4410-4412: add waveform for ram mod e.g.

4410-4412.tex

@@ -444,6 +444,7 @@ def run(self):
 
 \newpage
 \subsection{DDS RAM Modulation (AD9910 Only)}
+This examples demonstrates that the RF signal can be modulated by amplitude using the RAM modulation feature of AD9910.
 Set field \texttt{dds} as an Urukul channel, \texttt{cpld} as the corresponding Urukul CPLD.
 
 \begin{minted}{python}
@@ -479,6 +480,24 @@ def profile0_set(self):
     self.cpld.io_update.pulse_mu(8)
 \end{minted}
 
+The generated RF output of the above example consists of the following features in sequence:
+\begin{enumerate}
+    \item A 10 MHz RF pulse for 2 microseconds.
+    \item No signal for 1 microseconds.
+    \item A 10 MHz RF pulse for 1 microseconds.
+    \item No signal for 3 microseconds.
+    \item Go back to item 1.
+\end{enumerate}
+The expected waveform is plotted on the following figure.
+
+\begin{figure}[h]
+    \centering
+    \includegraphics[width=\textwidth]{ad9910_amp_mod.png}
+    \caption{RF output from DDS RAM modulation example}
+\end{figure}
+
+\newpage
+
 \section{Ordering Information}
 To order, please visit \url{https://m-labs.hk} and select the 4410 Urukul in the ARTIQ Sinara crate configuration tool.
 The default chip is AD9910 (4410 Urukul), which supports more features.