我正在尝试在 TikZ 中绘制 DSB(抑制载波)频谱的频谱,如附图所示,或几乎像它一样。
下面的代码距离我很远。我很感激帮助弥补差距。
\documentclass[12pt]{book}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{graphicx}
\usepackage{epstopdf}
\usepackage{pgfplots}
\usepackage[american]{circuitikz}
\usepackage{caption}
\usepackage{subcaption}
\begin{document}
\begin{figure}
\centering
\pgfplotsset{
standard/.style={
axis x line=middle,
axis y line=middle,
enlarge x limits=0.25,
enlarge y limits=0.25, x label style={anchor=west},
y label style={anchor=south}
}
}
\begin{subfigure}[b]{\textwidth}
\centering
\begin{tikzpicture}
\begin{axis}[standard, scale = 1.2,
xlabel=$f$, ylabel=$M(f)$,
xtick={-2, 2}, ytick = {0.25},
xticklabels={$-B$,$B$},
yticklabels={1},
xmin = -10, xmax = 10,
ymin = 0, ymax = 0.4]
\addplot[ultra thick, black] coordinates {(-2,0)(0,0.25)(2,0)};
\end{axis}
\end{tikzpicture}
\caption{Baseband signal spectrum.}
\end{subfigure}
\vfill
\begin{subfigure}[b]{\textwidth}
\centering
\begin{tikzpicture}
\begin{axis}[standard, scale = 1.2,
xlabel=$f$, ylabel=$S(f)$,
xtick={-9, 9}, ytick = {0.125},
xticklabels={$-f_c$,$f_c$},
yticklabels={0.5},
xmin = -10, xmax = 10,
ymin = 0, ymax = 0.2]
\addplot[ultra thick, black] coordinates {(7,0)(9,0.125)(11,0)};
\addplot[ultra thick, black] coordinates {(-7,0)(-9,0.125)(-11,0)};
\end{axis}
\end{tikzpicture}
\caption{Passband signal spectrum.}
\end{subfigure}
\caption{DSB-SC signal spectrum.}
\label{fig:Sig-time-scaling}
\end{figure}
\end{document}
答案1
\documentclass[tikz,border=3.14159mm]{standalone}
\newcommand{\DSB}[1]{
\def\xa{3} \def\ya{0}
\def\xb{1} \def\yb{2}
\def\xc{0} \def\yc{1.7}
\def\tang{.4}
%
\def\curve{
(#1-\xa,\ya) .. controls ++ (2*\tang,0) and ++ (-\tang,0) ..
(#1-\xb,\yb) .. controls ++ (.5*\tang,0) and ++ (-\tang,0) ..
(#1,\yc) .. controls ++ (\tang,0) and ++ (-.5*\tang,0) ..
(#1+\xb,\yb) .. controls ++ (\tang,0) and ++ (-2*\tang,0) ..
(#1+\xa,\ya)
}
\path[fill=violet!40] (#1-\xa,0) -- \curve -- (#1+\xa,0) -- cycle;
\draw \curve;
}
\begin{document}
\begin{tikzpicture}[
line width=1pt,
sb/.style={text width=1.5cm, align=center,inner sep=0pt}]
\DSB{0}
\draw (-10,0) -- (10,0) node [below left] {$f \longrightarrow$}
(0,0) node[below] {0} --++ (0,3) node [below right] {$M(f)$};
\path (-3,0) node[below] {$-B$} -- (3,0) node[below] {$B$};
\node[left] at (10,.5) {(a) Baseband};
\begin{scope}[yshift=-5cm]
\def\xs{5}
\DSB{-\xs} \DSB{\xs}
\draw (-10,0) -- (10,0) node [below left] {$f \longrightarrow$}
(0,0) node[below] {0} --++ (0,3)
(-\xs,0) node[below] {$-f_C$} --++ (0,2.5)
(\xs,0) node[below] {$f_C$} --++ (0,2.5);
\node[left] at (10,.5) {(b) DSB};
\draw[stealth-] (-\xs-1.5,1.5) to [bend right] ++ (-1,.5) node[left,sb] {Upper sideband};
\draw[stealth-] (-\xs+1.5,1.5) to [bend left] ++ (1,.5) node[right,sb] {Lower sideband};
\draw[stealth-] (\xs-1.5,1.5) to [bend right] ++ (-1,.5) node[left,sb] {Lower sideband};
\draw[stealth-] (\xs+1.5,1.5) to [bend left] ++ (1,.5) node[right,sb] {Upper sideband};
\end{scope}
\end{tikzpicture}
\end{document}