7.5 Discrete Fourier Decomposition - By Hand
5 pts
You now sample the same $f(t)$ at 4-Hz (i.e., $\Delta t = 0.25$), starting with $f_1 = 0$ at $t_1 = 0$, and getting four discrete points $(t_j, f_j)$ over one period $\rightarrow$
a) Write out the values $(t_j, f_j)$ of these four points. What's $N$ and $2N$?
b) Use the four points in (a) to calculate (by-hand) the DFT for $f(t)$:
i. Calculate all the Fourier coefficients $A_k$ and $B_k$, for $0 \le k \le N$,
ii. Substitute the values of the coefficients into the discrete Fourier Series representation of the earthquake function $f(t) = B_0 + \sum(... etc. ...)$ and express in a simplified form.