Hardware Reference
In-Depth Information
Preparing a GPS beacon on the Pi
To get the GPS data into a remote Google Earth session for live tracking, we must
first massage the data into the
Keyhole Markup Language
(
KML
) format that
Google Earth expects and then serve the data over an HTTP link so that Google Earth
can request new GPS data at regular intervals.
First, we need to download a Python script called
gegpsd.py
written by Stephen
Youndt with the following command:
pi@raspberrypi ~ $ wget http://www.intestinate.com/gegpsd.py
This script will continuously fetch data from
gpsd
and write it, in the KML format,
to
/tmp/nmea.kml
. We'll also need an HTTP server to serve this file to Google Earth.
Python comes with a simple HTTP server that we can use for this purpose. Start the
Python script and HTTP server using the following command:
pi@raspberrypi ~ $ python ~/gegpsd.py & cd /tmp && python -m
SimpleHTTPServer
The KML data should now be generated and available from
http://[IP
address]:8000/nmea.kml
where
[IP address]
is the address of your Raspberry Pi.
Let's move on to Google Earth.
Setting up Google Earth
The setup procedure for Google Earth is very similar across all platforms:
1.
download Google Earth for your platform.
2.
Install and start Google Earth.
3.
From the
Add
drop-down menu, select
Network Link
.
4.
Put a name for your GPS link in the
Name
field and add the
http://[IP
address]:8000/nmea.kml
KML data link to the
Link
field.
5.
Go to the
Refresh
tab and change the
Time-Based Refresh
to
Periodically
in
the drop-down menu.
6.
(Optional) Tick the
Fly to View on Refresh
checkbox to have the view
automatically centered on your GPS as it moves.
7.
Now click on the
OK
button and you should see your GPS link as an entry
under
My Places
in the sidebar on the left-hand side. Double-click on it to
zoom in on your GPS location.
