So this particular example I'm giving you a time domain signal, v of t,

and saying plot the frequency spectrum.

And in this particular case, I'm telling you what the two frequency components are.

And you can actually figure that out from the plot because if I look at this,

I've got a low frequency that repeats at this.

So this is, I can figure out what the time is, 1 over t, call it t sub 1.

That's f1, that's the low frequency.

The high frequency you can get by looking at the shorter

peaks that are much faster.

And 1 over t2, that distance is t2, 1 over t2 is f2.

So from this plot, we can figure out what f1 and f2 are.

Now we want to figure out what the amplitudes are of the f1 and

f2 components.

Well that's a little bit more tricky, but you have to realize that

it's a super position of a low frequency and a high frequency signal.

I can look at this signal and kind of figure out what the low frequency average,

the slower moving average of this, and kind of sketch that in.