An ultrasonic ranging system for structural vibration measurements

Robust High-Accuracy Ultrasonic Range Measurement System

“…The single-frequency continuous wave phase shift method [12] is the basic technique used to estimate range using ultrasonic signal with high accuracy. However the maximum range that can be estimated using this technique alone is limited to one wavelength of the carrier frequency which means that at 40 KHz the maximum range is limited to 8.575 mm assuming a sound velocity of 343 m/s.…”

“…Many ultrasonic range measurement methods have been proposed in the literature [12][13][14][15][16][17][18][19]. Time of Flight (TOF) and phase shift methods are used in most ultrasonic range measurement systems.…”

High-Accuracy Reference-Free Ultrasonic Location Estimation

“…Their accuracy is primarily due to the low velocity of ultrasonic wave propagation in air, allowing high accuracy Time of Flight (ToF) measurement. Typical ultrasonic location systems exploit the difference in the Times of Arrival (ToA) of a narrowband ultrasonic signal and a reference Radio Frequency (RF) pulse emitted synchronously with the ultrasonic signal, to estimate the distance between the transmitter and the receiver based on the known propagation speed of sound in air [13], [14]. Unfortunately, the inclusion of a RF sub-system to provide a timing reference adds significant cost, size, power consumption and complexity to such systems [15].…”

Noncontact Monitoring of Respiration Based on an Ultrasonic Phase-Shift Reconstruction Method

“…In some applications, it is not possible to attach a measur ing device directly onto the vibration structure. So the pulse-echo methods [6][7][8][9] for measuring the time elapsed while the ultrasonic pulse travels from trans mitter to receiver and multiplying the half time by the sound speed to get the distance between transducer and object were developed. Nevertheless, this method can only be used to measure a slowly moving object.…”

“…Nevertheless, this method can only be used to measure a slowly moving object. To overcome the drawback, Figueroa and Barbieri pre sented an ultrasonic ranging system based on the phase shift method for structural vibration measurement [7][8][9][10]. However, the measurement resolution of this method varies with the range of the displacements be ing measured.…”