% Author: Dr. Matthias Jung, DL9MJ
% Year: 2022
\begin{filecontents*}{sql.csv}
    a, b
    0,4.5
    1,4.3
    2,4.5
    3,4.2
    4,3.8
    5,4.5
    6,4.2
    7,4.0
    8,14
    9,10
    10,15
    11,9
    12,16
    13,11
    14,16
    15,10
    16,15
    17,9
    18,16
    19,9
    20,16
    21,4.5
    22,5
    23,4.2
    24,3.8
    25,4.5
    26,4.2
    27,4.5
    28,5
    29,4.2
    30,3.8
    31,4.5
    32,4.2
    33,4.5
    34,5
    35,4.2
    36,3.8
    37,4
    38,7
    39,5
    40,8
    41,5
    42,8
    43,6
    44,8
    45,6
    46,8
    47,5
    48,8
    49,6
    50,8
    51,4.5
    52,4.5
    53,4.2
    54,3.8
    55,4.5
    56,4.2
    57,4.3
    58,4.2
    59,4.4
    60,4.1
\end{filecontents*}

\pgfkeys{/pgf/number format/.cd,1000 sep={}}
\begin{tikzpicture}
    \begin{axis}[
        axis lines=center, 
        axis line style={-Triangle},
        width=\linewidth,
        height=6cm,
        xmin=0,
        xmax=60,
        ymin=0,
        ymax=20,
        ticks=none,
        xlabel={$t$},
        xlabel style={anchor=north},
        ylabel={$U$},
        ylabel style={anchor=east},
    ]
        \addplot[smooth, draw=DARCblue, thick] table [x=a, y=b, col sep=comma] {sql.csv};
        \addplot[mark=none, DARCorange, samples=2, thick, dashed, domain=0:60] {8.1};

        \draw[DARCblue](axis cs: 14,18) node[](){Starkes Signal};
        \draw[DARCblue](axis cs: 30,2) node[](){Rauschen};
        \draw[DARCblue](axis cs: 45,10) node[](){Schwaches Signal};
        \draw[DARCorange](axis cs: 30,8.1) node[anchor=north](){Squelch};
    \end{axis}
\end{tikzpicture}