A Method for Correcting Signal Aberrations in Ultrasonic Indoor Positioning

Area of Science:

• Acoustics
• Signal Processing
• Indoor Positioning Systems

Background:

• Indoor positioning is crucial for many applications, driving demand for accurate tracking technologies.
• Ultrasonic systems offer good accuracy and refresh rates for indoor positioning.
• Linear chirp signals used in ultrasonic ranging can suffer from shape aberration due to acoustic diffraction.

Purpose of the Study:

• To address the limitations of classical cross-correlation techniques in ultrasonic positioning caused by signal aberration.
• To propose and evaluate an alternative range estimation technique that leverages the symmetry of aberrated cross-correlation functions.

Main Methods:

• Numerical simulations using Field II acoustic simulation software.
• Comparison of classical global peak detection with a proposed symmetry-based technique.
• Analysis under various conditions including acoustic reflections and noise levels.

Main Results:

• The proposed technique accurately estimates range even with severe cross-correlation shape aberrations.
• Effective performance is demonstrated at signal-to-noise ratio levels typical for indoor environments.
• The method accommodates reflections and noise, enabling reliable indoor positioning.

Conclusions:

• The novel symmetry-based technique overcomes classical cross-correlation errors in ultrasonic positioning.
• It allows the use of larger transducer apertures, increasing acoustic power and improving SNR.
• This enhances the feasibility of robust indoor positioning solutions.