Pub Date : 2014-09-01DOI: 10.1109/OCEANS.2014.7003197
J. Dillon, V. Myers
Repeat-pass interferometry is an extension of Synthetic Aperture Sonar (SAS) that exploits the temporal characteristics of seafloor reverberation by coherently combining echoes from multiple passes of the sonar platform. In order to achieve pass-to-pass coherence, the spatial separation between passes must be less than a value known as the critical baseline, which depends on the sonar parameters and the range-dependent imaging geometry. The temporal separation between passes must also be less than the coherence time of the seabed, which is highly environmentally dependent and which defines the maximum time interval between passes. It is also necessary to coregister the complex seabed images to within a fraction of a pixel (usually on the order of several millimeters for the centimeter resolution SAS used in mine countermeasures). This imposes strict requirements on the navigation accuracy of the sonar platform that cannot be met using inertial or underwater positioning sensors alone. This paper presents a data-driven method for estimating the repeat-pass coherence map using local coregistration of the complex SAS images from each pass. The method can be applied to any SAS without requiring access to raw acoustic data or post-processing of data from a high grade inertial navigation system. Experimental results are presented for a repeat-pass survey using AquaPix, a wideband 300 kHz interferometric SAS, installed on an ISE Arctic Explorer AUV during recent sea trials with Defence Research and Development Canada.
重复通道干涉测量是合成孔径声纳(SAS)的扩展，通过相干组合声纳平台多次通道的回波来利用海底混响的时间特征。为了实现通道到通道的相干性，通道之间的空间间隔必须小于一个称为临界基线的值，该值取决于声纳参数和距离相关的成像几何形状。通道之间的时间间隔也必须小于海底的相干时间，后者高度依赖于环境，并确定了通道之间的最大时间间隔。还需要将复杂的海底图像共同配准到一个像素的几分之一(对于地雷对抗中使用的厘米分辨率SAS，通常在几毫米量级)。这对声纳平台的导航精度提出了严格的要求，这是单独使用惯性或水下定位传感器无法满足的。本文提出了一种数据驱动的方法，利用每一遍复杂SAS图像的局部共配估计重复通过相干图。该方法可以应用于任何SAS，而不需要访问原始声学数据或来自高等级惯性导航系统的数据后处理。在最近与加拿大国防研究与发展公司进行的海上试验中，使用AquaPix(一种宽带300 kHz干涉式SAS)进行了重复通道测量的实验结果。AquaPix安装在ISE Arctic Explorer AUV上。
{"title":"Coherence estimation for repeat-pass interferometry","authors":"J. Dillon, V. Myers","doi":"10.1109/OCEANS.2014.7003197","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003197","url":null,"abstract":"Repeat-pass interferometry is an extension of Synthetic Aperture Sonar (SAS) that exploits the temporal characteristics of seafloor reverberation by coherently combining echoes from multiple passes of the sonar platform. In order to achieve pass-to-pass coherence, the spatial separation between passes must be less than a value known as the critical baseline, which depends on the sonar parameters and the range-dependent imaging geometry. The temporal separation between passes must also be less than the coherence time of the seabed, which is highly environmentally dependent and which defines the maximum time interval between passes. It is also necessary to coregister the complex seabed images to within a fraction of a pixel (usually on the order of several millimeters for the centimeter resolution SAS used in mine countermeasures). This imposes strict requirements on the navigation accuracy of the sonar platform that cannot be met using inertial or underwater positioning sensors alone. This paper presents a data-driven method for estimating the repeat-pass coherence map using local coregistration of the complex SAS images from each pass. The method can be applied to any SAS without requiring access to raw acoustic data or post-processing of data from a high grade inertial navigation system. Experimental results are presented for a repeat-pass survey using AquaPix, a wideband 300 kHz interferometric SAS, installed on an ISE Arctic Explorer AUV during recent sea trials with Defence Research and Development Canada.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"126 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":"114409394","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.2014.7003084
T. Butkiewicz
High-resolution elevation and bathymetry data for coastal zones is extremely valuable to many researchers, however the cost of acquiring such data is prohibitively expensive for most research budgets, as it relies on specialized hardware. Mass produced off-the-shelf consumer cameras and sensors are becoming increasingly powerful, and can be affordable alternatives for collecting data. Microsoft's original Kinect sensor was repurposed to collect data for Earth sciences research, but its low depth resolution hindered its usefulness for creating accurate maps. In this paper, we evaluate Microsoft's next generation Kinect for Windows v2 sensor, which employs time-of-flight technology. Based on our results, the new sensor has great potential for use in coastal mapping and other Earth science applications where budget constraints preclude the use of traditional remote sensing data acquisition technologies.
{"title":"Low-cost coastal mapping using Kinect v2 time-of-flight cameras","authors":"T. Butkiewicz","doi":"10.1109/OCEANS.2014.7003084","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003084","url":null,"abstract":"High-resolution elevation and bathymetry data for coastal zones is extremely valuable to many researchers, however the cost of acquiring such data is prohibitively expensive for most research budgets, as it relies on specialized hardware. Mass produced off-the-shelf consumer cameras and sensors are becoming increasingly powerful, and can be affordable alternatives for collecting data. Microsoft's original Kinect sensor was repurposed to collect data for Earth sciences research, but its low depth resolution hindered its usefulness for creating accurate maps. In this paper, we evaluate Microsoft's next generation Kinect for Windows v2 sensor, which employs time-of-flight technology. Based on our results, the new sensor has great potential for use in coastal mapping and other Earth science applications where budget constraints preclude the use of traditional remote sensing data acquisition technologies.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"14 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":"116174423","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.2014.7003124
M. Crowley, O. Schofield, S. Glenn, F. Whoriskey
Gliderpalooza represented a grass-roots coordinated field demonstration of ocean observing technologies spanning the eastern seaboard of North America. The overarching goal was to coordinate disparate ocean research efforts, funded by disparate programs from a variety of agencies to demonstrate continental scale coordination of various ocean observing technologies to sample ecologically relevant scales. The coordinated data from satellites, HF-Radar surface currents [1], moorings, drifters and models was focused on and around the distributed deployment of Slocum gliders. The seven science and technical goals were to: 1) provide a unique data set the modelers can use for years to come (real-time & hindcast) 2) provide a standardized dataset over ecological scales and information on fish/mammal migrations 3) provide a 3-D snapshot of the MAB cold pool 4) provide an extensive distributed instrumented network through the peak period of fall storms, demonstrating a community "surge" capacity 5) provide one, of many demonstrations, of the potential U.S. national glider network 6) proof of data flow throughput to the Global Telecommunications System (GTS) via DMAC and 7) engage undergraduates in ocean observing efforts. During the summer and fall of 2014, the Gliderpalooza team will once again work together, but with several additions to the group, the geographical scope will cover Texas to Newfoundland. There will be more than 30 glider deployments that will be assimilated by seven numerical ocean models. Acquisition of this massive data set of water column profiles will permit evaluation of the accuracy of the models, especially in the coastal zone. Additionally, new online educational tools developed through the NSF's Ocean Observatory Initiative (OOI) will be used to by students in the undergraduate classroom to analyze, compare and contrast the glider data in real-time during the fall 2014 semester.
{"title":"Gliderpalooza 2013 to modelpalooza 2014: Joint U.S. & Canadian ocean glider operations supporting multidisciplinary scientific research and education","authors":"M. Crowley, O. Schofield, S. Glenn, F. Whoriskey","doi":"10.1109/OCEANS.2014.7003124","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003124","url":null,"abstract":"Gliderpalooza represented a grass-roots coordinated field demonstration of ocean observing technologies spanning the eastern seaboard of North America. The overarching goal was to coordinate disparate ocean research efforts, funded by disparate programs from a variety of agencies to demonstrate continental scale coordination of various ocean observing technologies to sample ecologically relevant scales. The coordinated data from satellites, HF-Radar surface currents [1], moorings, drifters and models was focused on and around the distributed deployment of Slocum gliders. The seven science and technical goals were to: 1) provide a unique data set the modelers can use for years to come (real-time & hindcast) 2) provide a standardized dataset over ecological scales and information on fish/mammal migrations 3) provide a 3-D snapshot of the MAB cold pool 4) provide an extensive distributed instrumented network through the peak period of fall storms, demonstrating a community \"surge\" capacity 5) provide one, of many demonstrations, of the potential U.S. national glider network 6) proof of data flow throughput to the Global Telecommunications System (GTS) via DMAC and 7) engage undergraduates in ocean observing efforts. During the summer and fall of 2014, the Gliderpalooza team will once again work together, but with several additions to the group, the geographical scope will cover Texas to Newfoundland. There will be more than 30 glider deployments that will be assimilated by seven numerical ocean models. Acquisition of this massive data set of water column profiles will permit evaluation of the accuracy of the models, especially in the coastal zone. Additionally, new online educational tools developed through the NSF's Ocean Observatory Initiative (OOI) will be used to by students in the undergraduate classroom to analyze, compare and contrast the glider data in real-time during the fall 2014 semester.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"274 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":"127551405","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.2014.7003016
S. Rabbi, M. Rahman, S. Butt
Electric submersible pumps (ESP) are widely used in artificial lift devices in offshore oil and gas. Induction motor drives are the current standard for ESPs. This paper presents the design, analysis and operation of energy efficient, compact and cost effective interior permanent magnet (IPM) motors for applications in ESP drive systems. The design of an original prototype IPM motor with straight-magnets orientation is presented in this paper. The performance results of a laboratory prototype 3-phase 4-pole 208V IPM motor for ESP drives are also presented and analyzed.
{"title":"Modeling and operation of an interior permanent magnet motor drive for electric submersible pumps","authors":"S. Rabbi, M. Rahman, S. Butt","doi":"10.1109/OCEANS.2014.7003016","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003016","url":null,"abstract":"Electric submersible pumps (ESP) are widely used in artificial lift devices in offshore oil and gas. Induction motor drives are the current standard for ESPs. This paper presents the design, analysis and operation of energy efficient, compact and cost effective interior permanent magnet (IPM) motors for applications in ESP drive systems. The design of an original prototype IPM motor with straight-magnets orientation is presented in this paper. The performance results of a laboratory prototype 3-phase 4-pole 208V IPM motor for ESP drives are also presented and analyzed.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"44 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":"125610650","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.2014.7003052
Liu Jia, Xu Feng, Yang Juan, An Xu-dong
The sea bottom reverberation is one of the important problems, which restrict the bottom targets detection performance with the high frequency imaging sonar. In this paper, a bottom reverberation suppression algorithm is presented to improve the performance of the high frequency side scan sonar for small target detection. In the paper, the statistics characteristic of the target echo and the bottom reverberation is introduced, with the experiment data processing. The target echo and the bottom reverberation could be separated with the difference of the statistics characteristic. And the Blind Source Separated method was applied to implement the signal separation. At last, the effective of this method was proved by the process of the experiment data.
{"title":"The bottom reverberation suppression algorithm for side scan sonar","authors":"Liu Jia, Xu Feng, Yang Juan, An Xu-dong","doi":"10.1109/OCEANS.2014.7003052","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003052","url":null,"abstract":"The sea bottom reverberation is one of the important problems, which restrict the bottom targets detection performance with the high frequency imaging sonar. In this paper, a bottom reverberation suppression algorithm is presented to improve the performance of the high frequency side scan sonar for small target detection. In the paper, the statistics characteristic of the target echo and the bottom reverberation is introduced, with the experiment data processing. The target echo and the bottom reverberation could be separated with the difference of the statistics characteristic. And the Blind Source Separated method was applied to implement the signal separation. At last, the effective of this method was proved by the process of the experiment data.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"26 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":"126660092","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.2014.7003254
E. M. Garcia, C. Chang, Hongrae Park, M. Bernitsas
Galloping motion has long been differentiated from other flow-induced motions like VIV and flutter based on the asymmetry of the flow present causing instability. Galloping instabilities can occur for circular cylinders due to proximity to a boundary or asymmetric cross-sections from strakes or other flow interference. The response of a bluff body due to galloping instabilities is still an active area of research. For VIV, such parameters as variable added mass term [1] and a damping parameter c* [2] have been introduced. This paper demonstrates that these parameters have the potential of being applied to galloping to model it as a distinct resonance phenomenon from other flow-induced motions. Additionally, it is demonstrate that the amplitudes of motion, variable added-mass, and lift are very sensitive to the added damping coefficient, but the initiation of galloping remains largely dependent on the natural frequency of the cylinder with little sensitivity to the damping.
{"title":"Effect of damping on galloping of circular cylinders","authors":"E. M. Garcia, C. Chang, Hongrae Park, M. Bernitsas","doi":"10.1109/OCEANS.2014.7003254","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003254","url":null,"abstract":"Galloping motion has long been differentiated from other flow-induced motions like VIV and flutter based on the asymmetry of the flow present causing instability. Galloping instabilities can occur for circular cylinders due to proximity to a boundary or asymmetric cross-sections from strakes or other flow interference. The response of a bluff body due to galloping instabilities is still an active area of research. For VIV, such parameters as variable added mass term [1] and a damping parameter c* [2] have been introduced. This paper demonstrates that these parameters have the potential of being applied to galloping to model it as a distinct resonance phenomenon from other flow-induced motions. Additionally, it is demonstrate that the amplitudes of motion, variable added-mass, and lift are very sensitive to the added damping coefficient, but the initiation of galloping remains largely dependent on the natural frequency of the cylinder with little sensitivity to the damping.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"55 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":"126957929","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.2014.7003280
C. D. de Moustier, P. Fox, R. Huxtable, J. C. Peterson
Results are described for a multibeam echosounder calibration experiment in which the elevation angle of a standard spherical target was estimated using a split aperture geometry on the transmit array. This is an extension of the two transmitters - one receiver concept described by Messer et al. (IEEE TAES 32-3, 1158-1164, 1996). Here, three transmitters and one receiver were used to obtain elevation angle estimates from the difference in time delays or phase delays across each baseline. The tests were conducted from a barge at dockside in about 10 m of water depth. A 500-kHz multibeam echosounder was mounted on a pan and tilt unit and deployed at the end of a pole. The tests were done using a standard tungsten-carbide sphere, 38.1 mm in diameter, suspended on a monofilament nylon line, in the far field of the transducer arrays vertically below the sonar head. Quasi-orthogonal linearly frequency modulated pulses with about 96 kHz bandwidth were transmitted in pairs (downchirp then upchirp) from each baseline. When the target remains stationary relative to the sonar for the duration of a ping pair cycle (<;0.1 s) elevation angles estimates were self-consistent within ±0.2° for the time delay method as well as for the phase delay method. Results of the two methods agreed to within 0.2° -0.3°.
{"title":"Multibeam echosounder calibration with split-aperture transmission","authors":"C. D. de Moustier, P. Fox, R. Huxtable, J. C. Peterson","doi":"10.1109/OCEANS.2014.7003280","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003280","url":null,"abstract":"Results are described for a multibeam echosounder calibration experiment in which the elevation angle of a standard spherical target was estimated using a split aperture geometry on the transmit array. This is an extension of the two transmitters - one receiver concept described by Messer et al. (IEEE TAES 32-3, 1158-1164, 1996). Here, three transmitters and one receiver were used to obtain elevation angle estimates from the difference in time delays or phase delays across each baseline. The tests were conducted from a barge at dockside in about 10 m of water depth. A 500-kHz multibeam echosounder was mounted on a pan and tilt unit and deployed at the end of a pole. The tests were done using a standard tungsten-carbide sphere, 38.1 mm in diameter, suspended on a monofilament nylon line, in the far field of the transducer arrays vertically below the sonar head. Quasi-orthogonal linearly frequency modulated pulses with about 96 kHz bandwidth were transmitted in pairs (downchirp then upchirp) from each baseline. When the target remains stationary relative to the sonar for the duration of a ping pair cycle (<;0.1 s) elevation angles estimates were self-consistent within ±0.2° for the time delay method as well as for the phase delay method. Results of the two methods agreed to within 0.2° -0.3°.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"59 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":"126090877","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.2014.7003001
Wen Wang, E. Gill
This paper presents a comparative study of conventional spectrum estimation methods, such as the periodogram method, and modern techniques, such as the autoregressive and multiple signal classification methods, for current mapping by a high frequency surface wave radar. To calculate the radial current velocity, it is important to estimate its associated Doppler shift from the frequency spectrum. In addition to the conventional centroid method, a more robust Bragg frequency identification method, termed the symmetric-peak-sum, is proposed and examined in conjunction with each of the spectral estimation techniques. It has been found that a weighted sum of the radar-derived current estimates using these two methods generally provides a lower rms difference from the buoy measurements. The weighting ratio is optimized using a genetic algorithm. Field data indicate that a combination of these spectral estimation methods is capable of providing improvements in retrieved current velocities for various current conditions.
{"title":"Comparison of spectral estimation methods for current estimation by an HF surface wave radar","authors":"Wen Wang, E. Gill","doi":"10.1109/OCEANS.2014.7003001","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003001","url":null,"abstract":"This paper presents a comparative study of conventional spectrum estimation methods, such as the periodogram method, and modern techniques, such as the autoregressive and multiple signal classification methods, for current mapping by a high frequency surface wave radar. To calculate the radial current velocity, it is important to estimate its associated Doppler shift from the frequency spectrum. In addition to the conventional centroid method, a more robust Bragg frequency identification method, termed the symmetric-peak-sum, is proposed and examined in conjunction with each of the spectral estimation techniques. It has been found that a weighted sum of the radar-derived current estimates using these two methods generally provides a lower rms difference from the buoy measurements. The weighting ratio is optimized using a genetic algorithm. Field data indicate that a combination of these spectral estimation methods is capable of providing improvements in retrieved current velocities for various current conditions.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"44 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":"126094707","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.2014.7003005
R. Diamant, L. Lampe, E. Gamroth
The ability to avoid detection of a communication signal in the underwater acoustic channel is extremely important for underwater acoustic communication (UWAC) systems when used for military-related applications. Furthermore, low probability of detection (LPD) may reduce environmental impact of UWAC as communication signals can be transmitted at lower power. In this paper, we study the LPD capability of UWAC systems. We consider an interceptor employing energy detector and calculate the minimal signal-to-noise power ratio (SNPR) which satisfies its required performance. For the receiver, we calculate the minimal required SNPR to allow reliable detection and decoding of a data packet using spread-spectrum signaling. We then analyze the LPD capability of the system for different channel and communication parameters.
{"title":"Low probability of detection for underwater acoustic communication","authors":"R. Diamant, L. Lampe, E. Gamroth","doi":"10.1109/OCEANS.2014.7003005","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003005","url":null,"abstract":"The ability to avoid detection of a communication signal in the underwater acoustic channel is extremely important for underwater acoustic communication (UWAC) systems when used for military-related applications. Furthermore, low probability of detection (LPD) may reduce environmental impact of UWAC as communication signals can be transmitted at lower power. In this paper, we study the LPD capability of UWAC systems. We consider an interceptor employing energy detector and calculate the minimal signal-to-noise power ratio (SNPR) which satisfies its required performance. For the receiver, we calculate the minimal required SNPR to allow reliable detection and decoding of a data packet using spread-spectrum signaling. We then analyze the LPD capability of the system for different channel and communication parameters.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"37 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":"115120055","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.2014.7003175
Too Yuen Min, M. Chitre
Impulsive transient signals produced by snapping shrimp dominate the high frequency ambient noise in warm shallow waters. A receiver not only observes the direct arrival of the snap from the shrimp, but also multipath reflections from scattering boundaries such as the sea surface, seabed, etc. We formulate a geometric model corresponding to one direct arrival and one surface reflection. The originating location of a snap can be extracted from the model if the exact position of each element in the receiver array is known. In practice, we only have coarse prior knowledge of the array depth and orientation, and the exact array element locations have to be estimated. The situation is further complicated by the fact that many snaps occur concurrently, and associating a snap with its reflection is a nontrivial problem. We use least logarithmic absolute (LLA) criteria to explore the unknown parameter in this joint estimation and association problem. The association can be further refined based on the complete geometric model. We outline our method and present a numerical simulation to test the performance of the estimator. Results from a dataset collected in Singapore waters using a broadband small-aperture phased array are illustrated. We compare the results with previous findings, demonstrating that accurate passive localization of known structures in the ocean using natural noise made by snapping shrimp inhabiting the structures can be achieved.
{"title":"Localization of impulsive sources in the ocean using the method of images","authors":"Too Yuen Min, M. Chitre","doi":"10.1109/OCEANS.2014.7003175","DOIUrl":"https://doi.org/10.1109/OCEANS.2014.7003175","url":null,"abstract":"Impulsive transient signals produced by snapping shrimp dominate the high frequency ambient noise in warm shallow waters. A receiver not only observes the direct arrival of the snap from the shrimp, but also multipath reflections from scattering boundaries such as the sea surface, seabed, etc. We formulate a geometric model corresponding to one direct arrival and one surface reflection. The originating location of a snap can be extracted from the model if the exact position of each element in the receiver array is known. In practice, we only have coarse prior knowledge of the array depth and orientation, and the exact array element locations have to be estimated. The situation is further complicated by the fact that many snaps occur concurrently, and associating a snap with its reflection is a nontrivial problem. We use least logarithmic absolute (LLA) criteria to explore the unknown parameter in this joint estimation and association problem. The association can be further refined based on the complete geometric model. We outline our method and present a numerical simulation to test the performance of the estimator. Results from a dataset collected in Singapore waters using a broadband small-aperture phased array are illustrated. We compare the results with previous findings, demonstrating that accurate passive localization of known structures in the ocean using natural noise made by snapping shrimp inhabiting the structures can be achieved.","PeriodicalId":368693,"journal":{"name":"2014 Oceans - St. John's","volume":"130 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":"125788535","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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