Easily-Deployable Acoustic Local Positioning System Based on Auto-Calibrated Wireless Beacons

Abstract

Self-calibrated Acoustic Local Positioning Systems (ALPS) generally require a high consumption of hardware and software resources to obtain the user’s position at an acceptable update rate. To address this limitation, this work proposes a self-calibrated ALPS based on a software/hardware co-design approach. This working architecture allows for efficient communications, signal processing tasks, and the running of the positioning algorithm on low-cost devices. This fact also enables the real-time system operation. The proposed system is composed of a minimum of four RF-synchronized active acoustic beacons, which emit spread-spectrum modulated signals to position an unlimited number of receiver nodes. Each receiver node estimates the beacons’ position by means of an auto-calibration process and then computes its own position by means of a 3D multilateration algorithm. A set of experimental tests has been carried out where the feasibility of the proposed system is demonstrated. In these experiments, accuracies below 0.1 m are obtained in the determination of the receptor node position with respect to the set of previously-calibrated beacons.

Simulation Tool and Online Demonstrator for CDMA-Based Ultrasonic Indoor Localization Systems

“…Other works have attempted to optimize the ToA estimations through simulation and experimental tests of different encoding and modulation techniques. Examples of BPSK modulations with different digital codes can be widely found in the literature [23,36,37]. Most of these codes are designed for periodic correlation, and they present higher correlation sidelobes in case of aperiodic transmissions.…”