenna, the half power beam width (HPBW) in the E-plane is
Answer : Option C
Explaination / Solution:
The beam-width of Hertizian dipole is 1800 and its half power beam-width is 900
Q5. The state variable formulation of a system is given as 
The response y(t) to the unit step input is
Answer : Option A
Explaination / Solution:
No Explaination.
Q6. Consider the amplitude modulated (AM) signal 
For demodulating the signal using envelope detector, the minimum value of Ac should be
For demodulating the signal using envelope detector, the minimum value of Ac should be
Answer : Option A
Explaination / Solution:
Q7. The state variable formulation of a system is given as
The system is
Answer : Option A
Explaination / Solution:
No Explaination.
Q8. The driving point impedance of the following network is given by
The component values are
Answer : Option D
Explaination / Solution:
Q9. Consider an LTI system with impulse response 
If the output of the system is 
then the input, x(t), is given by
If the output of the system is then the input, x(t), is given by
Answer : Option B
Explaination / Solution:
Q10. The circuit shown in the figure is used to charge the capacitor C alternately
from two current sources as indicated. The switches S1 and S2 are mechanically
coupled and connected as follows:
Assume that the capacitor has zero initial charge. Given that u(t) is a unit step function , the voltage vc(t) across the capacitor is given by
Answer : Option C
Explaination / Solution:
