Blame packages/core/src/m/plate_spectrum.m at main - proof-of-concept/plate-dynamics-lab-2

2% PLATE_SPECTRUM One-sided amplitude spectrum of a real, uniformly sampled signal.

4% [f, A] = plate_spectrum(t, x) applies a Hann window and returns the

5% amplitude A at frequencies f [Hz], scaled so that a steady sinusoid of

6% amplitude a shows a peak of height about a. For a decaying signal the

7% peak heights depend on the record length, so compare shapes and

8% frequencies rather than absolute heights.

10x = x(:).';

11N = numel(x);

12dt = t(2) - t(1);

13win = 0.5 * (1 - cos(2 * pi * (0:N - 1) / (N - 1)));

14X = fft(x .* win);

15nh = floor(N / 2) + 1;

16X = X(1:nh);

17A = abs(X) * 2 / sum(win);

18f = (0:nh - 1) / (N * dt);

19end