Pub Date : 2002-10-29DOI: 10.1109/OCEANS.2002.1191855
C. Barron, L. Smedstad
One of the primary concerns driving the development of U.S. Navy global models has been improved performance and nesting support in shelf and nearshore regions with short notice applicability anywhere on the globe. A global implementation of the Navy Coastal Ocean Model (NCOM) is a product of some of the efforts to meet this need. One purpose of Global NCOM is to provide a global capability for initializing, nesting, and evaluating fixed and relocatable coastal ocean models. In support of that objective, a database of river flow estimates is needed. Perry et al. (1996) provides a start with estimates of annual mean river discharges for 981 of the largest global rivers. However, many rivers exhibit a strong seasonal variability, which we would like to reflect in our ocean models. Through the use of multiple Internet sources and published data sets we have expanded on the Perry (1996) data to provide a global database of monthly mean river discharge and incorporated this data in global and nested NCOM runs. Where sufficient data is unavailable to construct monthly means, a seasonal cycle is imputed from nearby rivers and scaled to the appropriate annual mean. Real time discharge rates are routinely available for almost no rivers outside of the United States, so a monthly mean is likely to be the most appropriate estimate of real time flow for analyses and forecasts in most areas. The monthly river outflow can contribute to more accurate seasonal representation of areas near coastlines. Seasonality particularly affects the polar areas, where river outflow can become quite small during winter months and quite large during the summer melting season. Multiannual daily USGS observations for selected US rivers are used to quantify the improvement in estimation of daily flow by the monthly means versus a multiannual mean. Case studies examine the impact of river input into NCOM.
推动美国海军全球模型发展的主要问题之一是提高在大陆架和近岸地区的性能和嵌套支持，并在全球任何地方具有短时间适用性。海军沿海海洋模型(NCOM)的全球实施是满足这一需求的一些努力的产物。Global NCOM的目的之一是提供初始化、嵌套和评估固定和可重新定位的沿海海洋模型的全局能力。为了支持这一目标，需要一个河流流量估计数据库。Perry et al.(1996)首先对全球981条最大河流的年平均河流流量进行了估计。然而，许多河流表现出强烈的季节性变化，我们希望在我们的海洋模型中反映出来。通过使用多种互联网资源和已发布的数据集，我们对Perry(1996)数据进行了扩展，以提供月度平均河流流量的全球数据库，并将这些数据纳入全球和嵌套的NCOM运行中。如果没有足够的数据来构建月平均值，则从附近的河流中推算出一个季节周期，并按比例换算成适当的年平均值。美国以外的河流几乎没有实时流量的常规数据，因此在大多数地区，月度平均值可能是对实时流量进行分析和预测的最合适的估计。每月的河流流出量可以更准确地反映海岸线附近地区的季节性情况。季节性特别影响极地地区，那里的河流流量在冬季可能变得相当小，而在夏季融化季节则相当大。美国地质勘探局对选定的美国河流的多年每日观测数据用于量化按月平均与多年平均估算日流量的改进。案例研究考察了河流输入对NCOM的影响。
{"title":"Global river inflow with Navy Coastal Ocean Model","authors":"C. Barron, L. Smedstad","doi":"10.1109/OCEANS.2002.1191855","DOIUrl":"https://doi.org/10.1109/OCEANS.2002.1191855","url":null,"abstract":"One of the primary concerns driving the development of U.S. Navy global models has been improved performance and nesting support in shelf and nearshore regions with short notice applicability anywhere on the globe. A global implementation of the Navy Coastal Ocean Model (NCOM) is a product of some of the efforts to meet this need. One purpose of Global NCOM is to provide a global capability for initializing, nesting, and evaluating fixed and relocatable coastal ocean models. In support of that objective, a database of river flow estimates is needed. Perry et al. (1996) provides a start with estimates of annual mean river discharges for 981 of the largest global rivers. However, many rivers exhibit a strong seasonal variability, which we would like to reflect in our ocean models. Through the use of multiple Internet sources and published data sets we have expanded on the Perry (1996) data to provide a global database of monthly mean river discharge and incorporated this data in global and nested NCOM runs. Where sufficient data is unavailable to construct monthly means, a seasonal cycle is imputed from nearby rivers and scaled to the appropriate annual mean. Real time discharge rates are routinely available for almost no rivers outside of the United States, so a monthly mean is likely to be the most appropriate estimate of real time flow for analyses and forecasts in most areas. The monthly river outflow can contribute to more accurate seasonal representation of areas near coastlines. Seasonality particularly affects the polar areas, where river outflow can become quite small during winter months and quite large during the summer melting season. Multiannual daily USGS observations for selected US rivers are used to quantify the improvement in estimation of daily flow by the monthly means versus a multiannual mean. Case studies examine the impact of river input into NCOM.","PeriodicalId":431594,"journal":{"name":"OCEANS '02 MTS/IEEE","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133141148","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 : 2002-10-29DOI: 10.1109/OCEANS.2002.1191914
S. Negahdaripour, H. Madjidi
We address the deployment of stereovision imaging for underwater 3D mapping. A key component in system performance is the ability to determine the vehicle's position during data acquisition, ensuring that the images are acquired at desired positions along the pre-planned trajectory. We investigate the use of stereo images from the integration of incremental motions between consecutive frames. This is achieved within a complete framework, comprising (1) suitable trajectories to be executed for data collection, (2) data processing for mapping as well as for trajectory following and recursive alignment of images, and finally (3) 3D mapping by the fusion of various visual cues, including motion and stereo within a Kalman filter. The computational requirements of the system are evaluated, formalizing how online processing performance may be achieved. Experiments with underwater images are presented to demonstrate how the trajectory estimation is improved by the proposed alignment scheme.
{"title":"A stereo imaging framework in 3-D mapping of benthic habitats and seafloor structures","authors":"S. Negahdaripour, H. Madjidi","doi":"10.1109/OCEANS.2002.1191914","DOIUrl":"https://doi.org/10.1109/OCEANS.2002.1191914","url":null,"abstract":"We address the deployment of stereovision imaging for underwater 3D mapping. A key component in system performance is the ability to determine the vehicle's position during data acquisition, ensuring that the images are acquired at desired positions along the pre-planned trajectory. We investigate the use of stereo images from the integration of incremental motions between consecutive frames. This is achieved within a complete framework, comprising (1) suitable trajectories to be executed for data collection, (2) data processing for mapping as well as for trajectory following and recursive alignment of images, and finally (3) 3D mapping by the fusion of various visual cues, including motion and stereo within a Kalman filter. The computational requirements of the system are evaluated, formalizing how online processing performance may be achieved. Experiments with underwater images are presented to demonstrate how the trajectory estimation is improved by the proposed alignment scheme.","PeriodicalId":431594,"journal":{"name":"OCEANS '02 MTS/IEEE","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128838209","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 : 2002-10-29DOI: 10.1109/OCEANS.2002.1192015
D. Phelps, S. Dugelay
This paper concerns the underwater environment, and its effects on propagated signals. A synthetic propagation model, which uses parabolic equations, is briefly described. The model requires water surface, water column and lakebed information to predict a signal propagating through such an environment. A trial, which took place in Loch Fyne, Scotland, has provided the environmental data needed to input into the model. The trial also allowed for signals to be transmitted through the measured water column and recorded. Comparisons between the experimental and model predicted signals are presented.
{"title":"Propagation of signals in the water column: measurements and modelling","authors":"D. Phelps, S. Dugelay","doi":"10.1109/OCEANS.2002.1192015","DOIUrl":"https://doi.org/10.1109/OCEANS.2002.1192015","url":null,"abstract":"This paper concerns the underwater environment, and its effects on propagated signals. A synthetic propagation model, which uses parabolic equations, is briefly described. The model requires water surface, water column and lakebed information to predict a signal propagating through such an environment. A trial, which took place in Loch Fyne, Scotland, has provided the environmental data needed to input into the model. The trial also allowed for signals to be transmitted through the measured water column and recorded. Comparisons between the experimental and model predicted signals are presented.","PeriodicalId":431594,"journal":{"name":"OCEANS '02 MTS/IEEE","volume":"91 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131658761","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 : 2002-10-29DOI: 10.1109/OCEANS.2002.1192117
H. Shyu, R. Hillson
In responding to concerns about the potential impact of active sonar systems on marine mammals, the US Navy has initiated a research and development program to study the effects of sound on the marine environment (EMSE). As part of the ESME effort, the Naval Research Laboratory is developing a workbench for integrating the diverse software modules under development by other ESME researchers. This workbench models the complete sound propagation path: from the source, through the medium, and to the biosensor system. It allows researchers to explore different scenarios for the interaction between sonar, the marine environment, and marine mammals. There are several issues in building such a workbench. First, the Temporary Threshold Shift (TTS) data for marine mammals are very limited. Both behavioral and physiological models for estimating the TTS for marine mammals as a function of auditory exposure are still in their early stages of development. Second, developing an ocean acoustic propagation model that can produce accurate sound field estimations in shallow water environments is still a challenge. Third, collecting accurate oceanographic data directly such as sound speed profiles, sea floor properties, and bathymetric data is very expensive. The accuracy of oceanographic data directly affects the outcome of an ocean acoustics propagation model. As more and more experimental data are collected, the TTS estimation models for marine mammal auditory systems and the ocean acoustic propagation models will both improve. Furthermore, the Navy has an ongoing effort to collect more accurate oceanographic data. To build a software system that can incorporate software components subject to modification, the components should be modular. Modular components may be easily replaced by improved components provided that the interfaces are clearly defined and stable. This paper describes the current state of this software workbench development effort and discusses the issues involved in integrating different software models developed independently for modeling different phenomena.
{"title":"Integrating ocean acoustic propagation models and marine mammal auditory models","authors":"H. Shyu, R. Hillson","doi":"10.1109/OCEANS.2002.1192117","DOIUrl":"https://doi.org/10.1109/OCEANS.2002.1192117","url":null,"abstract":"In responding to concerns about the potential impact of active sonar systems on marine mammals, the US Navy has initiated a research and development program to study the effects of sound on the marine environment (EMSE). As part of the ESME effort, the Naval Research Laboratory is developing a workbench for integrating the diverse software modules under development by other ESME researchers. This workbench models the complete sound propagation path: from the source, through the medium, and to the biosensor system. It allows researchers to explore different scenarios for the interaction between sonar, the marine environment, and marine mammals. There are several issues in building such a workbench. First, the Temporary Threshold Shift (TTS) data for marine mammals are very limited. Both behavioral and physiological models for estimating the TTS for marine mammals as a function of auditory exposure are still in their early stages of development. Second, developing an ocean acoustic propagation model that can produce accurate sound field estimations in shallow water environments is still a challenge. Third, collecting accurate oceanographic data directly such as sound speed profiles, sea floor properties, and bathymetric data is very expensive. The accuracy of oceanographic data directly affects the outcome of an ocean acoustics propagation model. As more and more experimental data are collected, the TTS estimation models for marine mammal auditory systems and the ocean acoustic propagation models will both improve. Furthermore, the Navy has an ongoing effort to collect more accurate oceanographic data. To build a software system that can incorporate software components subject to modification, the components should be modular. Modular components may be easily replaced by improved components provided that the interfaces are clearly defined and stable. This paper describes the current state of this software workbench development effort and discusses the issues involved in integrating different software models developed independently for modeling different phenomena.","PeriodicalId":431594,"journal":{"name":"OCEANS '02 MTS/IEEE","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115239852","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 : 2002-10-29DOI: 10.1109/OCEANS.2002.1191924
B. Rapids, G. Lauchle
In bistatic scattering geometries, the detection of a signal scattered in the forward direction by a stationary object can be difficult because the incident and scattered waves combine into a simultaneous mixture. Reverberation can complicate the measurements even further. At opposite ends of the forward scattering phenomenon are the Rayleigh scattering region, where the scattered wave is masked by the incident wave; and the geometrical optics region, where the two wavefields interfere to form an acoustic shadow. Pressure sensors can only provide an estimate of the magnitude of the intensity associated with an equivalent plane wave field, while true intensity sensors measure simultaneously the acoustic pressure and particle velocity components (or a related quantity such as acceleration, displacement, or pressure gradient) at a single "point" in space. The coherent measurement of both acoustic field parameters provides not only the magnitude of acoustic intensity but the phase between acoustic pressure and velocity. It is hypothesized that processing methods could be developed which exploit the relationship between these types of coherent measurements in order to extract information regarding the presence and nature of an object residing on or very close to the bistatic baseline. In this paper, this hypothesis is explored computationally using a rigid prolate spheroid as a canonical scattering body.
{"title":"Processing of forward scattered acoustic fields with intensity sensors","authors":"B. Rapids, G. Lauchle","doi":"10.1109/OCEANS.2002.1191924","DOIUrl":"https://doi.org/10.1109/OCEANS.2002.1191924","url":null,"abstract":"In bistatic scattering geometries, the detection of a signal scattered in the forward direction by a stationary object can be difficult because the incident and scattered waves combine into a simultaneous mixture. Reverberation can complicate the measurements even further. At opposite ends of the forward scattering phenomenon are the Rayleigh scattering region, where the scattered wave is masked by the incident wave; and the geometrical optics region, where the two wavefields interfere to form an acoustic shadow. Pressure sensors can only provide an estimate of the magnitude of the intensity associated with an equivalent plane wave field, while true intensity sensors measure simultaneously the acoustic pressure and particle velocity components (or a related quantity such as acceleration, displacement, or pressure gradient) at a single \"point\" in space. The coherent measurement of both acoustic field parameters provides not only the magnitude of acoustic intensity but the phase between acoustic pressure and velocity. It is hypothesized that processing methods could be developed which exploit the relationship between these types of coherent measurements in order to extract information regarding the presence and nature of an object residing on or very close to the bistatic baseline. In this paper, this hypothesis is explored computationally using a rigid prolate spheroid as a canonical scattering body.","PeriodicalId":431594,"journal":{"name":"OCEANS '02 MTS/IEEE","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115891204","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 : 2002-10-29DOI: 10.1109/OCEANS.2002.1191985
S. K. Mitchell, S. P. Pitt
Frequencies of experimental synthetic aperture sonars (SAS) have varied from relatively low, with the goal of detecting and imaging buried targets, to relatively high to provide high resolution images of proud targets and bottom structure. This paper describes circular SAS studies at ARL:UT using recently acquired, highly controlled data which allows processing with arbitrary sonar parameters against both proud and buried targets. The nature of the data supports circular SAS apertures up to 360 degrees, corresponding to reflection tomography. SAS algorithms have been applied with both proud and buried target data to produce images as a function of target aspect for selected sonar parameters. Examples indicate effects of choice of sonar parameters on imaging for discrimination, classification, and identification.
{"title":"SAS imaging of proud and buried targets at search frequencies","authors":"S. K. Mitchell, S. P. Pitt","doi":"10.1109/OCEANS.2002.1191985","DOIUrl":"https://doi.org/10.1109/OCEANS.2002.1191985","url":null,"abstract":"Frequencies of experimental synthetic aperture sonars (SAS) have varied from relatively low, with the goal of detecting and imaging buried targets, to relatively high to provide high resolution images of proud targets and bottom structure. This paper describes circular SAS studies at ARL:UT using recently acquired, highly controlled data which allows processing with arbitrary sonar parameters against both proud and buried targets. The nature of the data supports circular SAS apertures up to 360 degrees, corresponding to reflection tomography. SAS algorithms have been applied with both proud and buried target data to produce images as a function of target aspect for selected sonar parameters. Examples indicate effects of choice of sonar parameters on imaging for discrimination, classification, and identification.","PeriodicalId":431594,"journal":{"name":"OCEANS '02 MTS/IEEE","volume":"113 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124331695","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 : 2002-10-29DOI: 10.1109/OCEANS.2002.1192074
A. Blumberg, Q. Ahsan, Honghai Li, J. Blaha
An operational forecast modeling system for the Mississippi (MS) Sound/Bight has been developed. The system integrates a triple nested coastal ocean forecast modeling systems and a meteorological forecast model. The Mississippi Sound/Bight model based on ECOMSED, forms the central core of the operational forecast system. At its eastern and southern boundaries, the ECOMSED is coupled to a regional Gulf of Mexico (GOM) model in a manner that ensures seamless energy transfer between the two models. Meteorological forcing is provided by the Coupled Ocean/Atmospheric Mesoscale Prediction System, COAMPS. The forecast system automatically retrieves all available real-time river discharge data along the Gulf coast to be imposed as coastal boundary conditions. The operational MS Sound/Bight forecast model produces two 12-hour hindcast and two 48-hour forecasts everyday at 0000 and 1200 hours. The system is scheduled to run for 12 hours in a hindcast mode and then 48 hours in a forecast mode. However, these simulation periods can vary. Depending on the availability and lengths of inputs from the coupled GOM and COAMPS models, the operational system automatically sets the periods for hindcast and forecast simulations. The model saves the proper hydrodynamic information for a restart so that a smooth and seamless execution is possible to start the next cycle. All of the simulations of the model are performed and archived on the Major Shared Resource Center (MSRC) high-performance computers resident at NAVOCEANO, Stennis Space Center, MS. The archived model output includes hourly three-dimensional fields of salinity, temperature and currents and water level across the model domain. Quality control is performed before the results go to a post-processing phase. A post-processing routine, which runs autonomously, generates surface current, temperature and salinity distributions after the completion of each cycle of forecast. The model results are available on the NGLI website (www.navo.navy.mil/NGLI) for public use.
{"title":"An operational forecast modeling system for the Mississippi Sound/Bight","authors":"A. Blumberg, Q. Ahsan, Honghai Li, J. Blaha","doi":"10.1109/OCEANS.2002.1192074","DOIUrl":"https://doi.org/10.1109/OCEANS.2002.1192074","url":null,"abstract":"An operational forecast modeling system for the Mississippi (MS) Sound/Bight has been developed. The system integrates a triple nested coastal ocean forecast modeling systems and a meteorological forecast model. The Mississippi Sound/Bight model based on ECOMSED, forms the central core of the operational forecast system. At its eastern and southern boundaries, the ECOMSED is coupled to a regional Gulf of Mexico (GOM) model in a manner that ensures seamless energy transfer between the two models. Meteorological forcing is provided by the Coupled Ocean/Atmospheric Mesoscale Prediction System, COAMPS. The forecast system automatically retrieves all available real-time river discharge data along the Gulf coast to be imposed as coastal boundary conditions. The operational MS Sound/Bight forecast model produces two 12-hour hindcast and two 48-hour forecasts everyday at 0000 and 1200 hours. The system is scheduled to run for 12 hours in a hindcast mode and then 48 hours in a forecast mode. However, these simulation periods can vary. Depending on the availability and lengths of inputs from the coupled GOM and COAMPS models, the operational system automatically sets the periods for hindcast and forecast simulations. The model saves the proper hydrodynamic information for a restart so that a smooth and seamless execution is possible to start the next cycle. All of the simulations of the model are performed and archived on the Major Shared Resource Center (MSRC) high-performance computers resident at NAVOCEANO, Stennis Space Center, MS. The archived model output includes hourly three-dimensional fields of salinity, temperature and currents and water level across the model domain. Quality control is performed before the results go to a post-processing phase. A post-processing routine, which runs autonomously, generates surface current, temperature and salinity distributions after the completion of each cycle of forecast. The model results are available on the NGLI website (www.navo.navy.mil/NGLI) for public use.","PeriodicalId":431594,"journal":{"name":"OCEANS '02 MTS/IEEE","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115092550","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 : 2002-10-29DOI: 10.1109/OCEANS.2002.1192009
J. Trubuil, G. Lapierre, T. Le Gall, J. Labat
There is no doubt about the growing interest for the underwater acoustic communications. Among all existing applications, the objective of the Groupe d'Etudes Sous-Marines de l'Atlantique (GESMA) is to develop a sufficiently robust high data rate acoustic link, named TRIDENT. For that purpose, different kinds of information (texts, images...) could be periodically transmitted through the acoustic channel. A realtime receiver, based on the spatio-temporal blind adaptive decision feedback equalizer, developed and patented by ENST Bretagne [J. Labet et al., 1995], was designed to cope with all perturbations induced by such harsh channels. Some sea trials have been carried out in June 2002. The first results are clearly convincing since most of the 48 sequences of 5 minutes are successfully detected by the DSP-based real-time receiver. This acoustic system allows transmission at data rates ranging from 8 to 25 kbps in horizontal configuration.
毫无疑问，人们对水声通信的兴趣日益浓厚。在所有现有的应用中，大西洋海军陆战队研究小组(GESMA)的目标是开发一个足够强大的高数据速率声学链路，名为TRIDENT。为此，不同种类的信息(文本、图像……)可以通过声道周期性地传输。基于时空盲自适应决策反馈均衡器的实时接收机，由ENST Bretagne开发并获得专利[J]。Labet et al.， 1995]的设计是为了应对由这种恶劣通道引起的所有扰动。在2002年6月进行了一些海试。由于基于dsp的实时接收器成功检测了48个5分钟序列中的大多数序列，因此第一个结果显然具有说服力。该声学系统允许在水平配置下以8到25kbps的数据速率传输数据。
{"title":"Real-time high data rate acoustic link based on spatio-temporal blind equalization: the TRIDENT acoustic system","authors":"J. Trubuil, G. Lapierre, T. Le Gall, J. Labat","doi":"10.1109/OCEANS.2002.1192009","DOIUrl":"https://doi.org/10.1109/OCEANS.2002.1192009","url":null,"abstract":"There is no doubt about the growing interest for the underwater acoustic communications. Among all existing applications, the objective of the Groupe d'Etudes Sous-Marines de l'Atlantique (GESMA) is to develop a sufficiently robust high data rate acoustic link, named TRIDENT. For that purpose, different kinds of information (texts, images...) could be periodically transmitted through the acoustic channel. A realtime receiver, based on the spatio-temporal blind adaptive decision feedback equalizer, developed and patented by ENST Bretagne [J. Labet et al., 1995], was designed to cope with all perturbations induced by such harsh channels. Some sea trials have been carried out in June 2002. The first results are clearly convincing since most of the 48 sequences of 5 minutes are successfully detected by the DSP-based real-time receiver. This acoustic system allows transmission at data rates ranging from 8 to 25 kbps in horizontal configuration.","PeriodicalId":431594,"journal":{"name":"OCEANS '02 MTS/IEEE","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117305858","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 : 2002-10-29DOI: 10.1109/OCEANS.2002.1193297
H. T. Vosbein
Detailed computer modeling has conclusively shown that out-of-plane scattering and small-scale bathymetric roughness influence the backscattered acoustic intensity in nontrivial ways for acoustically hard surfaces such as sand, gravel, shells and rock. This paper presents a preliminary technique for including these effects statistically in sonar performance modeling by adjusting the sea floor material parameter presently used in sonar models to account for them.
{"title":"Towards better sonar performance predictions","authors":"H. T. Vosbein","doi":"10.1109/OCEANS.2002.1193297","DOIUrl":"https://doi.org/10.1109/OCEANS.2002.1193297","url":null,"abstract":"Detailed computer modeling has conclusively shown that out-of-plane scattering and small-scale bathymetric roughness influence the backscattered acoustic intensity in nontrivial ways for acoustically hard surfaces such as sand, gravel, shells and rock. This paper presents a preliminary technique for including these effects statistically in sonar performance modeling by adjusting the sea floor material parameter presently used in sonar models to account for them.","PeriodicalId":431594,"journal":{"name":"OCEANS '02 MTS/IEEE","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116027216","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 : 2002-10-29DOI: 10.1109/OCEANS.2002.1191899
J. P. McKinney, G. Howell
This paper examines the coherence between kinematic variables from different types of bottom mounted instruments used for coastal directional wave measurements. Long term field data from PPP, PEMCM and PADV for several locations and wave conditions are analyzed for wave direction and coherence. Directional wave measurements analyzed from arrays of sensors assume that the time series of wave kinematics are statistically homogenous. Sensor time series should differ only in amplitude and phase. For real-world field measurements sensor data contains noise components and systematic errors and biases. Coherence between sensor pairs is a common method of quantifying the noise and error. Our results show very high coherence between individual pressure time series in short base-line pressure arrays. Slope components computed from the pressure array are used for directional analysis. We find slope coherence less than the scalar pressures but generally high. Coherence between U and V components of horizontal velocity measured by current meters should be very high because they are Cartesian components of the current vector. Our data show this is generally true for common E-M current meters. For acoustic Doppler (PADV) velocity meters the coherence was significantly lower. Coherence is potentially useful as a metric for comparing different sensor systems accuracy for directional estimates. It also is frequently used as a quality control test for automated data analysis. Non-acoustic systems generally exhibit high coherence when operating correctly. For acoustic systems, the question arises as how good must coherence be for acceptable data. We present exploratory analyses that examine then relationship between coherence and the quality of directional estimates.
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