Sinusoids, Noise, & Their Spectrum
by Mike Martin

Consider a sum of three sinusoids and another term that represents noise (actually random numbers drawn from a restricted interval):

f (t) = A1 sin(ω1 2π n / N ) + A2 sin(ω2 2π n / N ) + A3 sin(ω3 2π n / N ) + A4 V

The user inputs values for the parameters A1, A2, A3, A4, ω1, ω2, ω3, and N. Note that N is the number of sample points of the sinusoidal signal. Also the noise (or random variable) is drawn from uniform distribution within the interval [-1/2, 1/2]; the variable V represents this noise. It may be of interest to examine the spectrum of the sinusoidal signal when there is no noise -- set A4 = 0. The first graph is that of the signal and the second graph is that of the Fouler spectrum.

Enter in the values of the parameters, then press the "Visualize" button.

A1 =

ω1 =

A2 =

ω2 =

A3 =

ω3 =

A4 =

N =