Pub Date : 1900-01-01DOI: 10.1109/COA.2016.7535803
S. Holm, Vikas Pandey
Attenuation of compressional and shear waves in sediments often follows power laws with near linear variation with frequency. This cannot be modeled with viscous or relaxation wave equations, but more general temporal memory operators in the wave equation can describe such behavior. These operators can be justified in four ways: 1) Power laws for attenuation with exponents other than two correspond to the use of convolution operators with a kernel which is a power law in time. 2) The corresponding constitutive equation is also a convolution, often with a temporal power law function. 3) It is also equivalent to an infinite set of relaxation processes which can be formulated via the complex compressibility. 4) The constitutive equation can also be expressed as an infinite sum of higher order derivatives. We also analyze a grain-shearing model for propagation of waves in saturated, unconsolidated granular materials. It is expressed via a spring damper model with time-varying damping. It turns out that it results in a fractional Kelvin-Voigt wave equation and a fractional diffusion equation for the compressional and shear waves respectively, giving a new perspective for understanding and interpreting this model.
{"title":"Wave propagation in marine sediments expressed by fractional wave and diffusion equations","authors":"S. Holm, Vikas Pandey","doi":"10.1109/COA.2016.7535803","DOIUrl":"https://doi.org/10.1109/COA.2016.7535803","url":null,"abstract":"Attenuation of compressional and shear waves in sediments often follows power laws with near linear variation with frequency. This cannot be modeled with viscous or relaxation wave equations, but more general temporal memory operators in the wave equation can describe such behavior. These operators can be justified in four ways: 1) Power laws for attenuation with exponents other than two correspond to the use of convolution operators with a kernel which is a power law in time. 2) The corresponding constitutive equation is also a convolution, often with a temporal power law function. 3) It is also equivalent to an infinite set of relaxation processes which can be formulated via the complex compressibility. 4) The constitutive equation can also be expressed as an infinite sum of higher order derivatives. We also analyze a grain-shearing model for propagation of waves in saturated, unconsolidated granular materials. It is expressed via a spring damper model with time-varying damping. It turns out that it results in a fractional Kelvin-Voigt wave equation and a fractional diffusion equation for the compressional and shear waves respectively, giving a new perspective for understanding and interpreting this model.","PeriodicalId":155481,"journal":{"name":"2016 IEEE/OES China Ocean Acoustics (COA)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114680581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/COA.2016.7535751
Hongyu Cui, Youwen Zhang, Xin Liu, Dajun Sun
Underwater acoustic sensor networks (UASN) are a promising research area, due to the wide range of aquatic applications, such as pollution monitoring and submarine detection. The realistic evaluation of the novel UASN protocols and algorithms in the field trials is too expensive and time-consuming. Therefore, standard simulation and emulation platforms of UASN are quite required, and can efficiently reduce the development cycle of novel methods. In this paper, we introduce the platforms developed by our laboratory, which are based on the well-known ns2 and ns-miracle simulators, with the layered structure supporting the cross-layer signaling. The simulation platform works on the personal computer equipped with linux operating system. The architecture of the platform is divided into four layers: application layer, routing layer, medium access layer, and physical layer. The emulation platform works on the embedded devices in the sea trial, such as the OMAPL138 DSP+ARM dual-processor of Texas Instrument company. To guarantee the consistency, the programming codes of networking protocols in the emulation platform can be adopted directly from those in the simulation platform. Finally, in this paper, we present the simulation and emulation results to verify the accuracy and efficiency of the platforms.
{"title":"The simulation and emulation platforms of underwater acoustic sensor networks","authors":"Hongyu Cui, Youwen Zhang, Xin Liu, Dajun Sun","doi":"10.1109/COA.2016.7535751","DOIUrl":"https://doi.org/10.1109/COA.2016.7535751","url":null,"abstract":"Underwater acoustic sensor networks (UASN) are a promising research area, due to the wide range of aquatic applications, such as pollution monitoring and submarine detection. The realistic evaluation of the novel UASN protocols and algorithms in the field trials is too expensive and time-consuming. Therefore, standard simulation and emulation platforms of UASN are quite required, and can efficiently reduce the development cycle of novel methods. In this paper, we introduce the platforms developed by our laboratory, which are based on the well-known ns2 and ns-miracle simulators, with the layered structure supporting the cross-layer signaling. The simulation platform works on the personal computer equipped with linux operating system. The architecture of the platform is divided into four layers: application layer, routing layer, medium access layer, and physical layer. The emulation platform works on the embedded devices in the sea trial, such as the OMAPL138 DSP+ARM dual-processor of Texas Instrument company. To guarantee the consistency, the programming codes of networking protocols in the emulation platform can be adopted directly from those in the simulation platform. Finally, in this paper, we present the simulation and emulation results to verify the accuracy and efficiency of the platforms.","PeriodicalId":155481,"journal":{"name":"2016 IEEE/OES China Ocean Acoustics (COA)","volume":"154 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114898803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/COA.2016.7535779
Z. Zhigang, Bian Hongyu, Song Ziqi
In underwater object detection and identification of an unmanned underwater vehicle (UUV), high-frequency 2-D imaging sonar is an effective device for measuring distance accurately. Forward-looking sonar records a sequence of images of the object's surfaces, which continuously change as the UUV moves around the target. A single image usually describes partial structures or local regions of a large object surface, such as for ship hull inspection, and the surface detection of a pier or dam. To improve the capability of object detection and identification, we focus on the details and textures of sonar images, and use the image fusion method to take advantage of complementary information among redundant images. In our work, we consider the features of a sequence of images taken from different views, and which have different target intensities, object shapes and noise distribution. We present a sonar image fusion method based on directional filters banks and morphological wavelets, which combines the features of multiresolution wavelet analysis and nonlinear filters. Firstly, the noisy sonar images are transformed into the morphological wavelet domain, which can effectively decrease image noise. Then the high frequencies of the source images are fed into a directional filters bank, which uses the directional decomposition approach to provide exact details of the image whilst retaining the unchanged low frequency content. Finally, we fuse the multiscale and directions parts into the transforming domain, and reconstruct the fusion image. The result of applying this method to a sequence of sonar images from multi-views indicates that the fusion image can effectively describe the extra details in source images in terms of multiresolution and direction. It is also good at suppressing noise, especially for images with a higher noise level. Comparison of the experiments and real data supports our conclusions from subjective and objective evaluation, and shows that the regions in the fused images are effectively repaired and image quality is evidently improved.
{"title":"A multi-view sonar image fusion method based on the morphological wavelet and directional filters","authors":"Z. Zhigang, Bian Hongyu, Song Ziqi","doi":"10.1109/COA.2016.7535779","DOIUrl":"https://doi.org/10.1109/COA.2016.7535779","url":null,"abstract":"In underwater object detection and identification of an unmanned underwater vehicle (UUV), high-frequency 2-D imaging sonar is an effective device for measuring distance accurately. Forward-looking sonar records a sequence of images of the object's surfaces, which continuously change as the UUV moves around the target. A single image usually describes partial structures or local regions of a large object surface, such as for ship hull inspection, and the surface detection of a pier or dam. To improve the capability of object detection and identification, we focus on the details and textures of sonar images, and use the image fusion method to take advantage of complementary information among redundant images. In our work, we consider the features of a sequence of images taken from different views, and which have different target intensities, object shapes and noise distribution. We present a sonar image fusion method based on directional filters banks and morphological wavelets, which combines the features of multiresolution wavelet analysis and nonlinear filters. Firstly, the noisy sonar images are transformed into the morphological wavelet domain, which can effectively decrease image noise. Then the high frequencies of the source images are fed into a directional filters bank, which uses the directional decomposition approach to provide exact details of the image whilst retaining the unchanged low frequency content. Finally, we fuse the multiscale and directions parts into the transforming domain, and reconstruct the fusion image. The result of applying this method to a sequence of sonar images from multi-views indicates that the fusion image can effectively describe the extra details in source images in terms of multiresolution and direction. It is also good at suppressing noise, especially for images with a higher noise level. Comparison of the experiments and real data supports our conclusions from subjective and objective evaluation, and shows that the regions in the fused images are effectively repaired and image quality is evidently improved.","PeriodicalId":155481,"journal":{"name":"2016 IEEE/OES China Ocean Acoustics (COA)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123419891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/COA.2016.7535735
Zhijie Yue, Ting Wang
AUV underwater docking is an effective way to provide energy supplement and complete information exchange with an AUV, which in turn allows an AUV make long-term missions in the water and avoid the need for repeated launching and retrieval. This paper proposes a new navigation and positioning system, which measures distance by underwater acoustic communication and by USBL. It can be used for underwater AUV remote positioning and guiding, so that an AUV can find the underwater feeder station in order to complete energy supply and exchange of information. The system consists of a T/R transducer at the end of the AUV; an electronic cabin within the chamber of the AUV, and, a T/R transducer USBL array and watertight electronic cabin at the end of underwater feeder station. For the hardware, the T/R transducers operating band is 10 kHz ~ 14kHz with overflow structure; there is a USBL array of conical structures; and, an electronic compartment which uses DSP, FPGA, MSP430 joint architecture. For the algorithms, the underwater acoustic communication equipment uses both LFM signal head and DSSS communication algorithms in order to obtain distance measurement results. The USBL array uses M sequence modulated signals emitted from the AUV terminal in order to measure direction. The system performance was tested in a lake, In the static case, the range accuracy was 0.2m ± 0.05%, and the orientation of the measurement accuracy is 0.3°. In the dynamic case, the positioning results were compared with GPS Real-time results, and their positioning track fitted well with each other.
{"title":"Navigation and positioning system design of an AUV underwater docking","authors":"Zhijie Yue, Ting Wang","doi":"10.1109/COA.2016.7535735","DOIUrl":"https://doi.org/10.1109/COA.2016.7535735","url":null,"abstract":"AUV underwater docking is an effective way to provide energy supplement and complete information exchange with an AUV, which in turn allows an AUV make long-term missions in the water and avoid the need for repeated launching and retrieval. This paper proposes a new navigation and positioning system, which measures distance by underwater acoustic communication and by USBL. It can be used for underwater AUV remote positioning and guiding, so that an AUV can find the underwater feeder station in order to complete energy supply and exchange of information. The system consists of a T/R transducer at the end of the AUV; an electronic cabin within the chamber of the AUV, and, a T/R transducer USBL array and watertight electronic cabin at the end of underwater feeder station. For the hardware, the T/R transducers operating band is 10 kHz ~ 14kHz with overflow structure; there is a USBL array of conical structures; and, an electronic compartment which uses DSP, FPGA, MSP430 joint architecture. For the algorithms, the underwater acoustic communication equipment uses both LFM signal head and DSSS communication algorithms in order to obtain distance measurement results. The USBL array uses M sequence modulated signals emitted from the AUV terminal in order to measure direction. The system performance was tested in a lake, In the static case, the range accuracy was 0.2m ± 0.05%, and the orientation of the measurement accuracy is 0.3°. In the dynamic case, the positioning results were compared with GPS Real-time results, and their positioning track fitted well with each other.","PeriodicalId":155481,"journal":{"name":"2016 IEEE/OES China Ocean Acoustics (COA)","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129076346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/COA.2016.7535690
Yu Tongkui, Liu Wen-shuai, Shi Sheng-guo, Yuan Shuhua
The resonant of the ship shell is the important aspect for reflecting the natural characteristic frequency of radiated noise of the ship shell. To master the frequency spectrum characteristics of the ship radiated noise and analyze its changing regularity with ship speeds, there is great significance for distinguishing the line spectra of acoustic field which is stimulated by mechanical equipment or shell resonance. When the natural frequency of the mechanical equipment is equal to the shell of the ship, it might stimulate the resonance of the shell. It is difficult to distinguish the characteristic frequency of the resonant frequency and the equipment when the spectrum resolution is 1 Hz, since the line spectrum is only reflected as f Hz. However, with zoom spectrum analysis, it can be distinguished as two different line spectra when the resolution of spectrum is 0.1 Hz or higher. They are f1 Hz and f2 Hz respectively. Using a line spectrum extraction technique, we extract three line spectra: f, f1 and f2 under the conditions of different frequency resolution; and, then their real-time phases are received, which are represented as ψ, ψ1 and ψ. Finally, the differences of ψ and ψ1, ψ and ψ2 are calculated. The changing regularity of the above two differences with time are entirely opposite. In order to verify the validity of this method, a test is carried out with the Beidiao 991 ship. In the pump chamber, a high-power motor is installed on the shell, and its working frequency is the same as the natural frequency of the shell. The test results show that the method can effectively judge whether or not the shell of ship is resonant.
{"title":"A new method for distinguishing the resonant of shell","authors":"Yu Tongkui, Liu Wen-shuai, Shi Sheng-guo, Yuan Shuhua","doi":"10.1109/COA.2016.7535690","DOIUrl":"https://doi.org/10.1109/COA.2016.7535690","url":null,"abstract":"The resonant of the ship shell is the important aspect for reflecting the natural characteristic frequency of radiated noise of the ship shell. To master the frequency spectrum characteristics of the ship radiated noise and analyze its changing regularity with ship speeds, there is great significance for distinguishing the line spectra of acoustic field which is stimulated by mechanical equipment or shell resonance. When the natural frequency of the mechanical equipment is equal to the shell of the ship, it might stimulate the resonance of the shell. It is difficult to distinguish the characteristic frequency of the resonant frequency and the equipment when the spectrum resolution is 1 Hz, since the line spectrum is only reflected as f Hz. However, with zoom spectrum analysis, it can be distinguished as two different line spectra when the resolution of spectrum is 0.1 Hz or higher. They are f1 Hz and f2 Hz respectively. Using a line spectrum extraction technique, we extract three line spectra: f, f1 and f2 under the conditions of different frequency resolution; and, then their real-time phases are received, which are represented as ψ, ψ1 and ψ. Finally, the differences of ψ and ψ1, ψ and ψ2 are calculated. The changing regularity of the above two differences with time are entirely opposite. In order to verify the validity of this method, a test is carried out with the Beidiao 991 ship. In the pump chamber, a high-power motor is installed on the shell, and its working frequency is the same as the natural frequency of the shell. The test results show that the method can effectively judge whether or not the shell of ship is resonant.","PeriodicalId":155481,"journal":{"name":"2016 IEEE/OES China Ocean Acoustics (COA)","volume":"140 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121001406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/COA.2016.7535722
Z. Minghui, Sun Hui, S. Tielin, Chen Wenjian, Zhang Tian-hang
Underwater target acoustic scattering is an important aspect of underwater acoustic research. Research on the elastic scattering wave is related to the wave dispersion curves and the exit angle, but the excited condition of a Lamb wave is rarely discussed in the context of elastic plates. The energy distribution for the reflected Lamb waves of several modes when Lamb waves of other anti-symmetric modes are formed by reflection at the end face of an elastic plate is also rarely discussed. However, the research concentrating on the excitation condition of Lamb waves and mode conversion at the end face of a submerged elastic plate can be the basis for target recognition. Based on R.D. Mindlin Hamilton's principle and using an orthogonal complete feature, the frequency dispersion equation of a Lamb wave is derived for an elastic plate in a vacuum; and water, phase velocity, attenuation coefficients and group velocity dispersion curves are obtained. Analysis of the energy ratio between each of two anti-symmetric mode backward Lamb waves resulting from mode conversion when an anti-symmetric Lamb wave is incident at the end face of the plate in single mode is derived. The scattering wave of a submerged elastic plate is measured experimentally, which shows that only the incident anti-symmetric Lamb wave at the critical angle of one mode can directly excite a Lamb wave of this mode in the elastic plate, Lamb waves of other anti-symmetric modes are formed by reflection at the end face of the elastic plate. There is also no energy change between a symmetric Lamb wave and an anti-symmetric Lamb wave, even with mode conversion, if the waves are reflected at the end of the elastic plate. Combined with radiation efficiency of submerged elastic plate energy ratio between each two anti-symmetric mode backward lamb waves resulted from mode conversion when anti-symmetric lamb wave incident at the end face of plate in single mode confirmed validity of the analysis results.
{"title":"Research on mode conversion of lamb wave at dip end face of elastic plate","authors":"Z. Minghui, Sun Hui, S. Tielin, Chen Wenjian, Zhang Tian-hang","doi":"10.1109/COA.2016.7535722","DOIUrl":"https://doi.org/10.1109/COA.2016.7535722","url":null,"abstract":"Underwater target acoustic scattering is an important aspect of underwater acoustic research. Research on the elastic scattering wave is related to the wave dispersion curves and the exit angle, but the excited condition of a Lamb wave is rarely discussed in the context of elastic plates. The energy distribution for the reflected Lamb waves of several modes when Lamb waves of other anti-symmetric modes are formed by reflection at the end face of an elastic plate is also rarely discussed. However, the research concentrating on the excitation condition of Lamb waves and mode conversion at the end face of a submerged elastic plate can be the basis for target recognition. Based on R.D. Mindlin Hamilton's principle and using an orthogonal complete feature, the frequency dispersion equation of a Lamb wave is derived for an elastic plate in a vacuum; and water, phase velocity, attenuation coefficients and group velocity dispersion curves are obtained. Analysis of the energy ratio between each of two anti-symmetric mode backward Lamb waves resulting from mode conversion when an anti-symmetric Lamb wave is incident at the end face of the plate in single mode is derived. The scattering wave of a submerged elastic plate is measured experimentally, which shows that only the incident anti-symmetric Lamb wave at the critical angle of one mode can directly excite a Lamb wave of this mode in the elastic plate, Lamb waves of other anti-symmetric modes are formed by reflection at the end face of the elastic plate. There is also no energy change between a symmetric Lamb wave and an anti-symmetric Lamb wave, even with mode conversion, if the waves are reflected at the end of the elastic plate. Combined with radiation efficiency of submerged elastic plate energy ratio between each two anti-symmetric mode backward lamb waves resulted from mode conversion when anti-symmetric lamb wave incident at the end face of plate in single mode confirmed validity of the analysis results.","PeriodicalId":155481,"journal":{"name":"2016 IEEE/OES China Ocean Acoustics (COA)","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121376064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/COA.2016.7535675
Jian Li, X. Luo, Mingsheng Gao, Kai Xie, Defu Zhou
Matched-field processing is an underwater acoustics signal processing technology which combines oceanic physical acoustics technology and signal processing technology. The excellent performance of the matched field processing makes it a hot topic of research. Matched-mode processing is a matching approach working in mode space. Unlike matched-field processing, matched-mode processing can only extract the modes which have little relationship about the environment mismatch (whereas matched-field processing uses all modes). The MMP method reduces the sensitivity to environmental mismatches. In this paper, we have designed and carried out simulation experiments which show that more accurate positioning results can be obtained by carefully selecting the appropriate mode that is not sensitive to the environmental mismatch.
{"title":"Simulation research on matched-mode processor in mismatch environmental","authors":"Jian Li, X. Luo, Mingsheng Gao, Kai Xie, Defu Zhou","doi":"10.1109/COA.2016.7535675","DOIUrl":"https://doi.org/10.1109/COA.2016.7535675","url":null,"abstract":"Matched-field processing is an underwater acoustics signal processing technology which combines oceanic physical acoustics technology and signal processing technology. The excellent performance of the matched field processing makes it a hot topic of research. Matched-mode processing is a matching approach working in mode space. Unlike matched-field processing, matched-mode processing can only extract the modes which have little relationship about the environment mismatch (whereas matched-field processing uses all modes). The MMP method reduces the sensitivity to environmental mismatches. In this paper, we have designed and carried out simulation experiments which show that more accurate positioning results can be obtained by carefully selecting the appropriate mode that is not sensitive to the environmental mismatch.","PeriodicalId":155481,"journal":{"name":"2016 IEEE/OES China Ocean Acoustics (COA)","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134584104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/COA.2016.7535728
Liu Wei, H. Wentao, Wei Yi-bing, C. Xiaobao
Optical fiber hydrophones have many technical advantages, such as: large dynamic range, no electricity in the wet-end, small diameter under zero-buoyancy restriction, and so on. These merits make the optical fiber hydrophone more suitable to towed array for small vehicle. But the problem is that the optical fiber hydrophone outputs more extraneous noise than the piezoelectricity hydrophone when used in a towed array, due to its sensing mechanism. Aimed at this, a noise reduction method based on F-K transform is proposed in this paper in order to increase the Signal to Noise Ratio (SNR). Together with the multi-scale filter and Radon transform, most noise is removed and the signal components are reserved. The method is validated by both simulation and sea experiment data, and the results show that in the 80-120Hz bandwidth this method improves SNR by about 4~9dB.
{"title":"A noise reduction method based on F-K transform for optical fiber hydrophone towed array","authors":"Liu Wei, H. Wentao, Wei Yi-bing, C. Xiaobao","doi":"10.1109/COA.2016.7535728","DOIUrl":"https://doi.org/10.1109/COA.2016.7535728","url":null,"abstract":"Optical fiber hydrophones have many technical advantages, such as: large dynamic range, no electricity in the wet-end, small diameter under zero-buoyancy restriction, and so on. These merits make the optical fiber hydrophone more suitable to towed array for small vehicle. But the problem is that the optical fiber hydrophone outputs more extraneous noise than the piezoelectricity hydrophone when used in a towed array, due to its sensing mechanism. Aimed at this, a noise reduction method based on F-K transform is proposed in this paper in order to increase the Signal to Noise Ratio (SNR). Together with the multi-scale filter and Radon transform, most noise is removed and the signal components are reserved. The method is validated by both simulation and sea experiment data, and the results show that in the 80-120Hz bandwidth this method improves SNR by about 4~9dB.","PeriodicalId":155481,"journal":{"name":"2016 IEEE/OES China Ocean Acoustics (COA)","volume":"268 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133242014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/COA.2016.7535800
Chao Bai, H. Ren, Jie Li
Exploration and development of the ocean relies on underwater acoustic communication. However, the intrinsic characteristics of the underwater channel require that the communication system can cope with several physical constraints, such as more serious multipath propagation, limited frequency band, complex ambient noises, interference, time-varying characteristics and significant Doppler frequency shift. These features restrict the development of low Bit Error Rate (BER) underwater acoustic communication. In this paper, we propose a novel differential chaos shift keying (DCSK) scheme based on a hybrid chaotic system to obtain a better BER performance in underwater acoustic channels. In this scheme, the chaotic carrier is generated by a hybrid system rather than the traditional chaotic map. A corresponding match filter is used to decrease the effect of ambient noises at the receiver end. Compared with some existing methods, the BER performance of the proposed scheme is better.
{"title":"A differential chaos-shift keying scheme based on hybrid system for underwater acoustic communication","authors":"Chao Bai, H. Ren, Jie Li","doi":"10.1109/COA.2016.7535800","DOIUrl":"https://doi.org/10.1109/COA.2016.7535800","url":null,"abstract":"Exploration and development of the ocean relies on underwater acoustic communication. However, the intrinsic characteristics of the underwater channel require that the communication system can cope with several physical constraints, such as more serious multipath propagation, limited frequency band, complex ambient noises, interference, time-varying characteristics and significant Doppler frequency shift. These features restrict the development of low Bit Error Rate (BER) underwater acoustic communication. In this paper, we propose a novel differential chaos shift keying (DCSK) scheme based on a hybrid chaotic system to obtain a better BER performance in underwater acoustic channels. In this scheme, the chaotic carrier is generated by a hybrid system rather than the traditional chaotic map. A corresponding match filter is used to decrease the effect of ambient noises at the receiver end. Compared with some existing methods, the BER performance of the proposed scheme is better.","PeriodicalId":155481,"journal":{"name":"2016 IEEE/OES China Ocean Acoustics (COA)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129308793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/COA.2016.7535658
Zhu Bibo, C. Weihua, Jianhai Xia
In marine engineering surveying, when we control a towed synthetic aperture sonar in an uniform linear state, the survey results appear with many motion errors because of the random and multi-dimensional position fluctuation of the towed platform. A motion error estimation method based on seafloor tracking is studied in order to estimate these errors. Firstly, sonar echo data is obtained by wideband signal matched filter processing from different launch positions. According to the energy amplitude mutation, characteristics of the seabed echo we can deduce the seafloor position and eliminate abnormal values due to seafloor interface stationarity. Secondly, the approximate positional change curve of the towed platform is calculated from various sensor data. Thirdly, we can intercept the echo data from adjacent arrays in the same transmission period, according to the temporal correlation of echo data near the seafloor. The residual pitch angle is estimated by the shear average autofocus algorithm. By intercepting the echo data from redundant arrays in the adjacent transmission period - and on the basis of spatial redundancy of echo data near the seafloor - it is possible to estimate the residual heave values of the towed platform by use of the redundant phase center algorithm. In the meantime, the least square method is used to fit the linear phase error of pitch angle causing by assembly technology. Finally, the motion error of the echo data in different launch positions is finely compensated. The result of simulation and sea trial proves that the method in this paper is correct in principle and provides high engineering value.
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