sgrpdlay.tex

时频分析的工具包

% This is part of the TFTB Reference Manual.
% Copyright (C) 1996 CNRS (France) and Rice University (US).
% See the file refguide.tex for copying conditions.


\markright{sgrpdlay}
\hspace*{-1.6cm}{\Large \bf sgrpdlay}

\vspace*{-.4cm}
\hspace*{-1.6cm}\rule[0in]{16.5cm}{.02cm}
\vspace*{.2cm}

{\bf \large \fontfamily{cmss}\selectfont Purpose}\\
\hspace*{1.5cm}
\begin{minipage}[t]{13.5cm}
Group delay estimation of a signal.
\end{minipage}
\vspace*{.5cm}

{\bf \large \fontfamily{cmss}\selectfont Synopsis}\\
\hspace*{1.5cm}
\begin{minipage}[t]{13.5cm}
\begin{verbatim}
[gd,fnorm] = sgrpdlay(x)
[gd,fnorm] = sgrpdlay(x,fnorm)
\end{verbatim}
\end{minipage}
\vspace*{.5cm}

{\bf \large \fontfamily{cmss}\selectfont Description}\\
\hspace*{1.5cm}
\begin{minipage}[t]{13.5cm}
        {\ty sgrpdlay} estimates the group delay of a signal {\ty x} at the
        normalized frequency(ies) {\ty fnorm}.\\

\hspace*{-.5cm}\begin{tabular*}{14cm}{p{1.5cm} p{7.5cm} c}
Name & Description & Default value\\
\hline
        {\ty x}     & signal in the time-domain ({\ty N=length(x)})\\
        {\ty fnorm} & normalized frequency & {\ty linspace(-.5,.5,N)}\\ 
\hline  {\ty gd}    & output vector containing the group delay
	samples. When GD equals zero, it means that the estimation of the
	group delay for this frequency was outside the interval {\ty [1 xrow]},
	and therefore meaningless.\\ 

\hline
\end{tabular*}

\end{minipage}
\vspace*{1cm}

{\bf \large \fontfamily{cmss}\selectfont Example}\\
\hspace*{1.5cm}
\begin{minipage}[t]{13.5cm}
Let us compare the estimated group-delay and instantaneous frequency of a
linear chirp signal : 
\begin{verbatim}
         N=128; x=fmlin(N,0.1,0.4);
         fnorm=0.1:0.04:0.38; gd=sgrpdlay(x,fnorm); 
         t=2:N-1; instf=instfreq(x,t);
         plot(t,instf,gd,fnorm); axis([1 N 0 0.5]); 
\end{verbatim}
The two curves are almost superposed, which is normal for a large
time-bandwidth product signal.
\end{minipage}
\vspace*{.5cm}

{\bf \large \fontfamily{cmss}\selectfont See Also}\\
\hspace*{1.5cm}
\begin{minipage}[t]{13.5cm}
\begin{verbatim}
instfreq.
\end{verbatim}
\end{minipage}