Communication Engineering - Online Test
Q1. Let the Laplace transform of a function F(t) which exists for t > 0 be F1(s) and
the Laplace transform of its delayed version 
be the
complex conjugate of F1(s) with the Laplace variable set as s=σ + jw. If G(s) = 
, then the inverse Laplace transform of G(s) is
be the
complex conjugate of F1(s) with the Laplace variable set as s=σ + jw. If G(s) = , then the inverse Laplace transform of G(s) is
Answer : Option B
Explaination / Solution:
Q2. During transmission over a certain binary communication channel, bit errors occur independently with probability p. The probability of AT MOST one bit in error in a block of n bits is given by
Answer : Option C
Explaination / Solution:
Q3. A zero mean random signal is uniformly distributed between limits –a and +a and its mean square value is equal to its variance. Then the r.m.s value of the signal is
Answer : Option A
Explaination / Solution:
Q4. In a GSM system, 8 channels can co-exist in 200 kHz bandwidth using TDMA.
A GSM based cellular operator is allocated 5 MHz bandwidth. Assuming a
frequency reuse factor of 1/5, i.e. a five-cell repeat pattern, the maximum number
of simultaneous channels that can exist in one cell is
Answer : Option B
Explaination / Solution:
Q5. The response h(t) of a linear time invariant system to an impulse δ(t) , under
initially relaxed condition is 
The response of this system for a
unit step input u(t) is
The response of this system for a
unit step input u(t) is
Answer : Option C
Explaination / Solution:
Q6. In a Direct Sequence CDMA system the chip rate is 1.2288 × 106 chips per
second. If the processing gain is desired to be AT LEAST 100, the data rate
Answer : Option A
Explaination / Solution:
Q7. Given that f(y) = | y | / y, and q is any non-zero real number, the value of | f(q) - f(-q) | is
Answer : Option D
Explaination / Solution:
Q8. An air-filled rectangular waveguide has inner dimensions of 3 cm × 2 cm.
The wave impedance of the TE2 mode of propagation in the waveguide at a
frequency of 30 GHz is (free space impedance η0 = 377Ω)
Answer : Option C
Explaination / Solution:
Q9. 
A periodic voltage waveform observed on an oscilloscope across a load is shown. A permanent magnet moving coil (PMMC) meter connected across the same load reads
Answer : Option A
Explaination / Solution:
Q10. The
field in a rectangular waveguide of inner dimension a × b is given by 
field in a rectangular waveguide of inner dimension a × b is given by Where H0 is a constant, and a and b are the dimensions along the x − axis and
the y − axis respectively. The mode of propagation in the waveguide is
Answer : Option A
Explaination / Solution:
