The Cricket location-support system
MobiCom '00 Proceedings of the 6th annual international conference on Mobile computing and networking
Multiuser Detection
A Novel Broadband Ultrasonic Location System
UbiComp '02 Proceedings of the 4th international conference on Ubiquitous Computing
An Overview of Wireless Indoor Geolocation Techniques and Systems
NETWORKING '00 Proceedings of the IFIP-TC6/European Commission International Workshop on Mobile and Wireless Communication Networks
A High Performance Privacy-Oriented Location System
PERCOM '03 Proceedings of the First IEEE International Conference on Pervasive Computing and Communications
Timing-sync protocol for sensor networks
Proceedings of the 1st international conference on Embedded networked sensor systems
The flooding time synchronization protocol
SenSys '04 Proceedings of the 2nd international conference on Embedded networked sensor systems
Fine-grained network time synchronization using reference broadcasts
OSDI '02 Proceedings of the 5th symposium on Operating systems design and implementationCopyright restrictions prevent ACM from being able to make the PDFs for this conference available for downloading
WALRUS: wireless acoustic location with room-level resolution using ultrasound
Proceedings of the 3rd international conference on Mobile systems, applications, and services
eWatch: A Wearable Sensor and Notification Platform
BSN '06 Proceedings of the International Workshop on Wearable and Implantable Body Sensor Networks
Accessible Ultrasonic Positioning
IEEE Pervasive Computing
A BeepBeep ranging system on mobile phones
Proceedings of the 5th international conference on Embedded networked sensor systems
A survey on localization for mobile wireless sensor networks
MELT'09 Proceedings of the 2nd international conference on Mobile entity localization and tracking in GPS-less environments
Indoor localization without infrastructure using the acoustic background spectrum
MobiSys '11 Proceedings of the 9th international conference on Mobile systems, applications, and services
Detecting driver phone use leveraging car speakers
MobiCom '11 Proceedings of the 17th annual international conference on Mobile computing and networking
MoteTrack: a robust, decentralized approach to RF-Based location tracking
LoCA'05 Proceedings of the First international conference on Location- and Context-Awareness
Indoor pseudo-ranging of mobile devices using ultrasonic chirps
Proceedings of the 10th ACM Conference on Embedded Network Sensor Systems
Spartacus: spatially-aware interaction for mobile devices through energy-efficient audio sensing
Proceeding of the 11th annual international conference on Mobile systems, applications, and services
IAMHear: a tabletop interface with smart mobile devices using acoustic location
CHI '13 Extended Abstracts on Human Factors in Computing Systems
Proceedings of the 11th ACM Conference on Embedded Networked Sensor Systems
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In this paper, we present an indoor ultrasonic location tracking system that can utilize off-the-shelf audio speakers (potentially already in place) to provide fine-grained indoor position data to modern mobile devices like smartphones and tablets. We design and evaluate a communication primitive based on rate-adaptive wide-band linear frequency modulated chirp pulses that utilizes the audio bandwidth just above the human hearing frequency range where mobile devices are still sensitive. Typically transmitting data, even outside of this range, introduces broadband human audible noises (clicks) due to the non-ideal impulse response of speakers. Unlike existing audio modulation schemes, our scheme is optimized based on psychoacoustic properties. For example, all tones exhibit slowly changing power-levels and gradual frequency changes so as to minimize human perceivable artifacts. Chirps also bring the benefit of Pulse Compression, which greatly improves ranging resolution and makes them resilient to both Doppler shifts as well as multi-path propagation that typically plague indoor environments. The scheme also supports the decoding of multiple unique identifier packets being transmitted simultaneously. By applying a Time-Difference-of-Arrival (TDOA) pseudo-ranging technique the mobile devices can localize themselves without tight out-of-band synchronization with the broadcasting infrastructure. This design is not only scalable with respect to the number of transmitters and tracked devices, but also improves user privacy since the mobile devices compute their positions locally. We show through user studies and experimentation on smartphones that we are able to provide sub-meter (95% cm) accurate indoor positioning in a manner that is imperceptible to humans.