Question

The carrier wave is given by C(t) = 2sin(8πt) volt. The modulating signal is a square wave as shown. Find modulation index.

Answer 1

Modulation index (μ) is the ratio of the amplitude of the modulating signal to the amplitude of the carrier wave. The generalised equation of a carrier wave is given below: c(t) =Acsinωct The generalised equation of a modulating wave is given below: cm(t)=Acsinωct+μAcsinωmtsinωct Here, μ is defined as AmAc. On comparing this with the equations of carrier wave and modulating wave, we get: Amplitude of modulating signal, Am=1 V Amplitude of carrier wave, Ac=2 V ∴ μ=AmAc=12=0.5