diff --git a/src/Glossary.tex b/src/Glossary.tex
index 826b248..7535944 100644
--- a/src/Glossary.tex
+++ b/src/Glossary.tex
@@ -432,3 +432,6 @@
 % sidereal
 % slew
 % sky chart
+% PPS (gps)
+% gpsd
+% List of Software ?
diff --git a/src/Ground_Stations.tex b/src/Ground_Stations.tex
index 2e43ac8..e15c582 100644
--- a/src/Ground_Stations.tex
+++ b/src/Ground_Stations.tex
@@ -73,7 +73,7 @@ can be seen in Figure
 	\begin{center}
 		\centering
 		\includegraphics[keepaspectratio=true,height=1.00\textheight,width=1.00\textwidth,angle=0]{video-enclosure-mount-tripod.png}
-		\caption{SatNOGS-Optical ground station prototype.}
+		\caption{SatNOGS Optical ground station prototype.}
 		\label{fig:video-enclosure-mount-tripod}
 		\index{telescope}\index{tripod}\index{mount}\index{enclosure}
 	\end{center}
diff --git a/src/Software.tex b/src/Software.tex
index 76c99f7..50b92ed 100644
--- a/src/Software.tex
+++ b/src/Software.tex
@@ -328,7 +328,7 @@ Software that can be used with telescope tracking mounts:
         \item [INDI] --- Main client/server used by other applications.
         \item [KStars] --- Sky charts, INDI control.
 	\item [Ekos] --- Application used within KStars for remote control
-         of telescopes and related hardware via \gls{INDI}.
+         of \glspl{telescope} and related hardware via \gls{INDI}.
         \item [Stellarium] --- Sky charts, has \gls{INDI} plugin.
 	\item [Other INDI] --- Many more applications work with \gls{INDI}.
 	\item [INDIGO] --- Positions itself as a next-generation INDI (?).
@@ -386,10 +386,31 @@ hardware described in section \ref{sec:hardware-mounts}, page \pageref{sec:hardw
 
 For the purposes here, described below will be using KStars with a
 Sky-Watcher tracking mount with INDI and Ekos.
-It will be used in sidereal tracking mode, where the stars will appear as
+See figure \ref{fig:video-enclosure-mount-tripod}, page \pageref{fig:video-enclosure-mount-tripod}
+for a photo of the setup used with KStars below.
+
+The telescope mount will be used in sidereal tracking mode,
+where the stars will appear as
 ``points'', and the \glspl{satellite} will appear as trails.
+The mount is not used in a satellite tracking mode.
+Sidereal is the ``standard'' tracking mode of \glspl{telescope}.
 \index{Sky-Watcher}\index{INDI}\index{Ekos}
 
+KStars is the ``main'' application, but it depends on other key parts.
+\gls{INDI} is the protocol that KStars uses for telescope control.
+\gls{INDI} itself is a collection of applications.
+While KStars has the main sky chart and Ekos is launched within it,
+the actual mount control is done with the Ekos application.
+While it may sound complex, all of this is set up pretty easily in
+\gls{Debian}.
+
+\begin{minted}{sh}
+# Quick and dirty from memory, something like:
+sudo apt update
+sudo apt install kstars indi-bin indi-eqmod indi-gpsd
+\end{minted}
+
+
 \begin{sidewaysfigure}[p!]
         \begin{center}
                 \includegraphics[keepaspectratio=true,height=1.00\textheight,width=1.00\textwidth,angle=0]{kstars-skychart.png}
@@ -417,3 +438,94 @@ It will be used in sidereal tracking mode, where the stars will appear as
         \end{center}
 \end{sidewaysfigure}
 
+
+\section{GNSS}
+\label{sec:software-overview}
+\index{GNSS}\index{GPS}\index{Galileo}\index{GLONASS}\index{Beidou}
+\index{gpsd}
+
+\gls{GNSS} is used for time synchornization and for (somewhat)
+accurately determining the location of the observation.
+
+\gls{GNSS} collectively includes the USA \gls{GPS}, Europe's Galileo,
+Russia's GLONASS, and China's Beidou, as well as other
+regional systems.
+\index{GPS}\index{Galileo}\index{GLONASS}\index{Beidou}
+
+A basic, widely available \gls{COTS} USB \gls{GNSS} device
+with a basic (or no!) \gls{antenna} plugged into the embedded
+computer can get time and location accurate enough for the
+purposes here. See various U-Blox devices, for example.
+\index{COTS}\index{USB}
+
+In \gls{Debian} \gls{GNSS} service with a USB device can be provided
+by the \texttt{gpsd} application.
+
+\begin{minted}{sh}
+sudo apt install gpsd gpsd-tools
+\end{minted}
+
+Edit the configuration file, \texttt{/etc/default/gpsd} like:
+
+\begin{minted}{sh}
+DEVICES="/dev/ttyACM0"
+GPSD_OPTIONS="-Gn"
+USBAUTO="false"
+\end{minted}
+
+This will start a \texttt{gpsd} daemon listening on all interfaces,
+so it can be used by other computers on the network (such as if
+acquire and process are on different machines). Using the
+device \texttt{/dev/ttyACM0} can be problematic if there are multiple
+\texttt{/dev/ttyACM*} devices. Perhaps something like this could be
+used in that case:
+
+\begin{minted}{sh}
+DEVICES="/dev/serial/by-id/usb-u-blox_AG_-_www.u-blox.com_u-blox_GNSS_receiver-if00"
+\end{minted}
+
+Even with \texttt{gpsd} configuration listening on all IPs,
+don't think \texttt{systemd} won't do what it likes. So
+you may have to do:
+
+\begin{minted}{sh}
+systemctl edit --full gpsd.socket
+\end{minted}
+
+And create a configuration like this (I have IPv6 disabled, in this case):
+
+\begin{minted}{sh}
+[Unit]
+Description=GPS (Global Positioning System) Daemon Sockets
+
+[Socket]
+ListenStream=/run/gpsd.sock
+# ListenStream=[::]:2947
+ListenStream=0.0.0.0:2947
+SocketMode=0600
+BindIPv6Only=no
+
+[Install]
+WantedBy=sockets.target
+\end{minted}
+
+(Re)start:
+
+\begin{minted}{sh}
+sudo systemctl restart gpsd.service gpsd.socket
+\end{minted}
+
+Test all is good:
+
+\begin{minted}{sh}
+gpsmon -n
+# or
+cgps -u m
+\end{minted}
+
+Enable to start on boot:
+
+\begin{minted}{sh}
+sudo systemctl enable gpsd.service gpsd.socket
+\end{minted}
+