An audio signal $$v_m = 20\sin 2\pi \times 1500t$$ amplitude modulates a carrier $$v_c = 80\sin 2\pi \times 100000t$$. The value of percent modulation is ______

We have an audio signal $$v_m = 20\sin 2\pi \times 1500t$$ and a carrier wave $$v_c = 80\sin 2\pi \times 100000t$$.

The amplitude of the modulating signal is $$A_m = 20$$ and the amplitude of the carrier wave is $$A_c = 80$$.

The modulation index is defined as $$\mu = \frac{A_m}{A_c}$$.

Substituting the values, $$\mu = \frac{20}{80} = 0.25$$.

The percent modulation is $$\mu \times 100 = 0.25 \times 100 = 25\%$$.

So, the answer is $$25$$.