LaTeX forum ⇒ Graphics, Figures & Tables ⇒ Sketching a block diagram
Sketching a block diagram
Can anybody help me with sketching the echo cancellation block diagram as shown below (The microphone and speaker icons are just a sample shape and does not have to be the same in the figure. Just a general icon is fine for both of them!)! thanks.
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 Fig4.22__Page_1.png (70.78 KiB) Viewed 2220 times
 Stefan Kottwitz
 Site Admin
 Posts: 9593
 Joined: Mon Mar 10, 2008 9:44 pm
Hi,
I saw the same question on TeX.SE by the way. Crossposts are ok when they have links to each other.
Well, what is the actual problem? What code do you have already, where is it stuck?
Stefan
I saw the same question on TeX.SE by the way. Crossposts are ok when they have links to each other.
Well, what is the actual problem? What code do you have already, where is it stuck?
Stefan
LaTeX.org admin
Dear Stephen,
Sure, i will note about the link. I did delete the question 3 hours ago from textse and should not be longer existed!! Honestly, I don't have any code because i'm very new to Tikz. I know it may be improper for me to ask but i would be appreciate if you can help on Sketching the block diagram as shown in the figure. Many Thanks
Sure, i will note about the link. I did delete the question 3 hours ago from textse and should not be longer existed!! Honestly, I don't have any code because i'm very new to Tikz. I know it may be improper for me to ask but i would be appreciate if you can help on Sketching the block diagram as shown in the figure. Many Thanks
 Stefan Kottwitz
 Site Admin
 Posts: 9593
 Joined: Mon Mar 10, 2008 9:44 pm
Here is a quick code to get you started:
Stefan
\documentclass[border=10pt]{standalone} \usepackage{tikz} \usetikzlibrary{positioning,quotes,calc} \begin{document} \begin{tikzpicture}[>=latex] \node [rectangle, draw, inner sep = 8pt] (center) {wk}; \node [circle, draw, , inner sep = 1pt, below = 0.8cm of center] (bottom) {+}; \coordinate [above = 0.8cm of center] (top); \node [left = 2.5cm of bottom, "below:To Far End"] (bottom left) {}; \node [right = 2.5cm of bottom, "below:Near End Speech"] (bottom right) {}; \node [left = 2.5cm of top, "Far End Speech"] (top left) {}; \coordinate [right = 2.5cm of top] (top right); \draw [>] (bottom)  (bottom left); \draw [>] (bottom right)  (bottom); \draw [>] (center)  (bottom); \draw [>] (top)  (center); \draw (top left)  (top); \draw [>] (top)  (top right); \draw [densely dashed] ($(bottom)(1,0.3)$)  ($(top)(1,0.3)$)  ($(top)+(1,0.3)$)  ($(bottom)+(1,0.3)$)  cycle; \end{tikzpicture} \end{document}
Stefan
LaTeX.org admin
Thank you very much indeed. It was a great help/

 Posts: 2
 Joined: Tue Jul 07, 2020 10:39 am
Does {tikz} package work on TEXMAKER and Texstudio?
I am using it but unable to get the output.
I am using it but unable to get the output.
 Ijon Tichy
 Posts: 295
 Joined: Mon Dec 24, 2018 10:12 am
nishant_er07 wrote:Does {tikz} package work on TEXMAKER and Texstudio?
I am using it but unable to get the output.
TeXmaker and TeXstudio are only editors. TikZ does work with all TeX distributions and is available as packages for MiKTeX and TeX Live and derived TeX distributions like MacTeX via the package manager of the distribution.
If you don't have an output, have a look into the logfile (or at least the error output of your editor). Maybe the package is not installed or you've another error. And maybe then it would be better to ask a new question about that error, if you cannot already find a similar one.

 Posts: 2
 Joined: Tue Jul 07, 2020 10:39 am
Thank you for the response. I am a beginner in LATEX. I have learnt just a few things and trying it by just typing a sample article. In my article, I am trying to draw a block diagram after text in a subsection. I am trying it using tikz package.
The script is shared below. I am running this script with INTERNET OFF, getting the errors as :
! Package pgf Error: No shape named `Npoint FFT' is known.See the pgf package documentation for explanation.Type H <return> for immediate help....
! Package tikz Error: Giving up on this path. Did you forget a semicolon?.See the tikz package documentation for explanation.Type H <return> for immediate help.... \end{tikzpicture}
! Undefined control sequence.<argument> \pgf@baseline \end{tikzpicture}
With the INTERNET ON, Neither Error nor Output is being displayed.
I am looking for some assistance please.
Script:
\documentclass[10pt,onecolumn,a4paper]{article}
\linespread{1.5}
\title{PAPR reduction and nonlinearity alleviation using hybrid of precoding and companding in a visible light communication (VLC) system}
%\author{Nishant Sharan\\S.K Ghorai}
\usepackage{amssymb,amsmath}
\usepackage{graphicx} % dvips destroys the tikzpicture to a mess
\usepackage{tikz}
\usetikzlibrary{shapes.geometric,arrows}
\tikzstyle{startstop} = [rectangle, rounded corners, text centered, draw=black, fill=blue!10]
\tikzstyle{process} = [rectangle, minimum width=2cm, minimum height=1cm, text centered, draw=black, fill=orange!10]
\tikzstyle{decision} = [diamond, aspect=3, minimum width=3cm, minimum height=1cm, text centered, draw=black, fill=red!10]
% define arrow style
\tikzstyle{compute} = [rectangle, minimum width=2cm, minimum height=1cm, text centered, draw=black, fill=green!10]
\tikzstyle{estimate} = [rectangle, rounded corners, minimum width=2cm, minimum height=1cm, text centered, draw=black, fill=yellow!10]
\tikzstyle{arrow} = [thick,>,>=stealth]
\tikzstyle{block}=[draw,rectangle,node distance=8em]
\begin {document}
%\begin{flushleft}
\maketitle
\section*{Abstract}A hybrid technique using a precoder and a $\mu$ law compander is proposed to alleviate light emitting diode(LED) nonlinearity as well as peakto average power ratio (PAPR) reduction in a VLC system.A $\mu$ law compander is used to compress the peak valued signal and enhances small amplitudes to lower the PAPR. The work attains optimal PAPR and improves bit error rate (BER) of the system at low signal to noise values. The nonlinear characteristic of a LED used as the transmitter in a VLC system leads to damaging effect whiole using OFDM in an optical system. The combination scheme improves LED nonlinearity for low input backoff power(IBO). In the work,nonlinearity is characterised using error vector magnitude (EVM) in percentage. The proposed method shows a 5 $\%$ EVM improvement for 0dB IBO.The paper provides a choice for a tradeoff among PAPR reduction,BER and reduced nonlinearity.
\section*{Keywords}OFDM,VLC,PAPR,Precodeing,Companding,BER
\section{Introduction}
The highspeed wireless services such as high definition(HD)video and picture transmission, internet protocol (IP) based voice calls,online games and videos,ecommerce transactions,etc urge for the fast speed mobile data network.
\section{Optical Modulation Schemes}
In this section,conventional ACOOFDM,PAMDMT and DCOOFDM schemes as well as hybrid modulation schemes such as HACOOFDM,ADOOFDM and LACOOFDM are described.
\subsection{Conventional Schemes}
\subsubsection{ACOOFDM}In ACOOFDM,only the odd subcarriers carry data while the even sub carriers are set to zeros in the frequency domain.The input signal to the \textit{N}point IFFT,\textbf{X},consists of only odd components and satisfies the Hermitian symmetry as \textbf{X}=[0,X\textsubscript{1},0,X\textsubscript{3}.....,X\textsubscript{N/21},0,X\textsuperscript{*}\textsubscript{N/21}....,X\textsubscript{3},X\textsubscript{1}].The timedomain signal x\textsubscript{n} has the antisymmetric property as x\textsubscript{n}= x\textsubscript{n+N/2},(0$\leq$ n\textless N/2).The ACOOFDM signal, x\textsubscript{ACO,n},is ensured nonnegative by clipping the negative part without losing any information as
\begin{equation}
\
x_{Aco,n}=
\begin{cases} x_{n}, &\text{ $x_{n} \geq 0$,}\\
\ 0, &\text{ $ x_{n} < 0$.}\\
\end{cases}
\
\end{equation}
In [11], it has been proved that the clipping noise only falls on the even subcarriers,which will not affect the demodulation of the transmitted data.
\subsubsection{PAMDMT:}In PAMDMT, signals drawn from PAM are used to modulate the imaginary part of each subcarrier except the 0th and N/2th subcarriers. The input to the IFFT block can be represented as
$\textbf{Y}=0,Y_{1},Y_{2},\ldots,Y_{N/21},0,Y^*_{n/21},\ldots,Y^*_{1}$,
where $Y_{k}=ib_{k},b_{k}(k=1,2,\ldots,N/21)$ is the real valued PAM signal and $i^2=1$. As shown in [15], the time domain signal $y_{n}$ follows the symmetry as $y_{n}=Y_{Nn},(0\leqslant n < N/2)$.Therefore, PAMDMT signal $y_{PAM,n}$ can be clipped at zero without any loss of information as
\begin{equation}
\
y_{PAM,n}=
\begin{cases} y_{n}, &\text{ $y_{n} \geq 0$,}\\
\ 0, &\text{ $ y_{n} < 0$.}\\
\end{cases}
\
\end{equation}
\subsubsection{DCOOFDM:}In DCOOFDM,the signal $Z_{n}$ is generated by the IFFT is guaranteed is guaranteed to be positive by adding a DC bias, $B_{Dc}$. After the superposition, the remaining negative signal will be clipped at zero, leading to a clipping noise,c\textsubscript{n} which depends on DC bias. Then the transmitted DCOFDM signal $Z_{DCO,n}$ is given by
\begin{equation}
Z_{DCO,n}=
z_{n}+B_{DC}+C_{n}.
\end{equation}
Moreover, $B_{DC}$ is usually relative to the electrical power of the signal $z_{n}$, and $B_{DC}=\mu\sqrt{E{Z_{n}^2}}$,where $\mu$ is a proportional constant and $B_{DC}$ is defined as 10log\textsubscript{10}$(\mu^2+1)$ dB.
\subsection{Hybrid Schemes}
Figs.1 and 2 illustrate the transmitters and receivers of HACOOFDM, ADOOFDM and LACOOFDM, respectively.
%\begin{figure}\centering
%the \par is necessary after each text to make the \baselineskip take effect
\begin{tikzpicture}[node distance=1.5cm, auto]
\node (start) [block] {Npoint FFT};
\node[block,right of= Npoint FFT](process1){Process1}
\end{tikzpicture}
%\caption{Block diagram of Alfvenic aurora detection algorithm.}
\label{fig:blockcv}
%\end{figure}
\end {document}
The script is shared below. I am running this script with INTERNET OFF, getting the errors as :
! Package pgf Error: No shape named `Npoint FFT' is known.See the pgf package documentation for explanation.Type H <return> for immediate help....
! Package tikz Error: Giving up on this path. Did you forget a semicolon?.See the tikz package documentation for explanation.Type H <return> for immediate help.... \end{tikzpicture}
! Undefined control sequence.<argument> \pgf@baseline \end{tikzpicture}
With the INTERNET ON, Neither Error nor Output is being displayed.
I am looking for some assistance please.
Script:
\documentclass[10pt,onecolumn,a4paper]{article}
\linespread{1.5}
\title{PAPR reduction and nonlinearity alleviation using hybrid of precoding and companding in a visible light communication (VLC) system}
%\author{Nishant Sharan\\S.K Ghorai}
\usepackage{amssymb,amsmath}
\usepackage{graphicx} % dvips destroys the tikzpicture to a mess
\usepackage{tikz}
\usetikzlibrary{shapes.geometric,arrows}
\tikzstyle{startstop} = [rectangle, rounded corners, text centered, draw=black, fill=blue!10]
\tikzstyle{process} = [rectangle, minimum width=2cm, minimum height=1cm, text centered, draw=black, fill=orange!10]
\tikzstyle{decision} = [diamond, aspect=3, minimum width=3cm, minimum height=1cm, text centered, draw=black, fill=red!10]
% define arrow style
\tikzstyle{compute} = [rectangle, minimum width=2cm, minimum height=1cm, text centered, draw=black, fill=green!10]
\tikzstyle{estimate} = [rectangle, rounded corners, minimum width=2cm, minimum height=1cm, text centered, draw=black, fill=yellow!10]
\tikzstyle{arrow} = [thick,>,>=stealth]
\tikzstyle{block}=[draw,rectangle,node distance=8em]
\begin {document}
%\begin{flushleft}
\maketitle
\section*{Abstract}A hybrid technique using a precoder and a $\mu$ law compander is proposed to alleviate light emitting diode(LED) nonlinearity as well as peakto average power ratio (PAPR) reduction in a VLC system.A $\mu$ law compander is used to compress the peak valued signal and enhances small amplitudes to lower the PAPR. The work attains optimal PAPR and improves bit error rate (BER) of the system at low signal to noise values. The nonlinear characteristic of a LED used as the transmitter in a VLC system leads to damaging effect whiole using OFDM in an optical system. The combination scheme improves LED nonlinearity for low input backoff power(IBO). In the work,nonlinearity is characterised using error vector magnitude (EVM) in percentage. The proposed method shows a 5 $\%$ EVM improvement for 0dB IBO.The paper provides a choice for a tradeoff among PAPR reduction,BER and reduced nonlinearity.
\section*{Keywords}OFDM,VLC,PAPR,Precodeing,Companding,BER
\section{Introduction}
The highspeed wireless services such as high definition(HD)video and picture transmission, internet protocol (IP) based voice calls,online games and videos,ecommerce transactions,etc urge for the fast speed mobile data network.
\section{Optical Modulation Schemes}
In this section,conventional ACOOFDM,PAMDMT and DCOOFDM schemes as well as hybrid modulation schemes such as HACOOFDM,ADOOFDM and LACOOFDM are described.
\subsection{Conventional Schemes}
\subsubsection{ACOOFDM}In ACOOFDM,only the odd subcarriers carry data while the even sub carriers are set to zeros in the frequency domain.The input signal to the \textit{N}point IFFT,\textbf{X},consists of only odd components and satisfies the Hermitian symmetry as \textbf{X}=[0,X\textsubscript{1},0,X\textsubscript{3}.....,X\textsubscript{N/21},0,X\textsuperscript{*}\textsubscript{N/21}....,X\textsubscript{3},X\textsubscript{1}].The timedomain signal x\textsubscript{n} has the antisymmetric property as x\textsubscript{n}= x\textsubscript{n+N/2},(0$\leq$ n\textless N/2).The ACOOFDM signal, x\textsubscript{ACO,n},is ensured nonnegative by clipping the negative part without losing any information as
\begin{equation}
\
x_{Aco,n}=
\begin{cases} x_{n}, &\text{ $x_{n} \geq 0$,}\\
\ 0, &\text{ $ x_{n} < 0$.}\\
\end{cases}
\
\end{equation}
In [11], it has been proved that the clipping noise only falls on the even subcarriers,which will not affect the demodulation of the transmitted data.
\subsubsection{PAMDMT:}In PAMDMT, signals drawn from PAM are used to modulate the imaginary part of each subcarrier except the 0th and N/2th subcarriers. The input to the IFFT block can be represented as
$\textbf{Y}=0,Y_{1},Y_{2},\ldots,Y_{N/21},0,Y^*_{n/21},\ldots,Y^*_{1}$,
where $Y_{k}=ib_{k},b_{k}(k=1,2,\ldots,N/21)$ is the real valued PAM signal and $i^2=1$. As shown in [15], the time domain signal $y_{n}$ follows the symmetry as $y_{n}=Y_{Nn},(0\leqslant n < N/2)$.Therefore, PAMDMT signal $y_{PAM,n}$ can be clipped at zero without any loss of information as
\begin{equation}
\
y_{PAM,n}=
\begin{cases} y_{n}, &\text{ $y_{n} \geq 0$,}\\
\ 0, &\text{ $ y_{n} < 0$.}\\
\end{cases}
\
\end{equation}
\subsubsection{DCOOFDM:}In DCOOFDM,the signal $Z_{n}$ is generated by the IFFT is guaranteed is guaranteed to be positive by adding a DC bias, $B_{Dc}$. After the superposition, the remaining negative signal will be clipped at zero, leading to a clipping noise,c\textsubscript{n} which depends on DC bias. Then the transmitted DCOFDM signal $Z_{DCO,n}$ is given by
\begin{equation}
Z_{DCO,n}=
z_{n}+B_{DC}+C_{n}.
\end{equation}
Moreover, $B_{DC}$ is usually relative to the electrical power of the signal $z_{n}$, and $B_{DC}=\mu\sqrt{E{Z_{n}^2}}$,where $\mu$ is a proportional constant and $B_{DC}$ is defined as 10log\textsubscript{10}$(\mu^2+1)$ dB.
\subsection{Hybrid Schemes}
Figs.1 and 2 illustrate the transmitters and receivers of HACOOFDM, ADOOFDM and LACOOFDM, respectively.
%\begin{figure}\centering
%the \par is necessary after each text to make the \baselineskip take effect
\begin{tikzpicture}[node distance=1.5cm, auto]
\node (start) [block] {Npoint FFT};
\node[block,right of= Npoint FFT](process1){Process1}
\end{tikzpicture}
%\caption{Block diagram of Alfvenic aurora detection algorithm.}
\label{fig:blockcv}
%\end{figure}
\end {document}
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