## LaTeX forum ⇒ Graphics, Figures & Tables ⇒ Sketching a block diagram

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feryee
Posts: 20
Joined: Sun Aug 09, 2015 12:57 pm

### 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.
Attachments
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
LaTeX.org admin

feryee
Posts: 20
Joined: Sun Aug 09, 2015 12:57 pm
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

Stefan Kottwitz
Site Admin
Posts: 9593
Joined: Mon Mar 10, 2008 9:44 pm
Here is a quick code to get you started:

Code: [Select all] [Expand/Collapse] [Download] ({untitled.tex})
\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

feryee
Posts: 20
Joined: Sun Aug 09, 2015 12:57 pm
Thank you very much indeed. It was a great help/

nishant_er07
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.

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 log-file (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.

nishant_er07
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 `N-point 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 non-linearity 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) non-linearity as well as peak-to 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 non-linear 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 non-linearity for low input backoff power(IBO). In the work,non-linearity 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 trade-off among PAPR reduction,BER and reduced non-linearity.
\section*{Keywords}OFDM,VLC,PAPR,Precodeing,Companding,BER
\section{Introduction}
The high-speed wireless services such as high definition(HD)video and picture transmission, internet protocol (IP) based voice calls,online games and videos,e-commerce transactions,etc urge for the fast speed mobile data network.
\section{Optical Modulation Schemes}
In this section,conventional ACO-OFDM,PAM-DMT and DCO-OFDM schemes as well as hybrid modulation schemes such as HACO-OFDM,ADO-OFDM and LACO-OFDM are described.
\subsection{Conventional Schemes}
\subsubsection{ACO-OFDM}In ACO-OFDM,only the odd sub-carriers 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/2-1},0,X\textsuperscript{*}\textsubscript{N/2-1}....,X\textsubscript{3},X\textsubscript{1}].The time-domain signal x\textsubscript{n} has the antisymmetric property as x\textsubscript{n}= -x\textsubscript{n+N/2},(0$\leq$ n\textless N/2).The ACO-OFDM signal, x\textsubscript{ACO,n},is ensured non-negative by clipping the negative part without losing any information as

\
x_{Aco,n}=
\begin{cases} x_{n}, &\text{ $x_{n} \geq 0$,}\\
\ 0, &\text{ $x_{n} < 0$.}\\
\end{cases}
\

In [11], it has been proved that the clipping noise only falls on the even sub-carriers,which will not affect the demodulation of the transmitted data.
\subsubsection{PAM-DMT:}In PAM-DMT, signals drawn from PAM are used to modulate the imaginary part of each sub-carrier except the 0-th and N/2-th sub-carriers. The input to the IFFT block can be represented as
$\textbf{Y}=0,Y_{1},Y_{2},\ldots,Y_{N/2-1},0,Y^*_{n/2-1},\ldots,Y^*_{1}$,
where $Y_{k}=ib_{k},b_{k}(k=1,2,\ldots,N/2-1)$ is the real valued PAM signal and $i^2=-1$. As shown in [15], the time domain signal $y_{n}$ follows the symmetry as $y_{n}=-Y_{N-n},(0\leqslant n < N/2)$.Therefore, PAM-DMT signal $y_{PAM,n}$ can be clipped at zero without any loss of information as

\
y_{PAM,n}=
\begin{cases} y_{n}, &\text{ $y_{n} \geq 0$,}\\
\ 0, &\text{ $y_{n} < 0$.}\\
\end{cases}
\

\subsubsection{DCO-OFDM:}In DCO-OFDM,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 DC-OFDM signal $Z_{DCO,n}$ is given by

Z_{DCO,n}=
z_{n}+B_{DC}+C_{n}.

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 HACO-OFDM, ADO-OFDM and LACO-OFDM, 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] {N-point FFT};
\node[block,right of= N-point FFT](process1){Process1}

\end{tikzpicture}

%\caption{Block diagram of Alfvenic aurora detection algorithm.}
\label{fig:blockcv}
%\end{figure}
\end {document}

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