Pub Date : 2014-09-01DOI: 10.1109/OCEANS.2014.7003235
A. Dzvonkovskaya, C. Merz, Yonggang Liu, R. Weisberg, T. Helzel, L. Petersen
High-frequency (HF) radar systems located at the coast are well-known as a measurement tool for synoptic online mapping of ocean surface current fields. These radars use surface electromagnetic wave propagation coupled to the salty ocean surface and are capable of monitoring thousands of square kilometers of the ocean surface. For oceanographic applications, low transmit power HF radar beamforming systems have been developed for operation in the 3-30 MHz frequency band. These systems require the use of a linear array of receive antenna elements whose inter-element spacing is dependent upon the operational frequency chosen. This paper presents a new approach of applying the Multiple Input Multiple Output (MIMO) technique with a synthesized antenna aperture to a compact HF ocean radar. The initial results show that the MIMO HF radar configuration with collocated receive antennas can be used for both oceanographic measurements and ship tracking applications. Initial MIMO results also reveal that positive results can be achieved from a reduced length receive array without reducing overall system performance. The comparison between standard and MIMO configurations has been focused on the estimation of surface current velocities and comparison with in-situ acoustic Doppler current profiler (ADCP) measurements.
{"title":"Initial surface current measurements on the West Florida shelf using WERA HF ocean radar with multiple input multiple output (MIMO) synthetic aperture","authors":"A. Dzvonkovskaya, C. Merz, Yonggang Liu, R. Weisberg, T. Helzel, L. Petersen","doi":"10.1109/OCEANS.2014.7003235","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003235","url":null,"abstract":"High-frequency (HF) radar systems located at the coast are well-known as a measurement tool for synoptic online mapping of ocean surface current fields. These radars use surface electromagnetic wave propagation coupled to the salty ocean surface and are capable of monitoring thousands of square kilometers of the ocean surface. For oceanographic applications, low transmit power HF radar beamforming systems have been developed for operation in the 3-30 MHz frequency band. These systems require the use of a linear array of receive antenna elements whose inter-element spacing is dependent upon the operational frequency chosen. This paper presents a new approach of applying the Multiple Input Multiple Output (MIMO) technique with a synthesized antenna aperture to a compact HF ocean radar. The initial results show that the MIMO HF radar configuration with collocated receive antennas can be used for both oceanographic measurements and ship tracking applications. Initial MIMO results also reveal that positive results can be achieved from a reduced length receive array without reducing overall system performance. The comparison between standard and MIMO configurations has been focused on the estimation of surface current velocities and comparison with in-situ acoustic Doppler current profiler (ADCP) measurements.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"39 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":"126615329","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.2014.7003049
Samareh Attarsharghi, V. Mašek
In the North Atlantic Ocean accurate prediction of the trajectory of icebergs would enable optimization of shipping routes and offshore production processes. In this paper, we investigate the practical aspects of the proposed current measurement technique which is based on transit time method and cross correlation signal processing in a flow tank. The experiments are carried out as a prototype of a larger network of acoustic transducers to investigate the feasibility and/or limitations of this system for measuring the average-shallow depth current in the ocean.
{"title":"Ocean current monitoring via cross-correlation technique and node synchronisation","authors":"Samareh Attarsharghi, V. Mašek","doi":"10.1109/OCEANS.2014.7003049","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003049","url":null,"abstract":"In the North Atlantic Ocean accurate prediction of the trajectory of icebergs would enable optimization of shipping routes and offshore production processes. In this paper, we investigate the practical aspects of the proposed current measurement technique which is based on transit time method and cross correlation signal processing in a flow tank. The experiments are carried out as a prototype of a larger network of acoustic transducers to investigate the feasibility and/or limitations of this system for measuring the average-shallow depth current in the ocean.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"16 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":"126945487","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.2014.7003196
Sara Pensieri, R. Bozzano, M. Schiano, Laura Pensieri, F. Traverso, A. Trucco, P. Picco, A. Bordone
Underwater acoustic measurements have been recently carried out in Tethys Bay (Ross Sea, Antarctica) during the XXIX Italian Antarctic Expedition to support acoustic propagation studies in the area and to investigate the environmental noise. Tethys Bay is a small deep cove close to the Antarctic Italian base Mario Zucchelli Station (Baia Terra Nova -74°42' S e 164°07' E) and covered with sea-ice for most of the year. During the period of the experiment (November 2013) the pack-ice had an almost constant thickness of about 2.2 m, so that the measurements were performed deploying the instruments into the sea from holes drilled through the pack ice. The holes were located along the bay axis at a distance of about 500 m each other. The sea depth was around 200 m except for the hole close to the coast, where the sea depth was only 25 m. An hydrophone RESON TC 4032 was located in the outermost hole, while the acoustic source, a transceiver transmitting FSK pulses at 11 kHz, was placed in sequence in the other three holes. Every time, the measurements were performed at 0, 20 and 45 m depth for each configuration. Furthermore during the experiment, sea temperature, salinity and currents, as well as the main meteorological parameters were continuously measured. The analysis here reported mainly focuses on the acquired acoustic passive data. The passive measurements evidenced that the signal was generally dominated by different sounds from seals, which was prevailing on the noise due to human activities.
在第29届意大利南极考察期间，最近在特提斯湾(南极洲罗斯海)进行了水声测量，以支持该地区的声传播研究并调查环境噪声。特提斯湾是一个小深海湾，靠近意大利南极基地Mario Zucchelli站(Baia Terra Nova -74°42' S e 164°07' e)，一年中的大部分时间都被海冰覆盖。在实验期间(2013年11月)，浮冰的厚度几乎不变，约为2.2米，因此测量是通过在浮冰上钻的洞将仪器部署到海里进行的。这些孔沿海湾轴线分布，彼此相距约500米。除了靠近海岸的洞外，海水深度在200米左右，只有25米。水听器RESON TC 4032位于最外面的孔中，而声源，一个发送11 kHz FSK脉冲的收发器，依次放置在其他三个孔中。每次，对每种配置分别在0、20和45米深度进行测量。实验期间，连续测量了海温、盐度、海流及主要气象参数。本文的分析主要集中在采集的声被动数据上。被动测量表明，信号通常由来自海豹的不同声音主导，而人类活动引起的噪音占主导地位。
{"title":"Environmental acoustic noise observations in Tethys Bay (Terra Nova Bay, Ross Sea, Antarctica)","authors":"Sara Pensieri, R. Bozzano, M. Schiano, Laura Pensieri, F. Traverso, A. Trucco, P. Picco, A. Bordone","doi":"10.1109/OCEANS.2014.7003196","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003196","url":null,"abstract":"Underwater acoustic measurements have been recently carried out in Tethys Bay (Ross Sea, Antarctica) during the XXIX Italian Antarctic Expedition to support acoustic propagation studies in the area and to investigate the environmental noise. Tethys Bay is a small deep cove close to the Antarctic Italian base Mario Zucchelli Station (Baia Terra Nova -74°42' S e 164°07' E) and covered with sea-ice for most of the year. During the period of the experiment (November 2013) the pack-ice had an almost constant thickness of about 2.2 m, so that the measurements were performed deploying the instruments into the sea from holes drilled through the pack ice. The holes were located along the bay axis at a distance of about 500 m each other. The sea depth was around 200 m except for the hole close to the coast, where the sea depth was only 25 m. An hydrophone RESON TC 4032 was located in the outermost hole, while the acoustic source, a transceiver transmitting FSK pulses at 11 kHz, was placed in sequence in the other three holes. Every time, the measurements were performed at 0, 20 and 45 m depth for each configuration. Furthermore during the experiment, sea temperature, salinity and currents, as well as the main meteorological parameters were continuously measured. The analysis here reported mainly focuses on the acquired acoustic passive data. The passive measurements evidenced that the signal was generally dominated by different sounds from seals, which was prevailing on the noise due to human activities.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"49 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":"127580010","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.2014.7003120
Yuzhi Zhang, Yi Huang, L. Wan, Hao Zhou, Shengli Zhou, Xiaohong Shen, Haiyan Wang
Multiuser communication has been an important research area of underwater acoustic communications and networking. This paper studies the use of adaptive OFDMA in a multiuser downlink scenario, where a central node sends data to multiple distributed nodes simultaneously. The reduction of channel feedback via clustering and quantization is considered, and an interleaved power-bit loading algorithm is presented to jointly assign the data subcarriers to different users and allocate the power and bits on each subcarrier. Simulation results show the performance improvement due to subcarrier allocation with and without additional power and bit loading. An experiment conducted in a swimming pool illustrates potential benefits and challenges of harvesting the multiuser diversity through adaptive subcarrier allocation.
{"title":"Adaptive OFDMA for downlink underwater acoustic communications","authors":"Yuzhi Zhang, Yi Huang, L. Wan, Hao Zhou, Shengli Zhou, Xiaohong Shen, Haiyan Wang","doi":"10.1109/OCEANS.2014.7003120","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003120","url":null,"abstract":"Multiuser communication has been an important research area of underwater acoustic communications and networking. This paper studies the use of adaptive OFDMA in a multiuser downlink scenario, where a central node sends data to multiple distributed nodes simultaneously. The reduction of channel feedback via clustering and quantization is considered, and an interleaved power-bit loading algorithm is presented to jointly assign the data subcarriers to different users and allocate the power and bits on each subcarrier. Simulation results show the performance improvement due to subcarrier allocation with and without additional power and bit loading. An experiment conducted in a swimming pool illustrates potential benefits and challenges of harvesting the multiuser diversity through adaptive subcarrier allocation.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"16 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":"131294577","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.2014.7003023
A. Gunes, M. B. Guldogan, A. Bereketli
Underwater acoustic vector sensors (AVS) are devices which can measure scalar pressure and three dimensional acceleration or particle velocity with only one sensor. Direction of an acoustic target can be estimated by these four measured scalar values. Techniques based on either closed-form expressions or beamforming can be carried out for direction finding by using the axial projections of the gradient vector of the pressure from the target. In this work, the performances of direction of arrival (DOA) estimation techniques for a single underwater AVS are analyzed in detail under the effects of various error sources such as imperfect projections and ambient noise.
{"title":"A comparative study on the performances of the DF techniques using a single acoustic vector sensor","authors":"A. Gunes, M. B. Guldogan, A. Bereketli","doi":"10.1109/OCEANS.2014.7003023","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003023","url":null,"abstract":"Underwater acoustic vector sensors (AVS) are devices which can measure scalar pressure and three dimensional acceleration or particle velocity with only one sensor. Direction of an acoustic target can be estimated by these four measured scalar values. Techniques based on either closed-form expressions or beamforming can be carried out for direction finding by using the axial projections of the gradient vector of the pressure from the target. In this work, the performances of direction of arrival (DOA) estimation techniques for a single underwater AVS are analyzed in detail under the effects of various error sources such as imperfect projections and ambient noise.","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":"122501948","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.2014.7003093
A. Turetta, G. Casalino, E. Simetti, Alessandro Sperindé, Sandro Torelli
The use of Long Baseline (LBL) systems for localizing underwater vehicles is quite consolidated, as they guarantee a good nominal accuracy, not dependent on the operative depth and almost constant at any point inside the area delimited by the transponders. However the real achievable accuracy can be affected by different factors, mainly related with the knowledge of some environmental parameters (like the speed of sound), the quality of the employed instrumentations, and the level of calibration of the system, after its deployment in water. The paper specifically addresses the accuracy of a LBL-based localization procedure and presents the results of an error budget analysis. For each considered error source, a closed form of the induced localization error is derived and discussed with the intent of enabling the characterization of the real obtainable accuracy within a typical application. The overall study is finally supported and validated by a detailed set of simulative results.
{"title":"Analysis of the accuracy of a LBL-based underwater localization procedure","authors":"A. Turetta, G. Casalino, E. Simetti, Alessandro Sperindé, Sandro Torelli","doi":"10.1109/OCEANS.2014.7003093","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003093","url":null,"abstract":"The use of Long Baseline (LBL) systems for localizing underwater vehicles is quite consolidated, as they guarantee a good nominal accuracy, not dependent on the operative depth and almost constant at any point inside the area delimited by the transponders. However the real achievable accuracy can be affected by different factors, mainly related with the knowledge of some environmental parameters (like the speed of sound), the quality of the employed instrumentations, and the level of calibration of the system, after its deployment in water. The paper specifically addresses the accuracy of a LBL-based localization procedure and presents the results of an error budget analysis. For each considered error source, a closed form of the induced localization error is derived and discussed with the intent of enabling the characterization of the real obtainable accuracy within a typical application. The overall study is finally supported and validated by a detailed set of simulative results.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"335 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":"122510730","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.2014.7003030
Laura J. Johnson, R. Green, M. Leeson
Underwater optical wireless has two distinct modes of communication depending on the choice of transmitter technology; short-ranged dispersive LED links (<;20m) and longdistance, narrow laser links. In both cases, existing propagation models use a single-value estimation of attenuation but this is not accurate for the latter. Changes in attenuation are caused by variable composition where the natural Gaussian profile of chlorophyll concentration with depth is the biggest contributing factor. With this in mind, this research looks at how varying the orientation of communication affects the average transmission for longer ranged underwater optical links. This is repeated for areas with low, medium and high levels of surface turbidity at 50m depth increments. Highest attenuation in found in links which have the largest portion transmitted through a chlorophyll peak, this occurs between 15-45° for both high and mid turbidity levels which correspond to the peaks below 0m and 50m respectively. This study also calculates how seawater refractive index gradients with depth alter the beam direction for different optical wireless links at angles to the vertical. It is found that angles closer to the vertical undergo higher displacements from their receivers as the gradient over which they are communicating is greater.
{"title":"The impact of link orientation in underwater optical wireless communication systems","authors":"Laura J. Johnson, R. Green, M. Leeson","doi":"10.1109/OCEANS.2014.7003030","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003030","url":null,"abstract":"Underwater optical wireless has two distinct modes of communication depending on the choice of transmitter technology; short-ranged dispersive LED links (<;20m) and longdistance, narrow laser links. In both cases, existing propagation models use a single-value estimation of attenuation but this is not accurate for the latter. Changes in attenuation are caused by variable composition where the natural Gaussian profile of chlorophyll concentration with depth is the biggest contributing factor. With this in mind, this research looks at how varying the orientation of communication affects the average transmission for longer ranged underwater optical links. This is repeated for areas with low, medium and high levels of surface turbidity at 50m depth increments. Highest attenuation in found in links which have the largest portion transmitted through a chlorophyll peak, this occurs between 15-45° for both high and mid turbidity levels which correspond to the peaks below 0m and 50m respectively. This study also calculates how seawater refractive index gradients with depth alter the beam direction for different optical wireless links at angles to the vertical. It is found that angles closer to the vertical undergo higher displacements from their receivers as the gradient over which they are communicating is greater.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"22 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":"124013649","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.2014.7003058
Anthony H. Sylvester, J. Delmerico, A. Trimble, B. Bingham
Two feedback controllers are presented that utilize data averaging and model-based estimation to offset the effects of sensor noise and achieve precise control of an autonomous underwater vehicle (AUV) variable buoyancy system (VBS). Operation of the bottom skimming AUV requires a constant reaction force between the seabed and the vehicle. While performing a mission, variable seafloor topography and a changing payload weight requires the use of a VBS to maintain the reaction force. Two traits of the VBS system that make this a challenging problem are the presence of sensor noise and fast on/off actuation relative to the sensor update rate. It was discovered that both controllers function under these conditions but the model-based controller provides more precise control of the system. This paper presents a comparison between these two control algorithms based on both simulation results and field experiments in a coastal environment.
{"title":"Variable buoyancy control for a bottom skimming autonomous underwater vehicle","authors":"Anthony H. Sylvester, J. Delmerico, A. Trimble, B. Bingham","doi":"10.1109/OCEANS.2014.7003058","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003058","url":null,"abstract":"Two feedback controllers are presented that utilize data averaging and model-based estimation to offset the effects of sensor noise and achieve precise control of an autonomous underwater vehicle (AUV) variable buoyancy system (VBS). Operation of the bottom skimming AUV requires a constant reaction force between the seabed and the vehicle. While performing a mission, variable seafloor topography and a changing payload weight requires the use of a VBS to maintain the reaction force. Two traits of the VBS system that make this a challenging problem are the presence of sensor noise and fast on/off actuation relative to the sensor update rate. It was discovered that both controllers function under these conditions but the model-based controller provides more precise control of the system. This paper presents a comparison between these two control algorithms based on both simulation results and field experiments in a coastal environment.","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":"127907120","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.2014.7003157
Ying Zhang, Jiamin Huang, Hangfang Zhao, Wen Xu
Acoustic mapping of ocean currents with Distributed Networked Underwater Sensors (DNUS) system is an effective and energy-saving technique for monitoring oceanographic environments. Unlike the common acoustic tomography methods, this new approach can locally reconstruct ocean currents using data between neighboring sensors. Considering that ocean currents are highly correlated during a short time interval, this paper develops a Kalman filter based tracking approach to improve the DNUS-based ocean current estimation. A 2-D ocean model is used to generate synthetic observational data. The simulation results show that, with the information of the previous ocean current estimates introduced, the proposed method can outperform the traditional current mapping method with DNUS-type system.
{"title":"Kalman tracking of ocean current field based on distributed sensor network","authors":"Ying Zhang, Jiamin Huang, Hangfang Zhao, Wen Xu","doi":"10.1109/OCEANS.2014.7003157","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003157","url":null,"abstract":"Acoustic mapping of ocean currents with Distributed Networked Underwater Sensors (DNUS) system is an effective and energy-saving technique for monitoring oceanographic environments. Unlike the common acoustic tomography methods, this new approach can locally reconstruct ocean currents using data between neighboring sensors. Considering that ocean currents are highly correlated during a short time interval, this paper develops a Kalman filter based tracking approach to improve the DNUS-based ocean current estimation. A 2-D ocean model is used to generate synthetic observational data. The simulation results show that, with the information of the previous ocean current estimates introduced, the proposed method can outperform the traditional current mapping method with DNUS-type system.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"39 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":"129150631","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.2014.7003159
Al-Abbass Y. Al-Habashneh, C. Moloney, E. Gill
Scan conversion, as a re-sampling process, is expected to add non-wave components to the wave spectrum. Resampling processes involve applying a low-pass filter to retrieve the original image followed by sampling on the new Cartesian grid. Scan conversion is necessary for ocean wave spectrum estimation using the Cartesian Fourier Transform (CFT). The Polar Fourier Transform (PFT) was originally proposed to avoid this intermediate stage and apply the transformation directly on the radar native form. In this paper, which incorporates field data, the PFT performance in estimating the wave spectrum is tested and compared to results from the CFT. Results show that the PFT outperforms the CFT at lower threshold values. This may imply that part of the noise added to the spectrum is due to the scan conversion process.
{"title":"Performance of the Polar Fourier transform for ocean wave spectrum estimation from marine radar","authors":"Al-Abbass Y. Al-Habashneh, C. Moloney, E. Gill","doi":"10.1109/OCEANS.2014.7003159","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003159","url":null,"abstract":"Scan conversion, as a re-sampling process, is expected to add non-wave components to the wave spectrum. Resampling processes involve applying a low-pass filter to retrieve the original image followed by sampling on the new Cartesian grid. Scan conversion is necessary for ocean wave spectrum estimation using the Cartesian Fourier Transform (CFT). The Polar Fourier Transform (PFT) was originally proposed to avoid this intermediate stage and apply the transformation directly on the radar native form. In this paper, which incorporates field data, the PFT performance in estimating the wave spectrum is tested and compared to results from the CFT. Results show that the PFT outperforms the CFT at lower threshold values. This may imply that part of the noise added to the spectrum is due to the scan conversion process.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"5 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":"128532466","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}
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