IndiaBIX

Electronics and Communication Engineering - Communication Systems

Exercise : Communication Systems - Section 1
36.
It is desired that transmission line and load should match for a range of frequencies. The best method is
to use a balun
to use a single stub of adjustable position
to use a double stub
to use a broad band amplifier
Answer: Option
Explanation:

When matching over a range of frequencies is desired, double stub is necessary.

37.
Which of the following has the highest input impedance?
CE
CB
CC
Push pull
Answer: Option
Explanation:

CC connection has very high input impedance and low output impedance.

38.
In a fascimile reproduction time to scan one line is 2 ms. If it has 4% blanking, the visible trace time is
1.92 ms
2.08 ms
50 ms
0.08 ms
Answer: Option
Explanation:

(2 ms) (1 - 0.04) = 1.92 ms.

39.
Consider the following statements
  1. The amplitude of an FM wave is constant
  2. FM is more immune to noise than AM
  3. FM broadcasts operate in upper VHF and UHF frequency ranges
  4. FM transmitting and receiving equipments are simpler as compared to AM transmitting and receiving equipments
Which of the above are correct?
1, 2, 3, 4
1, 2, 3
2, 3, 4
1, 3, 4
Answer: Option
Explanation:

FM equipments are complex as compared to AM equipments.

40.
Signal to noise ratio of microphone is defined as the ratio of output when the sound pressure is __________ to the output in the absence of any sound signal.
0.5 Pa
0.2 Pa
0.1 Pa
0.01 Pa
Answer: Option
Explanation:

0.1 Pa (= 0.5 x 10-4 W/m2) is taken as standard sound pressure for defining S/N ratio of microphones.

Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers