Low Cost Altimeter Project

These pages document a short research project undertaken at the Geospatial Research Centre in order to investigate low cost solutions for altimetry. The aim of this research is to identify possible sub-$1000 devices and see if they:

  • Are capable of determining the height of a unmanned aerial vehicle (UAV) above ground to about 10% accuracy
  • Will function over altitudes from 200m to 1000m - functioning under 200m would be a bonus
  • Have a small form factor and low power usage

After some initial research two directions were chosen in collaboration with our partners. The first of these, 'Bistatic GPS', is based on using two GPS receivers, one of which views signals reflected off the ground. The basis of this approach is that the reflected signals travel further, and the higher the aircraft is above the ground the greater the extra distance the signal must traverse. The second approach, 'Optical Flow Altimetry', works by knowing the aircraft's ground speed (from GPS, say), and watching the ground with a simple camera (based on an optical mouse chip). The lower the aircraft is flying, the faster the ground will appear to go by at any given speed.

Bistatic GPS

Optical Flow Altimetry

Hardware schematics for this project are available through the Trac repository, as is the source code for the firmware.

Terms of Release

  • The software is released under the Apache 2.0 License
  • The hardware designs are made freely available
  • The GRC assumes no liability of ANY kind (direct or consequential), for damages or other problems which may result from the use of the device, software, documentation, or any thing else provided by this project.

Attachments