IndiaBIX

Electronics and Communication Engineering - Communication Systems

Exercise : Communication Systems - Section 4
21.
Some advantages of optical fibre cables are
  1. small diameter
  2. Immunity to cross talk and EM interference
  3. Laser and LED modulation methods lend themselves ideally to digital operation
Which of the above are correct?
1 only
1 and 2
1, 2, 3
2, 3
Answer: Option
Explanation:

Fibre optic cables have all these advantages.

22.
The contrast control in colour TV receiver is done by
chroma amplifier
SAW filter
video detector
luminance amplifier
Answer: Option
Explanation:

Luminance amplifier changes the luminance levels and provides contrast control.

23.
The requirements of carrier frequency are
precise frequency value
low frequency drift
both (a) and (b)
neither (a) nor (b)
Answer: Option
Explanation:

Both should have a precise value and low drift.

24.
If N bits are lumped together to get an N-bit symbol, the possible number of symbols is
2N
2N - 1
2N - 2
2N - 4
Answer: Option
Explanation:

Each bit can have two levels. Hence 2N.

25.
The received signal frequency at any time of a super-heterodyne receiver having IF = 456 kHz is 1 MHz. The corresponding image signal is
within the medium band
outside the medium band
depend upon modulation index
depends on Modulating frequency
Answer: Option
Explanation:

Image signal frequency = Received signal frequency - 2 x Intermediate frequency.

= 1 MHz - 2 x 456kHz

1 MHz - 912 kHz 88 kHz

which lies in medium bond.

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