In this study, we propose a method to estimate the position and velocity of a target using a 40-kHz airborne ultrasound transducer array. Unlike Doppler-based techniques that analyze frequency shifts, our approach leverages fine phase differences between consecutive echo signals. In addition to high-resolution velocity estimation, it enables spatial localization in two dimensions, allowing precise tracking of both motion and position. The system is composed of a 12-channel 1-D transmitting array and a 2-channel 1-D receiving array. Ultrasonic pulses are transmitted and received in real time through an ADC precisely synchronized with the transmission cycle. By applying phase control to the transducer array, beam steering within ±20° is achieved, enabling directional sensitivity. A quantitative velocity estimation algorithm based on phase delay, combined with compensation and filtering techniques, further enhances the system’s sensitivity and robustness. The system can resolve velocities as low as 10 μm/s. The system accurately detects human respiration from 1 m without any physical contact. These results demonstrate its potential for remote monitoring of subtle biological movements in human-centered applications. Work supported by the Technology Innovation Program (RS-2024-00445152) funded By Ministry of Trade, Industry and Energy (MOTIE, Korea).
Kim et al. (Wed,) studied this question.