For the car I have a “car PC” which is a miniature low-power PC motherboard housed in a tough metal case with a power supply designed specifically for car use. Externally is has a Wifi dongle for internet access via a 3G access point, a GPS receiver, and a 7″ touchscreen monitor. Internally it has an accelerometer.
For this I’ve written a simple program designed for touchscreen use, providing functions such as mp3 player, clock and a GPS/accelerometer screen. I’ve now extended that to include special functions for use when chasing a high-altitude balloon. Here’s the main menu screen:
The GPS/accelerometer screen shows the data from those devices:
More interestingly, there’s a screen for showing where the balloon is. The compass shows the direction and distance (using a log scale) to the balloon, plus a second smaller compass to show the speed and direction of the balloon. The two together give an idea where to drive to so you meet the payload as it lands.
Finally there’s a split screen which has the HAB information at the top, above the dl-fldigi modem program which receives the payload telemetry. This allows the operator to adjust the tuning of the modem at the same time as viewing the payload position etc.
Telemetry from the balloon is uploaded to a web server, either via the chase car or by fixed stations at the homes of other enthusiasts. The server runs a map which anyone can access using a web browser, so I added a browser to the program:
Finally, I added a special browser for Google Maps. This browser reads the car position from the GPS, and the payload position from the incoming telemetry, and can then plot a route between the two: