\section{How to read out noise}

\subsection{Noise readout without glass fiber}

First configure the chamber with config cf\_p\_nozs\_tb30\_trk\_autotrg (2008.2, command 503 here in MS).
Afterwards log in on the dcs board and execute the following commands

\begin{compactenum}
\item \inputcmd{ttcrx\_regs s} -- enables software trigger
\item \inputcmd{pretrigger 1} -- send pretrigger
\item repeat \inputcmd{pretrigger 1} several times to get a little bit statistic
\end{compactenum}

Then you can read out the results via \inputcmd{adcrms $>$ /tmp/noise} and copy the
file \filepath{/tmp/noise} to a directory on a normal computer where your plot script 
is located. In MS you would use \inputcmd{scp /tmp/noise trd@trd01:eva/fast\_noise/noise\_filename}.

Last step is to log out from the DCS board and start your plot script on the normal computer. In MS the 
script sits in \filepath{trd01:/home/trd/eva/fast\_noise} and is executed with the command 
\inputcmd{root 'rmsplot.C("noise\_filename")'}.

\subsection{Noise readout via GTU}

To read out noise via GTU configure the chamber(s) like above and then a run in DATE. To send triggers to the chamber(s) execute in a shell on trd01:

\begin{compactenum}
\item \inputcmd{ttccmd 3} -- start sending trigger (aprox. 180 per second)
\item wait a few seconds (2 or 3)
\item \inputcmd{ttccmd 7} -- stop sending trigger
\end{compactenum}

or use the Perl/Tk GUI at the trd02 desktop (click on the noise button there).\\

Then wait (a few seconds) until DATE has written the buffer to the disk and stop the run. Keep the run number in mind!

Logon to daq01, there execute the following commands\\

\begin{compactenum}
\item \inputcmd{. ~/change\_to\_v4-10} -- the dot at the beginning is important to set the enviroment var!
\item \inputcmd{cd /data/01/eva/noise}
\item \inputcmd{aliroot PHdigits.cxx} -- load the code which reads the noise data later
\item \inputcmd{PHdigits(<runNo>, <partNo>)} -- AliRoot inside: e.g. PHdigits(447,000) for the daq01\_run447.000.raw file
\item \inputcmd{monitorNoise(<Layer>)} -- AliRoot inside: e.g. monitorNoise(2)
\end{compactenum}
