Ke-Yu Lee Chih-Feng Huang Sin-San Huang Ke-Nung Huang Ming-Shing Young A High-Resolution Ultrasonic Distance Measurement System Using Vernier Caliper Phase Meter. 2924-2931 2012 61 IEEE Trans. Instrum. Meas. 11 https://doi.org/10.1109/TIM.2012.2203871 db/journals/tim/tim61.html#LeeHHHY12