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Write base and broad band for com num

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communications-numeriques/main.tex
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@ -118,25 +118,33 @@
\subsection{Système de transmission en bande de base (\emph{base band})}
Le signal est directement transmis sur le canal de transmission.
Son spectre est centré sur la fréquence 0.
Les câbles sont les canaux de transmission possibles (paire torsadée, câble coaxial, paire avec écran\ldots).
% TODO: add schéma de système de transmission de bande de base
\begin{center}
\begin{tikzpicture}[scale=0.8, transform shape]
\node [ellipse,draw] (source) at (0,0) {Source};
\node [rectangle,draw] (c) at (3,0) [label=below:Chiffrement] {C};
\node [rectangle,draw] (r) at (6,0) [label=below:Compression] {R};
\node [rectangle,draw] (e) at (9,0) [label=below:\parbox{2cm}{\centering Encodage\\Détecteur\\Correcteur\\d'erreurs}] {E};
\node [rectangle,draw] (b) at (12,0) [label=below:Embrouillage] {B};
\node [rectangle,draw] (v) at (15,0) [label=right:Codage numérique] {V};
\node [rectangle,fill=olive!40] at (4.5,1.5) {Codage de source};
\node [rectangle,fill=olive!40,minimum width=5.5cm,minimum height=1.7cm] at (4.5,0) {};
\node [rectangle,draw,fill=white,minimum width=1.5cm] (c) at (3,0) [label=below:Chiffrement] {C};
\node [rectangle,draw,fill=white,minimum width=1.5cm] (r) at (6,0) [label=below:Compression] {R};
\node [rectangle,fill=blue!30] at (12,1.5) {Codage du canal};
\node [rectangle,fill=blue!30,minimum width=8.5cm,minimum height=1.7cm] at (12,0) {};
\node [rectangle,draw,fill=white,minimum width=1.5cm] (e) at (9,0) [label=below:\parbox{2cm}{\centering Encodage\\Détecteur\\Correcteur\\d'erreurs}] {E};
\node [rectangle,draw,fill=white,minimum width=1.5cm] (b) at (12,0) [label=below:Embrouillage] {B};
\node [rectangle,draw,fill=white,minimum width=1.5cm] (v) at (15,0) [label=right:\parbox{2cm}{Codage\\numérique}] {V};
\node [diamond,draw] (canal) at (15,-3) {canal};
\node [diamond,draw] (h1) at (13,-5.5) [label=left:Regénération] {H--1};
\node [rectangle,draw] (v1) at (15,-6) [label=right:Décodage numérique] {V--1};
\node [rectangle,draw] (b1) at (12,-6) [label=below:Désembrouillage] {B--1};
\node [rectangle,draw] (e1) at (9,-6) {E--1};
\node [rectangle,draw] (r1) at (6,-6) [label=below:Décompression] {R--1};
\node [rectangle,draw] (c1) at (3,-6) [label=below:Déchiffrement] {C--1};
\node [ellipse,draw] (utilisation) at (-1,-6) {Utilisation};
\node [rectangle,draw,minimum width=1.5cm] (v1) at (15,-8) [label=right:\parbox{2cm}{Décodage\\numérique}] {V--1};
\node [rectangle,draw,minimum width=1.5cm] (b1) at (12,-8) [label=below:Désembrouillage] {B--1};
\node [rectangle,draw,minimum width=1.5cm] (e1) at (9,-8) [label=below:\parbox{2cm}{\centering Détection et Correction des erreurs}] {E--1};
\node [rectangle,draw,minimum width=1.5cm] (r1) at (6,-8) [label=below:Décompression] {R--1};
\node [rectangle,draw,minimum width=1.5cm] (c1) at (3,-8) [label=below:Déchiffrement] {C--1};
\node [ellipse,draw] (utilisation) at (-1,-8) {Utilisation};
\draw [-latex] (source) -- (c) node[above, midway]{$\{sk\}$};
\draw [-latex] (c) -- (r) node[above, midway]{$\{dk\}$};
@ -147,6 +155,14 @@
\draw [-latex] (v) -- (canal) node[right, midway]{$e(t)$};
\draw [-latex] (canal) -- (v1) node[right, midway]{$r(t)$};
\draw [-latex] (15,-4.2) -- (13,-4.2) -- (h1);
\draw [-latex] (h1) -- (13,-7) -- (-1,-7) -- (utilisation);
\draw [-latex] (13,-7) -- (14.3,-7) -- (v1);
\draw [-latex] (12,-7) -- (b1);
\draw [-latex] (9,-7) -- (e1);
\draw [-latex] (6,-7) -- (r1);
\draw [-latex] (3,-7) -- (c1);
\draw [-latex] (v1) -- (b1) node[above, midway]{\{$\alpha k_e$\}};
\draw [-latex] (b1) -- (e1) node[above, midway]{$\{bk_e\}$};
\draw [-latex] (e1) -- (r1) node[above, midway]{$\{ck_e\}$};
@ -157,6 +173,70 @@
\subsection{Système de transmission en bande transposée (\emph{broad band})}
Le signal est modulé avant d'être transmis sur le canal de transmission.
Son spectre est centré sur la fréquence porteuse.
Les canaux de transmission possibles sont~:
\begin{itemize}
\item câbles
\item transmission hertzienne sans fil en espace libre
\item transmission optique en espace libre (infra rouge)
\item transmission optique guidée (fibre optique)
\end{itemize}
\begin{center}
\begin{tikzpicture}[scale=0.8, transform shape]
\node [ellipse,draw] (source) at (0,0) {Source};
\node [rectangle,fill=olive!40] at (4.5,1.5) {Codage de source};
\node [rectangle,fill=olive!40,minimum width=5.5cm,minimum height=1.7cm] at (4.5,0) {};
\node [rectangle,draw,fill=white,minimum width=1.5cm] (c) at (3,0) [label=below:Chiffrement] {C};
\node [rectangle,draw,fill=white,minimum width=1.5cm] (r) at (6,0) [label=below:Compression] {R};
\node [rectangle,fill=blue!30] at (12,1.5) {Codage du canal};
\node [rectangle,fill=blue!30,minimum width=8.5cm,minimum height=1.7cm] at (12,0) {};
\node [rectangle,draw,fill=white,minimum width=1.5cm] (e) at (9,0) [label=below:\parbox{2cm}{\centering Encodage\\Détecteur\\Correcteur\\d'erreurs}] {E};
\node [rectangle,draw,fill=white,minimum width=1.5cm] (b) at (12,0) [label=below:Embrouillage] {B};
\node [rectangle,draw,fill=white,minimum width=1.5cm] (v) at (15,0) [label=right:\parbox{2cm}{Codage\\numérique}] {V};
\node [rectangle,red,draw,minimum width=1.5cm] [label={[text=red]left:\parbox{2cm}{\centering Modulation\\numérique}},label={[text=red]right:$x(t)$}] (l) at (15,-2.5) {L};
\node [diamond,draw] (canal) at (15,-5) {canal};
\node [rectangle,red,draw,minimum width=1.5cm] [label={[text=red]left:\parbox{2.5cm}{\centering Démodulation\\numérique}},label={[text=red]right:$x(t)_e$}] (l1) at (15,-7.5) {L--1};
\node [diamond,draw] (h1) at (13,-9.5) [label=left:Regénération] {H--1};
\node [rectangle,draw,minimum width=1.5cm] (v1) at (15,-12) [label=right:\parbox{2cm}{Décodage\\numérique}] {V--1};
\node [rectangle,draw,minimum width=1.5cm] (b1) at (12,-12) [label=below:Désembrouillage] {B--1};
\node [rectangle,draw,minimum width=1.5cm] (e1) at (9,-12) [label=below:\parbox{2cm}{\centering Détection et Correction des erreurs}] {E--1};
\node [rectangle,draw,minimum width=1.5cm] (r1) at (6,-12) [label=below:Décompression] {R--1};
\node [rectangle,draw,minimum width=1.5cm] (c1) at (3,-12) [label=below:Déchiffrement] {C--1};
\node [ellipse,draw] (utilisation) at (-1,-12) {Utilisation};
\draw [-latex] (source) -- (c) node[above, midway]{$\{sk\}$};
\draw [-latex] (c) -- (r) node[above, midway]{$\{dk\}$};
\draw [-latex] (r) -- (e) node[above, midway]{$\{ck\}$};
\draw [-latex] (e) -- (b) node[above, midway]{$\{bk\}$};
\draw [-latex] (b) -- (v) node[above, midway]{$\{\alpha k\}$};
\draw [-latex] (v) -- (l);
\draw [-latex] (l) -- (canal) node[right, midway]{$e(t)$};
\draw [-latex] (canal) -- (l1) node[right, midway]{$r(t)$};
\draw [-latex] (l1) -- (v1);
\draw [-latex] (15,-8.2) -- (13,-8.2) -- (h1);
\draw [-latex] (h1) -- (13,-11) -- (-1,-11) -- (utilisation);
\draw [-latex] (13,-11) -- (14.3,-11) -- (v1);
\draw [-latex] (12,-11) -- (b1);
\draw [-latex] (9,-11) -- (e1);
\draw [-latex] (6,-11) -- (r1);
\draw [-latex] (3,-11) -- (c1);
\draw [-latex] (v1) -- (b1) node[above, midway]{\{$\alpha k_e$\}};
\draw [-latex] (b1) -- (e1) node[above, midway]{$\{bk_e\}$};
\draw [-latex] (e1) -- (r1) node[above, midway]{$\{ck_e\}$};
\draw [-latex] (r1) -- (c1) node[above, midway]{$\{dk_e\}$};
\draw [-latex] (c1) -- (utilisation) node[above, midway]{$\{sk_e\}$};
\end{tikzpicture}
\end{center}
\subsection{Intérêt de la transmission numérique}
Le passage du signal dans un canal qui est déformant (filtrage) et bruyant est un problème de la transmission analogique.