Estimation of Receiving Waveform of Ultrasonic Aerial Back Sonar Calculated by Finite Difference Time Domain Method

Abstract

In order to develop a high-performance aerial back sonar for a car, we predicted the waveforms of the received pulse using the finite difference time domain (FDTD) method. The echo pulses reflected from the target were calculated as a function of the target's height in air at an inhomogeneous temperature. The maximum amplitudes of the pulse train changed with the target's height. The amplitude and propagation time of the reflected pulse markedly differed with shape of targets at a constant temperature. The result shows that an aerial sensor should be able to detect a square target at an inhomogeneous temperature such as that in summer. However, it is very difficult to detect a slanted target.

High-intensity aerial ultrasonic source with sharp directivity containing a compact circular vibrating plate

“…In recent years, there has been much research on the noncontact use of aerial ultrasound, such as the use of strong ultrasound using ultrasonic sensors. [1][2][3][4][5][6][7][8][9][10][11][12] However, because of the small size of ultrasonic sensors, the sound pressure of sound waves that can be emitted by a single sensor is low. Therefore, in order to emit sound waves with high sound pressure, ultrasonic sensors are arrayed in large numbers (50-300) and used as a focusing sound source.…”

Measurement of ultrasonic transmission attenuation characteristics of canvas fabric

“…Acoustic sensing in air has potential applications for obtaining various types of information about the surrounding object such as its position, shape, material and movement [1][2][3][4][5][6][7][8][9][10]. We reported results of the position detection of small objects with a size comparable to the signal wavelength, using an M-sequence-modulated signal [11,12].…”

Two-Dimensional Simulation of Nonlinear Acoustic Wave Propagation Using Constrained Interpolation Profile Method

“…Development of accurate numerical schemes is an important technical issue. [1][2][3][4][5][6] At present, the finite difference time domain (FDTD) method is probably the most popular numerical method for the solution of linear wave propagation in acoustics. In the FDTD method, the central finite differences for the space and time derivatives are used to approximate the continuous derivatives of the governing equations.…”