Question

The modulation index of a single-tone amplitude modulated (AM) signal is increased from 0.20 to 0.25. The corresponding percentage increases in the transmission power efficiency of the AM signal is______%

• A. 54.6

Answer 1

The correct option is A 54.6
$\text{When}\mu =0.20,{\eta }_1=\frac{{\mu }^2}{2+{\mu }^2}=\frac{0.04}{2.04}=0.0196\text{When}\mu =0.25,{\eta }_2=\frac{{\mu }_2}{2+{\mu }^2}=\frac{0.0625}{2.0625}=0.0303\text{\% Increases in the efficiency}=\frac{{\eta }_2-{\eta }_1}{{\eta }_1}\times 100=\frac{0.0303-0.0196}{0.0196}\times 100=54.6$