Acoustic Self-Calibrating System for Indoor Smart Phone Tracking

Abstract

This paper presents an acoustic indoor localization system for commercial smart phones that emit high pitched acoustic signals beyond the audible range. The acoustic signals with an identifier code modulated on the signal are detected by self-built receivers which are placed at the ceiling or on walls in a room. The receivers are connected in a Wi-Fi network, such that they synchronize their clocks and exchange the time differences of arrival (TDoA) of the received chirps. The location of the smart phone is calculated by TDoA multilateration. The precise time measuring of sound enables high precision localization in indoor areas. Our approach enables applications that require high accuracy, such as finding products in a supermarket or guiding blind people through complicated buildings. We have evaluated our system in real-world experiments using different algorithms for calibrationfree localization and different types of sound signals. The adaptive GOGO-CFAR threshold enables a detection of 48% of the chirp pulses even at a distance of 30 m. In addition, we have compared the trajectory of a pedestrian carrying a smart phone to reference positions of an optic system. Consequently, the localization error is observed to be less than 30 cm.

BlueDetect: An iBeacon-Enabled Scheme for Accurate and Energy-Efficient Indoor-Outdoor Detection and Seamless Location-Based Service

“…When it comes to indoor environments, the past decade has witnessed flourishing research on indoor positioning systems (IPSs) [ 4 , 5 ]. A variety of sensing technologies have been proposed, including radio frequency identification (RFID) [ 6 , 7 ], WiFi [ 8 , 9 , 10 , 11 , 12 ], acoustic signals [ 13 , 14 , 15 ], geomagnetic fields [ 16 , 17 ], pedestrian dead reckoning (PDR) [ 18 ] and Bluetooth [ 19 ], which utilize on-board sensors, such as the accelerometer, gyroscope, microphone, WiFi module and Bluetooth module. WiFi is the primary alternative to GPS to perform indoor localization, since existing WiFi network infrastructures have been widely available in the majority of commercial and residential buildings, and more importantly, nearly every commercial mobile device is WiFi enabled.…”

Acoustic Wake-Up Receivers for Home Automation Control Applications

“…The efficiency of the MEMS microphone is measured [20] to see in which direction and at what angles would be suitable for placing the microphone. In this measurement, 10 receivers are used.…”

Acoustic Indoor Localization Augmentation by Self-Calibration and Machine Learning

“…The RF-Systems use the propagation of radio waves. Another possibility is to use the propagation of sound for localization [7,8]. Indoor localization systems work with indoor satellites (anchor nodes), which have to be installed inside the indoor environment.…”