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Commit 9a4ba594 authored by Stefano Covino's avatar Stefano Covino
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......@@ -82,11 +82,11 @@ md"""
# ╔═╡ 477704cc-f022-4cc5-a4a4-679387b819bd
# ╠═╡ show_logs = false
md"""
cm"""
## A reminder of the CFT
***
- Given a continuous signal g(t) the Fourier transform and its inverse are:
- Given a continuous signal ``g(t)`` the Fourier transform and its inverse are:
```math
\hat{g}(f) \equiv \int_{-\infty}^\infty g(t) e^{-2\pi i f t} dt \quad g(t) \equiv \int_{-\infty}^\infty \hat{g}(f) e^{+2\pi i f t} df
......@@ -98,7 +98,7 @@ md"""
\mathcal{F}\{g\} = \hat{g} \quad \mathcal{F}^{-1}\{\hat{g}\} = g
```
- g and ĝ are know as a Fourier pair: $g \Longleftrightarrow \hat{g}$.
- ``g`` and ``ĝ`` are know as a Fourier pair: ``g \Longleftrightarrow \hat{g}``.
- The Fourier Transform (FT) is a linear operator:
......@@ -107,22 +107,22 @@ md"""
\mathcal{F}\{A f(t)\} = A\mathcal{F}\{f(t)\}
```
- The FT of a sinusoid with frequency $f_0$ is a sum of delta functions at $\pm f_0$, where $\delta(f)\equiv\int_{-\infty}^\infty e^{-2\pi i x f}df$.
- The FT of a sinusoid with frequency ``f_0`` is a sum of delta functions at ``\pm f_0``, where ``\delta(f)\equiv\int_{-\infty}^\infty e^{-2\pi i x f}df``.
- We can write: $ \mathcal{F}\{e^{2\pi f_0 t}\} = \delta(f - f_0)$, and:
- We can write: `` \mathcal{F}\{e^{2\pi f_0 t}\} = \delta(f - f_0)``, and:
```math
\mathcal{F}\{\cos(2\pi f_0 t)\} = \frac{1}{2}\left[\delta(f - f_0) + \delta(f + f_0)\right] \quad
\mathcal{F}\{\sin(2\pi f_0 t)\} = \frac{1}{2i}\left[\delta(f - f_0) - \delta(f + f_0)\right]
```
- Relations that can be derived from Euler’s formula: $e^{ix} = \cos x + i\sin x$
- Relations that can be derived from Euler’s formula: ``e^{ix} = \cos x + i\sin x``
- A time shift imparts a phase in the FT: $ \mathcal{F}\{g(t - t_0)\} = \mathcal{F}\{g(t)\} e^{-2\pi i ft_0}$.
- A time shift imparts a phase in the FT: `` \mathcal{F}\{g(t - t_0)\} = \mathcal{F}\{g(t)\} e^{-2\pi i ft_0}``.
- And, as we know, the squared amplitude of the FT of a continuous signal is known as the power spectral density (PSD): $ \mathcal{P}_g \equiv \left|\mathcal{F}\{g\}\right|^2 $.
- And, as we know, the squared amplitude of the FT of a continuous signal is known as the power spectral density (PSD): `` \mathcal{P}_g \equiv \left|\mathcal{F}\{g\}\right|^2 ``.
- Note that if $g$ is real-valued, it follows that $P_g$ is an even function, {i.e.} $\mathcal{P}_g(f) = \mathcal{P}_g(-f)$.
- Note that if ``g`` is real-valued, it follows that ``P_g`` is an even function, {i.e.} ``\mathcal{P}_g(f) = \mathcal{P}_g(-f)``.
$(LocalResource("Pics/FTpairs.png"))
"""
......@@ -709,7 +709,7 @@ md"""
# ╔═╡ 9d413d79-c9fb-4c30-ac02-92380510b607
# ╠═╡ show_logs = false
begin
fg6 = Figure(size=(2000,1000))
fg6 = Figure(size=(700,350))
ax1fg6 = Axis(fg6[1, 1],
title="Peak scaling with number of data points (fixed S/N=10)",
......@@ -837,7 +837,7 @@ begin
p99 = LombScargle.fapinv(lsboot7,0.99)
fg7 = Figure(size=(1000,400))
fg7 = Figure(size=(700,350))
ax1fg7 = Axis(fg7[1, 1],
)
......
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