Electronics and Communication Engineering - Communication Systems

36.

Assertion (A): In standing wave pattern, the nodes and anti nodes are separated by half wave-length

Reason (R): When line is terminated in resistance RL, the standing wave ratio is SWR = Z0/RL or RL/Z0

Both A and R are correct and R is correct explanation of A
Both A and R are correct but R is not correct explanation of A
A is correct but R is wrong
A is wrong but R is correct
Answer: Option
Explanation:

.


37.
An amplifier has an input resistance of 10 kΩ and the noise voltage is 10 μV. If two such resistances of 10 kΩ each are connected in series at the input, the total noise voltage is about
20 μV
5μV
14.14 μV
10 μV
Answer: Option
Explanation:

Noise voltage = 10 = 14.14 μV.


38.
A 400 W carrier is modulated to a depth of 75 percent. The total power in modulated wave will be
38.5 W
400 W
512.5 W
615.5 W
Answer: Option
Explanation:

Pc = 400 W, m = 0.75


39.
In a colour TV receiver the bandwidth of RF amplifier is
exactly equal to channel width
a little less than channel width
a little more than channel width
either (a) or (b)
Answer: Option
Explanation:

It is kept a little more than channel width so that reception is not restricted.


40.
An FM signal with a deviation is passes through the mixer, and has its frequency reduced five fold. The deviation in the output of the mixer is
Δ
Δ/5
indeterminant
Answer: Option
Explanation:

Δf (frequency deviation) is independent of fm , Δf depends only upon amplitude of message signal.

Δf = kf.Am .