Pub Date : 2014-09-01DOI: 10.1109/OCEANS.2014.7003227
N. Cruz, J. Alves
Autonomous sailing robots are a relatively new technology for oceanographic missions, targeting at long term presence in the ocean by using wind as the main source of propulsion. This paper addresses the navigation performance of FASt, an autonomous sailboat being developed in Porto, Portugal, since 2008. A series of results selected from various sea trials illustrate the accuracy of navigation and the maneuvering ability. The paper provides some quantitative performance in downwind, sidewind and upwind trajectories, with various environmental conditions. It also addresses the ability to stay within a watch circle of a few tens of meters, during the station keeping maneuver.
{"title":"Navigation performance of an autonomous sailing robot","authors":"N. Cruz, J. Alves","doi":"10.1109/OCEANS.2014.7003227","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003227","url":null,"abstract":"Autonomous sailing robots are a relatively new technology for oceanographic missions, targeting at long term presence in the ocean by using wind as the main source of propulsion. This paper addresses the navigation performance of FASt, an autonomous sailboat being developed in Porto, Portugal, since 2008. A series of results selected from various sea trials illustrate the accuracy of navigation and the maneuvering ability. The paper provides some quantitative performance in downwind, sidewind and upwind trajectories, with various environmental conditions. It also addresses the ability to stay within a watch circle of a few tens of meters, during the station keeping maneuver.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127846231","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 : 2014-09-01DOI: 10.1109/OCEANS.2014.7003086
D. Illig, Luke Rumbaugh, W. Jemison, A. Laux, L. Mullen
A new backscatter suppression technique is applied to a wideband modulation scheme to enhance optical ranging in underwater environments. The statistical digital signal processing (DSP) approach of blind signal separation (BSS) [1-2] is applied to a frequency domain reflectometry (FDR) [3-4] ranging system. Applying BSS to the FDR system allows the backscatter return to be dynamically measured and cancelled out before computing range. Results from simulations and laboratory experiments are presented to demonstrate the combined FDR/BSS approach.
{"title":"Statistical backscatter suppression technique for a wideband hybrid lidar-radar ranging system","authors":"D. Illig, Luke Rumbaugh, W. Jemison, A. Laux, L. Mullen","doi":"10.1109/OCEANS.2014.7003086","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003086","url":null,"abstract":"A new backscatter suppression technique is applied to a wideband modulation scheme to enhance optical ranging in underwater environments. The statistical digital signal processing (DSP) approach of blind signal separation (BSS) [1-2] is applied to a frequency domain reflectometry (FDR) [3-4] ranging system. Applying BSS to the FDR system allows the backscatter return to be dynamically measured and cancelled out before computing range. Results from simulations and laboratory experiments are presented to demonstrate the combined FDR/BSS approach.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"42 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131277927","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 : 2014-09-01DOI: 10.1109/OCEANS.2014.7003284
E. Howlett, D. Snowden, R. Signell, K. Knee, Douglas Wilson
The US Integrated Ocean Observing System (IOOS®) is a collaboration between Federal, State, Local, Academic and Commercial partners to manage and/or provide access to a wide range of ocean observing assets and data feeds, including in-situ buoys, drifters, gliders, radar, satellite data, and numerical models and meet the needs of the ocean data community. This paper provides a discussion on the evolution of DMAC within IOOS, shows how the evolved DMAC will de-centralize ocean observing and enable the RAs to establish operational observing systems and create new forecast products supporting ocean, coastal, and estuarine interests and provides an update on the status of the current system.
{"title":"Data management update for the integrated ocean observing system (IOOS®)","authors":"E. Howlett, D. Snowden, R. Signell, K. Knee, Douglas Wilson","doi":"10.1109/OCEANS.2014.7003284","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003284","url":null,"abstract":"The US Integrated Ocean Observing System (IOOS®) is a collaboration between Federal, State, Local, Academic and Commercial partners to manage and/or provide access to a wide range of ocean observing assets and data feeds, including in-situ buoys, drifters, gliders, radar, satellite data, and numerical models and meet the needs of the ocean data community. This paper provides a discussion on the evolution of DMAC within IOOS, shows how the evolved DMAC will de-centralize ocean observing and enable the RAs to establish operational observing systems and create new forecast products supporting ocean, coastal, and estuarine interests and provides an update on the status of the current system.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131304405","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 : 2014-09-01DOI: 10.1109/OCEANS.2014.7003082
Junnan Song, Shalabh Gupta, J. Hare
This paper presents a game-theoretic method for cooperative coverage of a priori unknown environments using a team of autonomous vehicles. These autonomous vehicles are required to cooperatively scan the search area without human supervision as autonomous entities. However, due to the lack of a priori knowledge of the exact obstacle locations, the trajectories of autonomous vehicles cannot be computed offline and need to be adapted as the environment is discovered in situ. In this regard, the cooperative coverage method is based upon the concept of multi-resolution navigation that consists of local navigation and global navigation. The main advantages of this algorithm are: i) the local navigation enables real-time locally optimal decisions with a reduced computational complexity by avoiding unnecessary global computations, and ii) the global navigation offers a wider view of the area seeking for unexplored regions. This algorithm prevents the autonomous vehicles from getting trapped into local minima, which is commonly encountered in potential field based algorithms. The neighboring agents among the team of autonomous vehicles exchange the most up-to-date environment information for collaborations. Given sufficient operation time, the team of autonomous vehicles are capable of achieving complete coverage in their own regions. However, in order to further improve cleaning efficiency and reduce operation time, the vehicles that finish early should participate in assisting others that are in need of help. In this sense, a cooperative game is designed to be played among involved agents for optimal task reallocation. This paper considers the cooperative oil spill cleaning application; however the concepts can be applied to general class of coverage problems. The efficacy of the algorithm is validated using autonomous vehicles equipped with lasers in an obstacle-rich environment on the high-fidelity Player/Stage simulator.
{"title":"Game-theoretic cooperative coverage using autonomous vehicles","authors":"Junnan Song, Shalabh Gupta, J. Hare","doi":"10.1109/OCEANS.2014.7003082","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003082","url":null,"abstract":"This paper presents a game-theoretic method for cooperative coverage of a priori unknown environments using a team of autonomous vehicles. These autonomous vehicles are required to cooperatively scan the search area without human supervision as autonomous entities. However, due to the lack of a priori knowledge of the exact obstacle locations, the trajectories of autonomous vehicles cannot be computed offline and need to be adapted as the environment is discovered in situ. In this regard, the cooperative coverage method is based upon the concept of multi-resolution navigation that consists of local navigation and global navigation. The main advantages of this algorithm are: i) the local navigation enables real-time locally optimal decisions with a reduced computational complexity by avoiding unnecessary global computations, and ii) the global navigation offers a wider view of the area seeking for unexplored regions. This algorithm prevents the autonomous vehicles from getting trapped into local minima, which is commonly encountered in potential field based algorithms. The neighboring agents among the team of autonomous vehicles exchange the most up-to-date environment information for collaborations. Given sufficient operation time, the team of autonomous vehicles are capable of achieving complete coverage in their own regions. However, in order to further improve cleaning efficiency and reduce operation time, the vehicles that finish early should participate in assisting others that are in need of help. In this sense, a cooperative game is designed to be played among involved agents for optimal task reallocation. This paper considers the cooperative oil spill cleaning application; however the concepts can be applied to general class of coverage problems. The efficacy of the algorithm is validated using autonomous vehicles equipped with lasers in an obstacle-rich environment on the high-fidelity Player/Stage simulator.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115862574","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 : 2014-09-01DOI: 10.1109/OCEANS.2014.7003298
D. Sudom, G. Timco, A. Tivy
For safe and efficient operations in the iceberg-infested waters offshore eastern Canada, accurate information on icebergs is needed. Databases on iceberg sightings, shapes and management techniques have been developed in order to bring all relevant iceberg information into one repository. Iceberg sightings have been recorded offshore Newfoundland and Labrador since the 1600s. Sighting methods, locations, yearly variability and uncertainties are discussed. In more recent times, detailed 2D and 3D measurements have been made of iceberg geometries, which are useful for structural load calculations. Techniques to deflect iceberg drift from critical offshore locations have also evolved over the past 40 years. The various methods that have been used for iceberg management are discussed, as well as the factors that affect their success rates. Relationships between historical iceberg populations and sea ice can be used to forecast iceberg severity in future seasons; updated correlations have been made between sea ice coverage and iceberg severity.
{"title":"Iceberg sightings, shapes and management techniques for offshore Newfoundland and Labrador: Historical data and future applications","authors":"D. Sudom, G. Timco, A. Tivy","doi":"10.1109/OCEANS.2014.7003298","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003298","url":null,"abstract":"For safe and efficient operations in the iceberg-infested waters offshore eastern Canada, accurate information on icebergs is needed. Databases on iceberg sightings, shapes and management techniques have been developed in order to bring all relevant iceberg information into one repository. Iceberg sightings have been recorded offshore Newfoundland and Labrador since the 1600s. Sighting methods, locations, yearly variability and uncertainties are discussed. In more recent times, detailed 2D and 3D measurements have been made of iceberg geometries, which are useful for structural load calculations. Techniques to deflect iceberg drift from critical offshore locations have also evolved over the past 40 years. The various methods that have been used for iceberg management are discussed, as well as the factors that affect their success rates. Relationships between historical iceberg populations and sea ice can be used to forecast iceberg severity in future seasons; updated correlations have been made between sea ice coverage and iceberg severity.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117328091","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 : 2014-09-01DOI: 10.1109/OCEANS.2014.7003069
G. Ferri, A. Munafò, R. Goldhahn, K. LePage
We describe the implementation of a novel non-myopic, receding horizon strategy to control the movement of an AUV towing a line array acting as a receiver node in a multistatic network for littoral surveillance and Anti-Submarine Warfare (ASW). The algorithm computes the vehicle heading angles to minimize the expected target position estimation error of a tracking filter. Minimizing this error is typically of the utmost interest in target state estimation since it is one way of maintaining track. The optimization solves a resulting decision tree taking into consideration a planning future horizon. In this paper, we focus on how to solve the different challenges related to the implementation of this kind of computational intensive algorithms on vehicles operating in realistic ASW scenarios and characterized by limited computational power. Specifically, we describe the multistatic network used in COLLAB13 experiments, how we simplify the solution of the resulting decision tree and the implementation of the algorithm in CMRE's software system running on AUVs and based on MOOS-IvP middleware. We conclude reporting results from COLLAB13 which demonstrate the feasibility to use the proposed algorithm in realistic operations onboard AUVs and its effectiveness over conventional predefined tracklines.
{"title":"Results from COLLAB13 sea trial on tracking underwater targets with AUVs in bistatic sonar scenarios","authors":"G. Ferri, A. Munafò, R. Goldhahn, K. LePage","doi":"10.1109/OCEANS.2014.7003069","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003069","url":null,"abstract":"We describe the implementation of a novel non-myopic, receding horizon strategy to control the movement of an AUV towing a line array acting as a receiver node in a multistatic network for littoral surveillance and Anti-Submarine Warfare (ASW). The algorithm computes the vehicle heading angles to minimize the expected target position estimation error of a tracking filter. Minimizing this error is typically of the utmost interest in target state estimation since it is one way of maintaining track. The optimization solves a resulting decision tree taking into consideration a planning future horizon. In this paper, we focus on how to solve the different challenges related to the implementation of this kind of computational intensive algorithms on vehicles operating in realistic ASW scenarios and characterized by limited computational power. Specifically, we describe the multistatic network used in COLLAB13 experiments, how we simplify the solution of the resulting decision tree and the implementation of the algorithm in CMRE's software system running on AUVs and based on MOOS-IvP middleware. We conclude reporting results from COLLAB13 which demonstrate the feasibility to use the proposed algorithm in realistic operations onboard AUVs and its effectiveness over conventional predefined tracklines.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123516863","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 : 2014-09-01DOI: 10.1109/OCEANS.2014.7003147
R. Jenkyns, S. Perkins, B. Biffard, M. Jeffries, Martin Heesemann, C. Rosa
The Digital Infrastructure group at Ocean Networks Canada (ONC) is responsible for the development and maintenance of the organization's data management, archive and distribution. Data acquired from sensors on cabled ocean observatories off the coast of British Columbia and in the Arctic are made available via ONC's online interface to a multidisciplinary community of scientists, the public, government and non-governmental agencies. In order to better enable scientists, ONC has embarked upon an initiative to leverage the OPeNDAP-NetCDF-CF framework for interoperability that has been gaining momentum with the oceanographic and climate communities. Funded by Canada's Advanced Research and Innovation Network's (CANARIE) Research Platform Interface program, the Extending Possibilities by Leveraging OPeNDAP for Remotely Exchanging (ExPLORE) Complex Oceanographic Data project aims to be operational by the end of 2014. Together with the Open Geospatial Consortium (OGC) Sensor Web Enablement (SWE)-compliant web-services, this project will significantly extend ONC's interoperability commitment. This framework was chosen due to the maturing infrastructure for developers and end-users, increasing community support, and demand from end-users for webservices. In brief, OPeNDAP (Open source Project for a Network Data Access Protocol) includes software and a protocol for transporting data across the web. The NetCDF (Network Common Data Form) data format and associated software libraries are particularly suited to scientific data arrays. Since these files are machine-independent and self-describing, data access and sharing are streamlined. The CF (Climate and Forecast) metadata convention designed for NetCDF files specifies metadata attributes and standardizes variables (names and measurement units). Building upon existing web-services and tools, ONC will be publishing additional web-services for increased functionality such as dataset discovery, metadata browsing and data access. Training resources like documentation, sample scripts and tutorials will assist the community in adopting these tools. Initial implementation will support multi-dimensional data from instruments like Acoustic Doppler Current Profilers or mobile platforms like gliders and vertical profilers. System architecture, novel implementation aspects, customized extensions and usage will be highlighted during the presentation. It is expected that this approach will enhance the utility of ONC's extensive datasets for researchers, and facilitate interoperability with other oceanographic data providers. Researchers will benefit by being able to query ONC data from within their working environment (e.g., MATLAB, R, Python), merge ONC data with other sources more seamlessly, and share routines for processing and visualization with less effort. Data providers and portals that support these standards will be able to integrate ONC data and form collaborative partnerships.
{"title":"Extending possibilities by leveraging OPeNDAP for remotely exchanging complex oceanographic data","authors":"R. Jenkyns, S. Perkins, B. Biffard, M. Jeffries, Martin Heesemann, C. Rosa","doi":"10.1109/OCEANS.2014.7003147","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003147","url":null,"abstract":"The Digital Infrastructure group at Ocean Networks Canada (ONC) is responsible for the development and maintenance of the organization's data management, archive and distribution. Data acquired from sensors on cabled ocean observatories off the coast of British Columbia and in the Arctic are made available via ONC's online interface to a multidisciplinary community of scientists, the public, government and non-governmental agencies. In order to better enable scientists, ONC has embarked upon an initiative to leverage the OPeNDAP-NetCDF-CF framework for interoperability that has been gaining momentum with the oceanographic and climate communities. Funded by Canada's Advanced Research and Innovation Network's (CANARIE) Research Platform Interface program, the Extending Possibilities by Leveraging OPeNDAP for Remotely Exchanging (ExPLORE) Complex Oceanographic Data project aims to be operational by the end of 2014. Together with the Open Geospatial Consortium (OGC) Sensor Web Enablement (SWE)-compliant web-services, this project will significantly extend ONC's interoperability commitment. This framework was chosen due to the maturing infrastructure for developers and end-users, increasing community support, and demand from end-users for webservices. In brief, OPeNDAP (Open source Project for a Network Data Access Protocol) includes software and a protocol for transporting data across the web. The NetCDF (Network Common Data Form) data format and associated software libraries are particularly suited to scientific data arrays. Since these files are machine-independent and self-describing, data access and sharing are streamlined. The CF (Climate and Forecast) metadata convention designed for NetCDF files specifies metadata attributes and standardizes variables (names and measurement units). Building upon existing web-services and tools, ONC will be publishing additional web-services for increased functionality such as dataset discovery, metadata browsing and data access. Training resources like documentation, sample scripts and tutorials will assist the community in adopting these tools. Initial implementation will support multi-dimensional data from instruments like Acoustic Doppler Current Profilers or mobile platforms like gliders and vertical profilers. System architecture, novel implementation aspects, customized extensions and usage will be highlighted during the presentation. It is expected that this approach will enhance the utility of ONC's extensive datasets for researchers, and facilitate interoperability with other oceanographic data providers. Researchers will benefit by being able to query ONC data from within their working environment (e.g., MATLAB, R, Python), merge ONC data with other sources more seamlessly, and share routines for processing and visualization with less effort. Data providers and portals that support these standards will be able to integrate ONC data and form collaborative partnerships.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"614 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123948973","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 : 2014-09-01DOI: 10.1109/OCEANS.2014.7003293
A. Macneill, M. El-Hawary
This work deals with modeling underwater power cables based on the ubiquitous two-port network theory applied to the distributed parameter representation of transmission links leading to the so-called exact lumped parameter line model. It is found for single-core underwater power cables with copper armor that a nominal pi model is accurate for lengths up to 25 km, two cascaded nominal pi models are accurate for up to 50 km, and a modified cascaded nominal pi model is accurate up to 100km. For single-core underwater power cables with steel armor, a nominal pi model is accurate for lengths up to 10 km, two cascaded nominal pi models are accurate for up to 30 km, and a modified cascaded nominal pi model is accurate up to 40km. For three-core underwater power cables, a nominal pi model is accurate for lengths up to 40 km, two cascaded nominal pi models are accurate for up to 75 km, and a modified cascaded nominal pi model is accurate up to 125 km.
{"title":"Underwater power cable approximation models for offshore applications","authors":"A. Macneill, M. El-Hawary","doi":"10.1109/OCEANS.2014.7003293","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003293","url":null,"abstract":"This work deals with modeling underwater power cables based on the ubiquitous two-port network theory applied to the distributed parameter representation of transmission links leading to the so-called exact lumped parameter line model. It is found for single-core underwater power cables with copper armor that a nominal pi model is accurate for lengths up to 25 km, two cascaded nominal pi models are accurate for up to 50 km, and a modified cascaded nominal pi model is accurate up to 100km. For single-core underwater power cables with steel armor, a nominal pi model is accurate for lengths up to 10 km, two cascaded nominal pi models are accurate for up to 30 km, and a modified cascaded nominal pi model is accurate up to 40km. For three-core underwater power cables, a nominal pi model is accurate for lengths up to 40 km, two cascaded nominal pi models are accurate for up to 75 km, and a modified cascaded nominal pi model is accurate up to 125 km.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125768789","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 : 2014-09-01DOI: 10.1109/OCEANS.2014.7003163
Khalid El-Darymli, C. Moloney, E. Gill, Peter F. McGuire, D. Power
Motivated by the conventional resolution theory, phase content in single-channel synthetic aperture radar (SAR) imagery is often discarded. In this paper, the validity of this practice is studied from the perspective of complex-valued statistics. Hence, for the phase content to be irrelevant, the complex-valued random variable has to be second-order circular. A procedure to characterize circularity/noncircularity in single-channel SAR imagery is presented. Our analysis is applied to real-world SAR chips from Radarsat-2 and MSTAR. For the case of extended targets, the complex-valued SAR chip is found to be inherently noncircular. Further, the strength of noncircularity is observed to be resolution-dependent. Also, a proportional relationship between noncircularity and nonlinearity is noted. These findings warrant investigating the statistical significance of this phenomenon in relevant target recognition applications.
{"title":"On circularity/noncircularity in single-channel synthetic aperture radar imagery","authors":"Khalid El-Darymli, C. Moloney, E. Gill, Peter F. McGuire, D. Power","doi":"10.1109/OCEANS.2014.7003163","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003163","url":null,"abstract":"Motivated by the conventional resolution theory, phase content in single-channel synthetic aperture radar (SAR) imagery is often discarded. In this paper, the validity of this practice is studied from the perspective of complex-valued statistics. Hence, for the phase content to be irrelevant, the complex-valued random variable has to be second-order circular. A procedure to characterize circularity/noncircularity in single-channel SAR imagery is presented. Our analysis is applied to real-world SAR chips from Radarsat-2 and MSTAR. For the case of extended targets, the complex-valued SAR chip is found to be inherently noncircular. Further, the strength of noncircularity is observed to be resolution-dependent. Also, a proportional relationship between noncircularity and nonlinearity is noted. These findings warrant investigating the statistical significance of this phenomenon in relevant target recognition applications.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2014-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125984797","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 : 2014-09-01DOI: 10.1109/OCEANS.2014.7003292
Peter K. LeHardy, C. Moore
On 21 March 2014, Phoenix International Holdings, Inc. (Phoenix) was tasked by the U.S. Navy, through a multi-year Naval Sea Systems Command (NAVSEA) contract, to provide undersea search services in response to the disappearance of Malaysia Airlines Flight 370 (MH370). In support of this tasking, Phoenix deployed 9 personnel, the Navy's Towed Pinger Locator (TPL), and Phoenix's Bluefin 21 Autonomous Underwater Vehicle (AUV) - a system called Artemis - to Perth, Australia. The initial phase of the search operation took place from 04-14 April and involved using the TPL to listen for the saltwater activated Underwater Locator Beacon (ULB) “pingers” mounted to the plane's Flight Data Recorder and Cockpit Voice Recorder (the black boxes). Working aboard the Australian Defense Vessel (ADV) Ocean Shield roughly 1600 km North West of Perth, Phoenix personnel deployed the TPL to depths ranging from 3000-6000 meters while listening for the black box pingers. TPL operations revealed several acoustic indications and, while not the same frequency as MH370 black box pingers, these acoustic indications were identified by crash investigators as worthy of further investigation. On 15 April Phoenix was tasked to commence AUV search operations in the area of the TPL identified acoustic indications. Over the next month and a half Artemis collected side scan sonar imagery of the seafloor in search of MH370 wreckage. At the conclusion of 70 operational days the Phoenix AUV had successfully searched 860 square kilometers, covering the prescribed search area, with no sign of aircraft debris. This result has since led crash investigators to conclude that the acoustic indications heard by the TPL were not from MH370 black box pingers. While this initial search did not result in the location of MH370, the operation did provide an exceptional demonstration of AUV technology. Throughout the search the vehicle provided high quality geo-referenced data containing clear imagery of the sea floor while working at depths as great as 5005 meters (a Bluefin 21 record). The search also included a 27 hour and 9 minute dive (another Bluefin 21 record). Despite not finding the aircraft, the successful collection of high quality data at extreme depths in a remote and unfamiliar part of the world is a noteworthy accomplishment and indicative of the future uses of AUV technology.
2014年3月21日，凤凰国际控股有限公司(Phoenix International Holdings, Inc.)受美国海军委托，通过一份为期多年的海军海上系统司令部(NAVSEA)合同，为马来西亚航空公司370航班(MH370)的失踪提供海底搜索服务。为了支持这项任务，凤凰号向澳大利亚珀斯部署了9名人员、海军拖曳ping信号定位器(TPL)和凤凰号蓝鳍21自主水下航行器(AUV)——一种名为Artemis的系统。搜索行动的初始阶段从4月4日至14日进行，使用TPL监听安装在飞机飞行数据记录仪和驾驶舱语音记录仪(黑匣子)上的盐水激活水下定位信标(ULB)“ping”。在珀斯西北约1600公里处的澳大利亚国防船(ADV)海盾号上，凤凰号的工作人员将TPL部署到3000-6000米的深度，同时监听黑匣子的ping信号。TPL操作发现了几个声音迹象，虽然频率与MH370黑匣子的ping信号不同，但坠机调查人员认为这些声音迹象值得进一步调查。4月15日，凤凰号受令在TPL识别出的声学指示区域开始AUV搜索行动。在接下来的一个半月里，阿尔忒弥斯收集了海底侧扫声纳图像，以寻找MH370残骸。在70天的行动结束时，凤凰号水下航行器成功搜索了860平方公里，覆盖了规定的搜索区域，没有发现飞机残骸的迹象。这一结果导致坠机调查人员得出结论，TPL听到的声音指示不是来自MH370黑匣子的ping信号。虽然最初的搜索并没有找到MH370的位置，但这次行动确实展示了水下航行器技术的非凡应用。在整个搜索过程中，该车辆提供了高质量的地理参考数据，其中包括海底的清晰图像，同时工作深度可达5005米(蓝鳍21的记录)。搜索还包括27小时9分钟的潜水(另一个蓝鳍21记录)。尽管没有找到飞机，但在世界偏远和陌生地区的极端深度成功收集高质量数据是一项值得注意的成就，并表明了水下航行器技术的未来应用。
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