Target Detectability Using Coded Acoustic Signal in Indoor Environments

Abstract

In this part of a work devoted to the study of relativistic continua which exhibit gyromagnetic phenomena, constitutive equations are obtained for a hyperelastic solid bq the use of the thermodynamical admissibility (Clausius-Duhem inequality), the relevant potential being the magneto-free energy written in an ud hoc invariant form after application of the author's formulation of the principle of material frame indifference. The agreement with equations derived before from a variational formulation is shown.

A Novel Ultrasonic Method for Measuring the Position and Velocity of Moving Objects in 3D Space

“…Pulse compression signals for ultrasonic methods are an ingenious solution for dealing with the practical problem in ultrasonic TOF measurement because they provide a high level of accuracy [16][17]. In general, a linear-frequency-modulated (LFM) signal can be utilized for TOF computation by using the maximum peak time in the cross-correlation function of the received signal as the reference signal.…”

Truncation-noise characteristics of finite-length M-sequence

“…To improve the signal-to-noise ratio (SNR) of the echo and the distance resolution in the measurement, pulse compression has been introduced to the pulse-echo method [5,6]. An ultrasonic wave with a sharp autocorrelation characteristic, which is the signal modulated by frequency sweep [7][8][9][10][11][12][13] or coded by pseudorandom sequences [14][15][16][17][18][19][20][21], is transmitted in pulse compression. Then, the received signal, which includes an echo, is correlated with the reference signal that corresponds to the transmitted signal.…”

“…A maximum-length sequence (M-sequence), which is one of the binary pseudo-random sequences, is used to code the transmitted signal [16][17][18][19][20][21]. When codes of the received signal and the reference signal match, a high correlation value is obtained in the cross-correlation function.…”

Measurement of ultrasonic transmission attenuation characteristics of canvas fabric

“…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]. We have also examined a noncontact measurement method for vital information, such as breathing and heartbeat, by measuring human body surface movement using airborne ultrasound [13].…”