- Timestamp:
- 12/08/04 12:31:26 (20 years ago)
- Location:
- trunk/MagicSoft/TDAS-Extractor
- Files:
-
- 4 edited
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trunk/MagicSoft/TDAS-Extractor/Algorithms.tex
r5534 r5568 1 \section{Signal Reconstruction Algorithms }1 \section{Signal Reconstruction Algorithms \label{sec:algorithms}} 2 2 3 3 \ldots {\it In this section, the extractors are described, especially w.r.t. which free parameters are left to play, … … 176 176 The correlation of the noise contributions at times $t_i$ and $t_j$ is expressed in the noise autocorrelation matrix $\boldsymbol{B}$: 177 177 178 \begin{equation} 178 \begin{equation} 179 179 \boldsymbol{B_{ij}} = \langle b_i b_j \rangle - \langle b_i \rangle \langle b_j 180 180 \rangle \ . 181 \label{eq:autocorr} 181 182 \end{equation} 182 183 %\equiv \langle b_i b_j \rangle with $\langle b_i \rangle = 0$. … … 393 394 %%% TeX-master: "MAGIC_signal_reco" 394 395 %%% TeX-master: "MAGIC_signal_reco" 396 %%% TeX-master: "MAGIC_signal_reco" 395 397 %%% End: -
trunk/MagicSoft/TDAS-Extractor/Changelog
r5566 r5568 19 19 20 20 -*-*- END OF LINE -*-*- 21 2004/11/10: Hendrik Bartko 21 2004/12/07: Markus Gaug 22 * bibfile.bib: Modified slightly citation of NUMREC 23 * Pedestal.tex: Modified writing a bit, added references to dig.filter 24 formulas. 25 * Algorithms.tex: Added some reference labels 26 27 2004/12/06: Hendrik Bartko 22 28 * Reconstruction.tex: Added some paragraphs how we reconstruct the 23 29 average pulse shape from the recorded signal samples. Added some -
trunk/MagicSoft/TDAS-Extractor/Pedestal.tex
r5556 r5568 19 19 \vspace{1cm} 20 20 21 The Pedestal RMS can be completely described by the matrix 22 23 \begin{equation} 24 < (P_i - <P_i>) * (P_j - <P_j>) > 25 \end{equation} 26 27 where $i$ and $j$ denote the $i^{th}$ and $j^{th}$ FADC slice and 28 $P_i$ is the pedestal 29 value in slice $i$ for an event and the average $<>$ is over many events (usually 1000). 30 \par 31 32 By definition, the pedestal RMS is independent from the signal extractor. 33 Therefore, no signal extractor is needed to calculate the pedestals. 21 The background $BG$ (Pedestal) 22 can be completely described by the noise-autocorrelation matrix $\boldsymbol{B}$ 23 (eq.~\ref{eq:autocorr}), 24 where the diagonal elements give what is usually denoted as the ``Pedestal RMS''. Note that 25 in the MAGIC readout, the diagonal elements do not scale exactly with the square root of 26 the number of slices as would be expected from pure stochasitic noise. 27 28 \par 29 30 By definition, the noise autocorrelation matrix $B$ and thus the ``pedestal RMS'' 31 is independent from the signal extractor. 34 32 35 33 \subsection{Bias and Error} … … 108 106 for large signals (e.g. calibration signals). 109 107 \par 110 In the case of the optimum filter, $R$ can be obtained from the 108 In the case of the optimum filter, $R$ is in theory independent from the 109 signal amplitude $ST$ and depends only on the background $BG$, see eq.~\ref{of_noise}. 110 It can be obtained from the 111 111 fitted error of the extracted signal ($\Delta(SE)_{fitted}$), 112 which one can calculate for every event. 113 114 \vspace{1cm} 115 \ldots {\it Whether this statemebt is true should be checked by MC.} 116 \vspace{1cm} 117 118 For large signals, one would expect the bias of the extracted signal 119 to be small and negligible (i.e. $<ST> \approx <SE>$). 112 which one can calculate for every event or by applying the extractor to a fixed window 113 of pure background events (``pedestal events''). 114 120 115 \par 121 116 122 117 In order to get the missing information, we did the following investigations: 123 118 \begin{enumerate} 119 \item Determine $R$ by applying the signal extractor to a fixed window 120 of pedestal events. The background fluctuations can be simulated with different 121 levels of night sky background and the continuous light, but no signal size 122 dependency can be retrieved with the method. 124 123 \item Determine bias $B$ and resolution $R$ from MC events with and without added noise. 125 124 Assuming that $R$ and $B$ are negligible for the events without noise, one can 126 125 get a dependency of both values from the size of the signal. 127 126 \item Determine $R$ from the fitted error of $SE$, which is possible for the 128 fit and the digital filter. In prinicple, all dependencies can be retrieved with this 129 method. 130 \item Determine $R$ for low signals by applying the signal extractor to a fixed window 131 of pedestal events. The background fluctuations can be simulated with different 132 levels of night sky background and the continuous light, but no signal size 133 dependency can be retrieved with the method. Its results are only valid for small 134 signals. 127 fit and the digital filter (eq.~\ref{of_noise}). 128 In prinicple, all dependencies can be retrieved with this method. 135 129 \end{enumerate} 136 137 \par138 130 139 131 \subsubsection{Determine error $R$ by applying the signal extractor to a fixed window 140 132 of pedestal events} 141 133 142 By applying the signal extractor to pedestal events we want to143 determine these parameters. There are the following possibilities:144 145 \begin{enumerate} 146 \item Applying the signal extractor allowing for a possible sliding window147 to get information about the bias $B$ (valid for low signals). 148 \item Applying the signal extractor to a fixed window, to get something like 149 $R$. In the case of the digital filter and the spline, this has to be done 150 by randomizing the time slice indices. 151 \end{enumerate} 152 153 \vspace{1cm} 154 \ldots {\it This assumptions still have to proven, best mathematically!!! Wolfgang, Thomas???} 155 \vspace{1cm} 134 By applying the signal extractor to a fixed window of pedestal events, we 135 determined the parameter $R$ for the case of no signal ($ST = 0$). In the case of 136 all extractors using a fixed window from the beginning (extractors nr. \#1 to \#22 137 in section~\ref{sec:algorithms}), the results were exactly the same as calculating 138 the mean and the RMS of a same (fixed) number of FADC slices (the conventional ``Pedestal 139 Calculation''). 140 141 \par 142 In the case of the amplitude extracting spline (extractor nr. \#27), we took the 143 spline value at a random place within the digitizing binning resolution (0.02 FADC slices) of 144 one central FADC slice. 145 In the case of the digital filter (extractor nr. \#28), the time shift was 146 randomized for each event within one central FADC slice. 147 156 148 \par 157 149 … … 331 323 %%% TeX-master: "MAGIC_signal_reco." 332 324 %%% TeX-master: "MAGIC_signal_reco" 325 %%% TeX-master: "Pedestal" 333 326 %%% End: -
trunk/MagicSoft/TDAS-Extractor/bibfile.bib
r5266 r5568 16 16 } 17 17 18 @Book{NumRec, 19 author = "W.H.Press and S.A.Teukolsky and W.T.Vetterling and B.P.Flannery", 20 title = "Numerical Recipes in C++, 2nd edition", 18 @Book{NUMREC, 19 author = "W.H.Press and S.A.Teukolsky and W.T.Vetterling and B.P.Flannery", 20 title = "Numerical Recipes in C++", 21 edition = "Second", 21 22 publisher = "Cambridge University Press", 22 23 year = "2002"
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