Experimental investigation of parametric array for low frequency measurement system

2021 ◽  
Vol 150 (4) ◽  
pp. A126-A126
Author(s):  
Donghwan Jung ◽  
Jiyoung Song ◽  
J. S. Kim ◽  
Jaehyuk Lee
Keyword(s):  
Experimental Investigation ◽  
Measurement System ◽  
Low Frequency ◽  
Frequency Measurement ◽  
Parametric Array

scholarly journals Comparative Experimental Investigation on Optimal Parametric Array Types

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 5085
Author(s):  
Donghwan Jung ◽  
Jiyoung Song ◽  
Jeasoo Kim ◽  
Jaehyuk Lee
Keyword(s):  
Experimental Investigation ◽  
Low Frequency ◽  
Acoustic Properties ◽  
Dual Frequency ◽  
Small Aperture ◽  
Comparative Experimental Investigation ◽  
Source Level ◽  
Parametric Array ◽  
Acoustic Properties Of Materials ◽  
Water Tanks

As a sound transmitting device that relies on the nonlinearity of a medium, a parametric array (PA) can generate high-directivity low-frequency signals using a small aperture transducer and high-frequency signals. Despite their relatively low source level, the PA is frequently used to measure the acoustic properties of materials in low-frequency regions owing to their high directivity in confined acoustic water tanks. Therefore, methods for improving the source level of secondary signals are of interest. Currently, there are two driving methods for PA: the dual-frequency PA and the broadband PA with amplitude modulation. In this study, we share the results of an elaborate and comparative experimental investigation of these two driving methods. Comparisons are made and discussed in terms of the intensity of the generated secondary signal and its characteristics in the frequency domain. Based on these factors, we confirmed that the broadband PA was more suitable as the sound source of the low-frequency characteristic measurement system of acoustic materials.

scholarly journals A phase-locked loop using ESO-based loop filter for grid-connected converter: performance analysis

2021 ◽  
Author(s):  
Baoling Guo ◽  
Seddik Bacha ◽  
Mazen Alamir ◽  
Julien Pouget
Keyword(s):  
Performance Analysis ◽  
Frequency Domain ◽  
Low Frequency ◽  
Experimental Tests ◽  
Frequency Measurement ◽  
Phase Locked Loop ◽  
Frequency Domain Analysis ◽  
Loop Filter ◽  
Control Stability ◽  
Unbalanced Grid

AbstractAn extended state observer (ESO)-based loop filter is designed for the phase-locked loop (PLL) involved in a disturbed grid-connected converter (GcC). This ESO-based design enhances the performances and robustness of the PLL, and, therefore, improves control performances of the disturbed GcCs. Besides, the ESO-based LF can be applied to PLLs with extra filters for abnormal grid conditions. The unbalanced grid is particularly taken into account for the performance analysis. A tuning approach based on the well-designed PI controller is discussed, which results in a fair comparison with conventional PI-type PLLs. The frequency domain properties are quantitatively analysed with respect to the control stability and the noises rejection. The frequency domain analysis and simulation results suggest that the performances of the generated ESO-based controllers are comparable to those of the PI control at low frequency, while have better ability to attenuate high-frequency measurement noises. The phase margin decreases slightly, but remains acceptable. Finally, experimental tests are conducted with a hybrid power hardware-in-the-loop benchmark, in which balanced/unbalanced cases are both explored. The obtained results prove the effectiveness of ESO-based PLLs when applied to the disturbed GcC.

scholarly journals A sound card based multi-channel frequency measurement system

2006 ◽  
Vol 33 (3) ◽  
pp. 221-224 ◽  
Author(s):  
S. Groeger ◽  
G. Bison ◽  
P. E. Knowles ◽  
A. Weis
Keyword(s):  
Measurement System ◽  
Frequency Measurement ◽  
Sound Card

Covert Underwater Acoustic Communication System Using Parametric Array

2019 ◽  
Vol 53 (1) ◽  
pp. 20-26 ◽  
Author(s):  
Anbang Zhao ◽  
Yue Cheng ◽  
Tiansi An ◽  
Juan Hui
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Low Frequency ◽  
Nonlinear Behavior ◽  
Beam Width ◽  
Point Of View ◽  
Underwater Acoustic Communication ◽  
Water Tank ◽  
Narrow Beam ◽  
Underwater Acoustic ◽  
Parametric Array

AbstractA novel and efficient covert underwater acoustic (UWA) communication scheme using an acoustic parametric array and orthogonal frequency division multiplexing (OFDM) system is presented. The proposed system is robust and can easily be implemented in the ocean environment. The system is also very useful in military applications where the secrecy of transmission signal and location of the transmitter are extremely important. The paper exploits the difference frequency generated by the acoustic parametric array due to the nonlinear behavior of an underwater medium. Besides the lightness and compactness, the parametric array also possesses the advantage of being low-frequency, broadband, highly directive, and narrow beam with no side lobes. The narrow beam width also helps to secure the data from a spatial point of view. Experiments have been performed in a water tank, and the results are presented to show the effectiveness of the proposed scheme.

scholarly journals Photonics-Assisted Serial Channelized Radio-Frequency Measurement System With Nyquist-Bandwidth Detection

2014 ◽  
Vol 6 (6) ◽  
pp. 1-7 ◽  
Author(s):  
Hongwei Chen ◽  
Ruiyue Li ◽  
Cheng Lei ◽  
Ying Yu ◽  
Minghua Chen ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Measurement System ◽  
Frequency Measurement
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