Ultrasonic beam focusing through tissue inhomogeneities with a time reversal mirror: application to transskull therapy

1996 ◽  
Vol 43 (6) ◽  
pp. 1122-1129 ◽  
Author(s):  
J.-L. Thomas ◽  
M.A. Fink
Keyword(s):  
Time Reversal ◽  
Ultrasonic Beam ◽  
Beam Focusing ◽  
Time Reversal Mirror

INVESTIGATION OF ULTRASONIC BEAM FOCUSING EFFECTS FOR INHOMOGENEOUS MEDIA USING THE TIME REVERSAL METHOD

2009 ◽  
Author(s):  
H. Jeong ◽  
J.-S. Lee ◽  
Y.-H. Jeong ◽  
S.-M. Bae ◽  
C. H. Lee ◽  
...  
Keyword(s):  
Time Reversal ◽  
Inhomogeneous Media ◽  
Ultrasonic Beam ◽  
Beam Focusing

scholarly journals M-ary nonlinear sine chirp spread spectrum for underwater acoustic communication based on virtual time-reversal mirror method

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Songzuo Liu ◽  
Habib Hussain Zuberi ◽  
Yi Lou ◽  
Muhmmad Bilal Farooq ◽  
Shahabuddin Shaikh ◽  
...  
Keyword(s):  
Acoustic Communication ◽  
Time Reversal ◽  
Spread Spectrum ◽  
Underwater Acoustic Communication ◽  
Half Cycle ◽  
Spreading Factor ◽  
Underwater Acoustic ◽  
Virtual Time ◽  
Chirp Spread Spectrum ◽  
Time Reversal Mirror

AbstractLinear chirp spread spectrum technique is widely used in underwater acoustic communication because of their resilience to high multipath and Doppler shift. Linear frequency modulated signal requires a high spreading factor to nearly reach orthogonality between two pairs of signals. On the other hand, nonlinear chirp spread spectrum signals can provide orthogonality at a low spreading factor. As a result, it improves spectral efficiency and is more insensitive to Doppler spread than the linear counterpart. To achieve a higher data rate, we propose two variants (half cycle sine and full cycle sine) of the M-ary nonlinear sine chirp spread spectrum technique based on virtual time-reversal mirror (VTRM). The proposed scheme uses different frequency bands to transmit chirp, and VTRM is used to improve the bit error rate due to high multipath. Its superior Doppler sensitivity makes it suitable for underwater acoustic communication. Furthermore, the proposed method uses a simple, low-power bank of matched filters; thus, it reduces the overall system complexity. Simulations are performed in different underwater acoustic channels to verify the robustness of the proposed scheme.

Demonstration of a high-frequency acoustic barrier with a time-reversal mirror

2003 ◽  
Vol 28 (2) ◽  
pp. 246-249 ◽  
Author(s):  
H. Song ◽  
W.A. Kuperman ◽  
W.S. Hodgkiss ◽  
T. Akal ◽  
P. Guerrini
Keyword(s):  
Time Reversal ◽  
High Frequency ◽  
Time Reversal Mirror

Environmentally adaptive reverberation nulling using a time reversal mirror

2004 ◽  
Vol 116 (2) ◽  
pp. 762-768 ◽  
Author(s):  
H. C. Song ◽  
S. Kim ◽  
W. S. Hodgkiss ◽  
W. A. Kuperman
Keyword(s):  
Time Reversal ◽  
Time Reversal Mirror

scholarly journals An Underwater Time Reversal Communication Method Using Symbol-Based Doppler Compensation with a Single Sound Pressure Sensor

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3279
Author(s):  
Anbang Zhao ◽  
Caigao Zeng ◽  
Juan Hui ◽  
Lin Ma ◽  
Xuejie Bi
Keyword(s):  
Time Reversal ◽  
Multipath Propagation ◽  
Single Element ◽  
Communication Performance ◽  
Songhua River ◽  
Communication Method ◽  
Doppler Effects ◽  
Communication Experiment ◽  
Time Reversal Mirror ◽  
Doppler Compensation

Due to the significant multipath and Doppler effects in the underwater acoustic (UWA) channel, the quality of the received signal is degraded, which seriously affects the performance of UWA communication. The paper proposes a time reversal UWA communication method combined with a symbol-based Doppler compensation (SBDC) technique to solve those problems. A single element time reversal mirror (TRM) is used to realize channel equalization and mitigate the inter-symbol interference (ISI) resulting from multipath propagation. The SBDC technique is subsequently used to compensate Doppler effects in the received signal, thereby reducing the bit error rate (BER) and improving the communication performance. In order to verify the performance of the proposed communication method, some simulations with real sounding channels were performed. Moreover, a field UWA communication experiment was conducted in the Songhua River (Harbin, China). The UWA communication experiment achieves nearly error-free performance with a communication rate of 100 bit/s in the bandwidth of 2 kHz. The results of the experiment demonstrate the feasibility and robustness of the proposed UWA communication method.

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