Thesis: remove HilbertTiming + small random fixes

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Eric-Teunis de Boone 2023-11-06 13:55:06 +01:00
parent 3fc1a48e64
commit cc1657e893
4 changed files with 4 additions and 40 deletions

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@ -59,10 +59,6 @@ The detection and identification of more complex time-domain signals can be achi
which is the basis for the pulsed beacon method of Section~\ref{sec:beacon:pulse}.
\\
%\section{Analysis Methods}% <<<
%\label{sec:waveform:analysis}
\section{Fourier Transforms}% <<<<
\label{sec:fourier}
The \gls{FT} allows for a frequency-domain representation of a time-domain signal.
@ -126,7 +122,6 @@ Implementing the above decomposition of $t[n]$, \eqref{eq:fourier:dtft} can be r
The direct computation of this transform takes $2N$ complex multiplications and $2(N-1)$ complex additions for a single frequency $k$.
When computing this transform for all integer $0 \leq k < N$, this amounts to $\mathcal{O}(N^2)$ complex computations.
\acrlong{FFT}s (\acrshort{FFT}s) are efficient algorithms that derive all $X( 0 \leq k < N)$ in $\mathcal{O}( N \log N)$ calculations.
%For integer $0 \leq k < N $, efficient algorithms exist that derive all $X( 0 \leq k < N )$ in $\mathcal{O}( N \log N )$ calculations instead of $\mathcal{O}(kcalled \acrlong{FFT}s, sampling a subset of the frequencies.\Todo{citation?}
\begin{figure}
\begin{subfigure}{0.49\textwidth}
@ -226,7 +221,6 @@ opening the way to efficiently measuring the phases in realtime.
% >>>>
%\section{Pulse Detection}
\section{Cross-Correlation}% <<<<
\label{sec:correlation}
@ -286,34 +280,5 @@ This allows to approximate an analog time delay between two waveforms when one w
\label{fig:correlation}
\end{figure}
% >>>
\section{Hilbert Transform}% <<<<
\Todo{remove section?}
The analytic signal $s_a(t)$ of a waveform $x(t)$ can be obtained using the Hilbert Transform through
\begin{equation}
\label{eq:analytic_signal}
\phantom{,}
s_a(t) = x(t) + \hat{x}(t)
,
\end{equation}
where $\hat{x}(t)$ is the Hilbert Transformed waveform.
The Hilbert Transform corresponds to a \gls{FT} where positive frequencies are phase-shifted by $-\pi/2$ and negative frequencies are phase-shifted by $+\pi/2$.
\\
The analytic signal allows to estimate the overall maximum amplitude of a signal irrespective of sign by determining its envelope.
In Figure~\ref{fig:hilbert_transform}, the envelope of a signal is used to find the time of the maximum amplitude.
Such a mechanism might be used for timing instead of the cross-correlation described in the previous Section.
\\
\begin{figure}
\centering
\includegraphics[width=0.5\textwidth]{pulse/hilbert_timing_interpolation_template.pdf}
\caption{
Timing information from the maximum amplitude of the envelope.
\protect \Todo{noisy trace figure}
}
\label{fig:hilbert_transform}
\end{figure}
% >>>>
% >>>
\end{document}