Ultrasonic time synchronization and ranging on smartphones

—In this paper, we present the design and evaluation of a platform that can be used for time synchronization and indoor positioning of mobile devices. The platform uses the Time-Difference-Of-Arrival (TDOA) of multiple ultrasonic chirps broadcast from a network of beacons placed throughout the environment to find an initial location as well as synchronize a receiver’s clock with the infrastructure. These chirps encode identification data and ranging information that can be used to compute the receiver’s location. Once the clocks have been synchronized, the system can continue performing localization directly using Time-of-Flight (TOF) ranging as opposed to TDOA. This provides similar position accuracy with fewer beacons (for tens of minutes) until the mobile device clock dirfts enough that a TDOA signal is once again required. Our hardware platform uses RF-based time synchronization to distribute clock synchronization from a subset of infrastructure beacons connected to a GPS s...

• Type: Journal
• Year: 2015
• Where: RTAS
• Authors: Patrick Lazik, Niranjini Rajagopal, Bruno Sinopoli, Anthony Rowe
• Keywords: Embedded Systems, RTAS 2015