Amplitude Modulated Signal 

Visualize an amplitude modulated signal, based on a pair of independent fractional Brownian motion processes.

In[1]:=

X a = RandomFunction[FractionalBrownianMotionProcess[.3], {1, 5000, 1}][ "PathStates"];

In[2]:=

X b = RandomFunction[FractionalBrownianMotionProcess[.8], {1, 5000, 1}][ "PathStates"];

In[3]:=

X ListLinePlot[Table[a[[ t]] Cos[3 t] + b[[t]] Sin[3 t], {t, 1, 5000}], ColorFunction -> "Rainbow", ImageSize -> 200]

Out[3]=