scholarly journals A modified time delay spectrometry technique for underwater acoustic measurements

1985 ◽  
Vol 77 (S1) ◽  
pp. S70-S70
Author(s):  
Bjoern Brekke ◽  
O. B. Wilson
Keyword(s):  
Time Delay ◽  
Acoustic Measurements ◽  
Underwater Acoustic ◽  
Spectrometry Technique

scholarly journals Underwater Acoustic Time Delay Estimation Based on Envelope Differences of Correlation Functions

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 1259 ◽  
Author(s):  
Guodong Li ◽  
Jinsong Wu ◽  
Taolin Tang ◽  
Zhixin Chen ◽  
Jun Chen ◽  
...  
Keyword(s):  
Time Delay ◽  
Correlation Functions ◽  
Estimation Method ◽  
Digital Signal ◽  
Low Complexity ◽  
Time Delay Estimation ◽  
Delay Estimation ◽  
Estimation Errors ◽  
Underwater Acoustic ◽  
Amplitude Fluctuations

This paper proposes underwater acoustic time delay estimation based on the envelope differences of correlation functions (EDCF), which mitigates the delay estimation errors introduced by the amplitude fluctuations of the correlation function envelopes in the traditional correlation methods (CM). The performance of the proposed delay estimation method under different time values was analyzed, and the optimal difference time values are given. To overcome the influences of digital signal sampling intervals on time delay estimation, a digital time delay estimation approach with low complexity and high accuracy is proposed. The performance of the proposed time delay estimation was analyzed in underwater multipath channels. Finally, the accuracy of the delay estimation using this proposed method was demonstrated by experiments.

Digital time delay network for an active underwater acoustic coating

1993 ◽  
Vol 93 (3) ◽  
pp. 1613-1619 ◽  
Author(s):  
Thomas R. Howarth ◽  
Xiaoqi Bao ◽  
Robert Moser ◽  
Vijay K. Varadan ◽  
Vasundara V. Varadan
Keyword(s):  
Time Delay ◽  
Underwater Acoustic ◽  
Digital Time

Research on MAC Protocol for UWA Sensor Network

2013 ◽  
Vol 303-306 ◽  
pp. 236-241
Author(s):  
Wen Zhong Zhu
Keyword(s):  
Time Delay ◽  
Sensor Network ◽  
Mac Protocol ◽  
Propagation Delay ◽  
Spatial Multiplexing ◽  
Mac Protocols ◽  
The Other ◽  
Throughput Performance ◽  
Underwater Acoustic ◽  
Agent Protocol

The characteristics and environment of the underwater acoustic (UWA) sensor network require a MAC protocol to be suitable for the long propagation delay. So we put forward a suitable MAC protocol, referring to the AGENT protocol in this paper. We call this protocol C-AGENT-LPD, which means C-AGENT with Long Propagation Delay. And it makes full use of the spatial multiplexing of the UWA channel. Through the simulations, we can see that the protocol has better time delay and throughput performance than the other two MAC protocols.

scholarly journals Underwater Acoustic Measurements on Polyvinylidene Fluoride Transducers

1978 ◽  
Vol 5 (3) ◽  
pp. 149-157 ◽  
Author(s):  
B. Woodward ◽  
R. C. Chandra
Keyword(s):  
Polyvinylidene Fluoride ◽  
Characteristic Impedance ◽  
Thin Sheet ◽  
Piezoelectric Transducers ◽  
Thin Sheets ◽  
Acoustic Measurements ◽  
Underwater Acoustic ◽  
Source Level ◽  
Operation Parameters

Methods of making piezoelectric transducers from very thin sheets of polyvinylidene fluoride (PVDF) are discussed, together with techniques for calibrating these devices, particularly for underwater operation. Parameters measured include receiving response, source level, beamwidth, characteristic impedance and variation of impedance with frequency. Consideration is also given to the dependence of receiving response on the poling fields and temperatures used in making PVDF transducers. Because of their broadband response thin sheet PVDF transducers have been shown to be ideal for monitoring the true form of acoustic pulses underwater.

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