20.tex

\begin{itemize}
\item{Class notes: 2-11-16}
\subsection*{Matlab demo}

\item{
zp2tf: zero pole to transfer function, gives us our A and B coefficients.
}

\item{
Frequency vector returned by freqs is useful for plots. 
}

\item{
Phase plot: how to convert phase to time delay? Find the slope of the phase (phase delay):
\begin{align*}
-\frac{\theta(\omega)}{\omega}
\end{align*} 
}

\item{
Plotting group delay: plot(w(1:end-1), -diff(unwrap(angle(H)))/w)
}

\item{
We have 1400 samples of delay at the corner frequency
}

\item{
There should be a filter designed to be similar to the butterworth filter, so you can
call it "I can't believe it's not butter".
}

\item{
Convert to radians: freq * 2 * pi
}

\subsection*{Julius}
\item{
FDA tool: Filter Desgin and Analysis
}

\item{
Tool only available in MATLAB, not Octave
}

\item{
Able to generate Matlab code.
}

\item{
Maximally flat: for group delay it's called a Bessel Filter. For butterworth it's something else... (phase?)
}

\subsection*{Part 2: more FDA}
\item{
Alternation Thereom
}

\item{
Pi rotate a filter: $-1^{n}$: Negate every other coefficient.
}

\item{
Hipass IR: sample sync function with every other sample negated
}

\item{

}

\end{itemize}