Communications - Online Test
Q1. A white noise process 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.
Answer : Option C
Explaination / Solution:
No Explaination.
Q2. The signal 
is
is
Answer : Option C
Explaination / Solution:
No Explaination.
Q3. A speed signal, band limited to 4 kHz and peak voltage varying between +5 V and -5 V, is sampled at the Nyquist rate. Each sample is quantized and represented by 8 bits.
If the bits 0 and 1 are transmitted using bipolar pulses, the minimum bandwidth required for distortion free transmission is
Answer : Option B
Explaination / Solution:
Q4. Which of the following statements is true regarding the fundamental mode of the metallic waveguides shown ?
Answer : Option A
Explaination / Solution:
Rectangular and cylindrical waveguide doesnβt support TEM modes and have cut off frequency. Coaxial cable support TEM wave and doesnβt have cut off frequency.
Q5. 
In the following network, the switch is closed at t = 0- and the sampling starts from t = 0. The sampling frequency is 10 Hz.
The samples x(n), n = (0, 1, 2, ...) are given by
Answer : Option B
Explaination / Solution:
No Explaination.
Q6. 
In the following network, the switch is closed at t = 0- and the sampling starts from t = 0. The sampling frequency is 10 Hz.
The expression and the region of convergence of the z -transform of the sampled signal are
Answer : Option C
Explaination / Solution:
Q7. Suppose that the modulating signal is 
and the carrier signal is 
, which one of the following is a conventional AM signal without over-modulation
and the carrier signal is , which one of the following is a conventional AM signal without over-modulation
Answer : Option C
Explaination / Solution:
No Explaination.
Q8. Consider an angle modulated signal 
The average power of x(t) is
The average power of x(t) is
Answer : Option B
Explaination / Solution:
No Explaination.
Q9. If the scattering matrix [S ] of a two port network is 
then the network is
then the network is
Answer : Option C
Explaination / Solution:
Q10. A transmission line has a characteristic impedance of 50 Ξ© and a resistance of 0.1Ξ©/m . If the line is distortion less, the attenuation constant(in Np/m) is
Answer : Option D
Explaination / Solution:
For distortion less transmission line characteristics impedance
