Numerical - Depth of Modulation/ Modulation Index

Calculate the depth of modulation when a transmitter radiates a signal of 9.8KW after modulation and 8KW without modulation of the signal.

a.) 80%
b.) 67%
c.) 50%
d.) 100%

Correct Answer: 67%

Explanation:

P_total = 9.8KW

P_c = 8KW

Power of the signal (P_total) transmitted by a transmitter after modulation is given by

P_total = P_c (1+ m²/2)

Where P_c is the power of carrier i.e., without modulation

M is the modulation index

Therefore,
9.8= 8(1+ m²/2)
9.8/8=1+ m²/2
m=0.67 = 67%