Office of Technology Transfer – University of Michigan

EchoTag: Accurate Infrastructure-Free Indoor Location Sensing with Smartphones

Technology #6506

Questions about this technology? Ask a Technology Manager

Download Printable PDF

Image Gallery
Location sensing based on sound
Kang Geun Shin
Managed By
Drew Bennett
Associate Director - Software Licensing 734-615-4004
Patent Protection
US Patent Pending

This technology allows mobile smartphones to determine if the phone is placed in pre-programmed locations in a room and activate mobile applications. Thus, it would free the user from having to manually adjust settings frequently. For example, the technology would enable the phone to automatically switch to silent mode when placed next to the user’s bed. About $ 1.2 billion smartphones are expected to be sold in 2014. Thus, this technology could have a large user base.

Reflection of Sound Used to Determine Location

The technology uses low volume sounds emitted from the mobile phone in pulses. The phone then senses the reflections of these sounds to determine the location. In addition, the application also uses data from the phone’s gyroscopes, accelerometers and WiFi receivers to determine the appropriate time to check for the location. The application needs to be trained to identify specific locations. Unlike other location sensing technologies, this technology does not require the installation of any special hardware in the room. Moreover, the technology can be implemented in multiple mobile operating systems.


  • Activate specific apps when placed in a pre-set location
  • Provide a log of users’ activities


  • No other infrastructure needed
  • Little disturbance to user
  • Not power intensive
  • Implemented in multiple operating systems