Dynamic Adjustment of Weighted GCC-PHAT for Position Estimation in an Ultrasonic Local Positioning System.

Area of Science:

• Acoustics
• Signal Processing
• Indoor Localization Technologies

Background:

• Ultrasonic local positioning systems (ULPS) offer a balance of precision, development ease, and cost for indoor localization.
• Accurate detection of ultrasonic beacon emissions is crucial for ULPS performance, especially in low signal-to-noise ratio (SNR) or multipath environments.

Purpose of the Study:

• To propose and evaluate an enhanced method for accurate ULPS implementation using ultrasonic beacons.
• To improve the robustness and precision of ULPS in challenging indoor acoustic conditions.

Main Methods:

• Utilized generalized cross-correlation with a PHAT filter and a weighting factor (GCC-PHAT-β) for time-of-arrival measurement.
• Implemented mixed-medium multiple-access techniques (CDMA and TDMA) for beacon emission multiplexing.
• Employed hyperbolic multilateration based on time differences of arrival (TDoA) for receiver positioning, eliminating synchronization needs.

Main Results:

• Dynamic adaptation of the PHAT filter weighting factor significantly reduced positioning errors from 20 cm to 2 cm in 80% of measurements.
• The proposed algorithms demonstrated improved ULPS performance in low SNR (< 0 dB) conditions.
• Effectiveness was proven in environments with significant multipath interference, enhancing encoded ultrasonic emission detection.

Conclusions:

• The proposed GCC-PHAT-β method with dynamic weighting factor adaptation and mixed-medium access techniques enhances ULPS accuracy and reliability.
• This approach offers a robust solution for indoor localization challenges, including low SNR and multipath effects.
• The system provides precise positioning without requiring receiver synchronization, simplifying practical implementation.