An amplitude-modulated amplifier has a radio frequency output of
| An amplitude-modulated amplifier has a radio frequency output of 50 W at 100% modulation. The internal loss in the modulator is 10 W. The unmodulated carrier power is
A. 40 W
B. 50 W
C. 60 W
D. 80 W
Please scroll down to see the correct answer and solution guide.
Right Answer is: A
SOLUTION
Concept:
The total transmitted power for an AM system is given by:
\({P_t} = {P_c}\left( {1 + \frac{{{μ^2}}}{2}} \right)\)
Pc = Unmodulated carrier Power
μ = Modulation Index
Note: This total power includes the loss power as well.
Calculation:
Given μ = 1 and internal loss = 10 W
∴ The total power transmitted will be:
Pt = 50 + 10 = 60 W
We can now write
\(60= {P_c}\left( {1 + \frac{{{1^2}}}{2}} \right)\)
\(60= {P_c}\left( {1 + \frac{{{1}}}{2}} \right)\)
\(60= {P_c}~(1.5)\)
\(P_c=\frac{60}{1.5}=40~W\)