Ultrasonic inspection method for billet using time-of-flight deviation of bottom echo and its performance evaluation in numerical simulations

The basic concept of distance measurement using the alternate transmission of two different codes based on the pulse-echo method has been used to obtain an extension of the measurable distance, in which the temporal resolution is not degraded in the one-code transmission. The reflected signals from the object are measured by two correlation signals. The received signal is correlated with each transmitted signal. The truncation and truncated interference noise of signals is generated in the cross-correlation function. Which is a part of signal components. The signal components are changed according to the transmit signal. In this paper, the SNRs of alternate transmission of different chirp signals is described and investigated. The highest SNR is achieved by the high bandwidth and long length of the transmitted signal. Different bandwidth of the chirp transmission is simulated. SNRs of the proposed method between the experiment and simulation is compare.

Section: Introductionmentioning

confidence: 99%

The evaluated signal-to-noise ratio for the alternate transmission of different chirp ultrasound to extend the measurable distance in the pulse-echo method

Leetang¹,

Hachiya

Hirata

2023

“…In the pulse-echo method, involving transmission of an acoustic pulse and determination of the time of flight (TOF) of the pulse, the pulse-propagation distance can be measured from the TOF and the speed of sound in the media. [1][2][3][4] The distance resolution is determined by the pulse width, predominantly depending on the bandwidths of transducers. However, in the case of a short pulse, the signal-to-noise ratio (SNR) of the received signal degrades despite the high distance resolution.…”

Section: Introductionmentioning

confidence: 99%

Selection on the combination of M-sequence codes in alternate transmission for extension of measurable distance

Leetang

Hirata

Hachiya

2019

In M-sequence pulse compression for acoustic distance measurement, a continuous signal modulated by the cyclic binary code in an M-sequence is transmitted. Then, the received signal is correlated with one cycle of the transmitted code. The time of flight for the estimation of the propagation distance is determined from the peak appeared in the cross-correlation function when both codes match. The temporal resolution of the measurement and the maximum measurable distance are determined by the cycle length of the transmitted signal and in a trade-off relationship. Alternate transmission of different M-sequence codes and cross-correlations with each code can extend the measurable distance without degradation of the temporal resolution. However, truncation noise in each code and truncated interference noise between codes are generated around correlation peaks. The patterns of these noises are varied by the combination of codes. Therefore, contamination by these noise can be suppressed by selecting suitable codes.

“…With different contact forces, the absolute threshold of hearing can be affected by more than 10 dB. 20) Unlike other transducers for mechanical systems using ultrasound [19][20][21][22][23][24][25][26][27][28][29][30][31][32] , a bone-conducted transducer is not used with matching layers or with rigid mounts. International standards on bone-conducted sound transducer calibration reflect the effect of contact force on bone-conducted sound.…”

Section: Introductionmentioning

confidence: 99%

Method of estimating contact force of bone-conducted sound transducer with a two-degrees-of-freedom vibrating model

Ogiso

Mizutani

Zempo

et al. 2019

In this paper, we propose a method of estimating the contact force of a bone-conducted sound transducer with a two-degrees-of-freedom vibrating model. First, the electrical impedance of the transducer was measured by varying the contact force applied to 12 human subjects. The model was fit to the measurement electrical impedance by changing the damping coefficient. The results showed that the model's damping coefficient is related to the contact force. The fitting was valid when the contact force was below than 3.0 N. Second, a contact force estimation method utilizing the relationship between the damping coefficient and the contact force was proposed. The contact force was estimated by estimating the damping coefficient from the measured impedance and calculating the corresponding contact force from the damping-contact force curve. The estimation results showed that the proposed method achieves reasonable accuracy compared to a previous method using a neural network. Also, the proposed method can be achieved with only two calibration conditions, 0.3 N and 0.5 N, by employing a physical model. This drastically reduces the calibration process compared to the previous methods.