Improving the accuracy of ultrasound-based localisation systems

We present an improvement to ultrasound-based indoor location systems like Cricket (Priyantha et al. The Cricket location-support system, 2000). By encoding and modulating the ultrasound pulses, we are able to achieve greater accuracy in distance measurements. Besides improving the distance measurements, we improve the position update rate by synchronising the active beacons. We also propose a method that could further improve the update rate by superimposing encoded ultrasound pulses. Further, an experimental evaluation of our improvements is presented. [PUBLICATION ABSTRACT]