The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Harry J. Simpson - One of the best experts on this subject based on the ideXlab platform.
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Measurements and modeling of acoustic scattering from targets in Littoral Environments
The Journal of the Acoustical Society of America, 2014Co-Authors: Harry J. Simpson, Brian H. Houston, Zackary J. Waters, Timothy J. Yoder, Kyrie K. Jig, Roger R. Volk, Joseph A. BucaroAbstract:Broadband laboratory and at-sea measurements systems have been built by NRL to quantify the acoustic target strength of objects sitting on or in the bottom of Littoral Environments. Over the past decade, these measurements and the subsequent modeling of the target strength have helped to develop an understanding of how the Environment, especially near the bottom interface, impacts the structural acoustic response of a variety of objects. In this talk we will present a set of laboratory, at-sea rail and AUV based back scatter, forward scatter, and propagation measurements with subsequent analysis to understand the impact of the Littoral Environment. Simple targets such as spheres, along with UXO targets will be discussed. The analysis will be focused on quantifying the changes to target strength as a result of being near the bottom interface. In addition to the traditional backscatter or monosatic target strength, we focus upon efforts to investigate the multi-static scattering from targets. [Work supporte...
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forward scatter and backscatter low frequency synthetic array measurements of the structural acoustic response from proud targets using a 48 m long rail in a Littoral Environment
Journal of the Acoustical Society of America, 2010Co-Authors: Harry J. Simpson, Larry A. Kraus, Alain R. Berdoz, Danial L. Amon, Philip A. Frank, Steve W. Liskey, Brian H. Houston, David C. Calvo, Zachary J. Waters, J A BucaroAbstract:A series of short range (25‐m) forward scatter and backscatter measurements in a Littoral Environment was conducted to quantify the structural acoustic response from proud targets in the 2–23 kHz frequency band. The water channel was 14 m deep in the Gulf of Mexico near Shell Island, Panama City FL. The bottom was a medium grained sand. The acoustic forward scatter response of the proud targets was measured in a bistatic configuration with the source 25 m from the target and a receiver mounted on a 48‐m‐long rail. The rail is used to position the receiver and synthetically quantify the structural acoustic forward scatter response. A second source was co‐located with the receiver on the rail, and monostatic backscatter measurements were also taken for each target. The structural acoustic response was analyzed and will be reported. The synthetic array experimental results are compared and contrasted with laboratory measurements. The laboratory measurements are convolved with water channel propagation predic...
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Forward scatter target strength extraction in a Littoral Environment.
The Journal of the Acoustical Society of America, 2010Co-Authors: Larry A. Kraus, Alain R. Berdoz, Danial L. Amon, Philip A. Frank, Steve W. Liskey, Joseph A. Bucaro, Harry J. Simpson, Brian H. Houston, David C. CalvoAbstract:A rail‐based system was used to collect forward and near‐forward scattered echoes from a spherical shell in 14‐m waters near Shell Island, Panama City, FL. The source was positioned 25 m from the scattering target and the 48‐m horizontal rail on the opposite side, also 25 m from the target. The major obstacle to obtaining high‐quality forward scatter target strength versus frequency and angle is the extraction of the much stronger time and position overlapping incident source signal. In previous laboratory measurements, this is accomplished with high precision by direct measurement of the incident field before the scattering target is positioned, a method not possible in a target search scenario or in a less stable Environment. Here an attempt is made to obtain the forward scattered target strength by post‐processing the received signals obtained in the Littoral Environment which contain both the echo and the overlapping source signal. The methodology involves using a wavenumber domain filter to remove the incident wave followed by standard synthetic aperture procedures to extract the desired target scattered signal. The resulting forward scattered target strength will be compared to what we expect analytically and experimentally from this simple target. [Work supported by ONR].
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Forward scatter and backscatter low‐frequency synthetic array measurements of the structural acoustic response from proud targets using a 48‐m‐long rail in a Littoral Environment.
The Journal of the Acoustical Society of America, 2010Co-Authors: Harry J. Simpson, Larry A. Kraus, Alain R. Berdoz, Danial L. Amon, Philip A. Frank, Steve W. Liskey, Brian H. Houston, David C. Calvo, Zachary J. Waters, Joseph A. BucaroAbstract:A series of short range (25‐m) forward scatter and backscatter measurements in a Littoral Environment was conducted to quantify the structural acoustic response from proud targets in the 2–23 kHz frequency band. The water channel was 14 m deep in the Gulf of Mexico near Shell Island, Panama City FL. The bottom was a medium grained sand. The acoustic forward scatter response of the proud targets was measured in a bistatic configuration with the source 25 m from the target and a receiver mounted on a 48‐m‐long rail. The rail is used to position the receiver and synthetically quantify the structural acoustic forward scatter response. A second source was co‐located with the receiver on the rail, and monostatic backscatter measurements were also taken for each target. The structural acoustic response was analyzed and will be reported. The synthetic array experimental results are compared and contrasted with laboratory measurements. The laboratory measurements are convolved with water channel propagation predic...
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Measurements of sound propagation in a Littoral Environment using a vertical synthetic array
The Journal of the Acoustical Society of America, 2007Co-Authors: Harry J. Simpson, Larry A. Kraus, Alain R. Berdoz, Philip A. Frank, Steve W. Liskey, Brian H. Houston, Carl K. Frederickson, Erik C. Porse, Steve StanicAbstract:Shallow-water propagation experiments were carried out in St. Andrews Bay, Florida. These investigations used a vertical one-dimensional synthetic array measurement system where two hydrophones incrementally mapped the acoustic pressure from 2m below through 2m above the sand-water interface. A broadband (1 to 12kHz) chirp was used to insonify the water channel. The source to receiver distance was varied and included measurements at 20, 30, 50, 70, and 90m. These measurements quantified the acoustic pressure above and below a sandy bottom and the results are presented along with frequency analysis, temporal impulse analysis, and wave number analysis. To obtain a better understanding of the results, the measurements are compared to two numerical models. The first model is a temporal ray path prediction of sound propagation in the water channel. The second model, range-dependent acoustic model (RAM), based on a parabolic equation, predicts the sound propagating in a water channel with a sandy bottom. The ex...
Steve W. Liskey - One of the best experts on this subject based on the ideXlab platform.
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forward scatter and backscatter low frequency synthetic array measurements of the structural acoustic response from proud targets using a 48 m long rail in a Littoral Environment
Journal of the Acoustical Society of America, 2010Co-Authors: Harry J. Simpson, Larry A. Kraus, Alain R. Berdoz, Danial L. Amon, Philip A. Frank, Steve W. Liskey, Brian H. Houston, David C. Calvo, Zachary J. Waters, J A BucaroAbstract:A series of short range (25‐m) forward scatter and backscatter measurements in a Littoral Environment was conducted to quantify the structural acoustic response from proud targets in the 2–23 kHz frequency band. The water channel was 14 m deep in the Gulf of Mexico near Shell Island, Panama City FL. The bottom was a medium grained sand. The acoustic forward scatter response of the proud targets was measured in a bistatic configuration with the source 25 m from the target and a receiver mounted on a 48‐m‐long rail. The rail is used to position the receiver and synthetically quantify the structural acoustic forward scatter response. A second source was co‐located with the receiver on the rail, and monostatic backscatter measurements were also taken for each target. The structural acoustic response was analyzed and will be reported. The synthetic array experimental results are compared and contrasted with laboratory measurements. The laboratory measurements are convolved with water channel propagation predic...
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Forward scatter target strength extraction in a Littoral Environment.
The Journal of the Acoustical Society of America, 2010Co-Authors: Larry A. Kraus, Alain R. Berdoz, Danial L. Amon, Philip A. Frank, Steve W. Liskey, Joseph A. Bucaro, Harry J. Simpson, Brian H. Houston, David C. CalvoAbstract:A rail‐based system was used to collect forward and near‐forward scattered echoes from a spherical shell in 14‐m waters near Shell Island, Panama City, FL. The source was positioned 25 m from the scattering target and the 48‐m horizontal rail on the opposite side, also 25 m from the target. The major obstacle to obtaining high‐quality forward scatter target strength versus frequency and angle is the extraction of the much stronger time and position overlapping incident source signal. In previous laboratory measurements, this is accomplished with high precision by direct measurement of the incident field before the scattering target is positioned, a method not possible in a target search scenario or in a less stable Environment. Here an attempt is made to obtain the forward scattered target strength by post‐processing the received signals obtained in the Littoral Environment which contain both the echo and the overlapping source signal. The methodology involves using a wavenumber domain filter to remove the incident wave followed by standard synthetic aperture procedures to extract the desired target scattered signal. The resulting forward scattered target strength will be compared to what we expect analytically and experimentally from this simple target. [Work supported by ONR].
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Forward scatter and backscatter low‐frequency synthetic array measurements of the structural acoustic response from proud targets using a 48‐m‐long rail in a Littoral Environment.
The Journal of the Acoustical Society of America, 2010Co-Authors: Harry J. Simpson, Larry A. Kraus, Alain R. Berdoz, Danial L. Amon, Philip A. Frank, Steve W. Liskey, Brian H. Houston, David C. Calvo, Zachary J. Waters, Joseph A. BucaroAbstract:A series of short range (25‐m) forward scatter and backscatter measurements in a Littoral Environment was conducted to quantify the structural acoustic response from proud targets in the 2–23 kHz frequency band. The water channel was 14 m deep in the Gulf of Mexico near Shell Island, Panama City FL. The bottom was a medium grained sand. The acoustic forward scatter response of the proud targets was measured in a bistatic configuration with the source 25 m from the target and a receiver mounted on a 48‐m‐long rail. The rail is used to position the receiver and synthetically quantify the structural acoustic forward scatter response. A second source was co‐located with the receiver on the rail, and monostatic backscatter measurements were also taken for each target. The structural acoustic response was analyzed and will be reported. The synthetic array experimental results are compared and contrasted with laboratory measurements. The laboratory measurements are convolved with water channel propagation predic...
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Measurements of sound propagation in a Littoral Environment using a vertical synthetic array
The Journal of the Acoustical Society of America, 2007Co-Authors: Harry J. Simpson, Larry A. Kraus, Alain R. Berdoz, Philip A. Frank, Steve W. Liskey, Brian H. Houston, Carl K. Frederickson, Erik C. Porse, Steve StanicAbstract:Shallow-water propagation experiments were carried out in St. Andrews Bay, Florida. These investigations used a vertical one-dimensional synthetic array measurement system where two hydrophones incrementally mapped the acoustic pressure from 2m below through 2m above the sand-water interface. A broadband (1 to 12kHz) chirp was used to insonify the water channel. The source to receiver distance was varied and included measurements at 20, 30, 50, 70, and 90m. These measurements quantified the acoustic pressure above and below a sandy bottom and the results are presented along with frequency analysis, temporal impulse analysis, and wave number analysis. To obtain a better understanding of the results, the measurements are compared to two numerical models. The first model is a temporal ray path prediction of sound propagation in the water channel. The second model, range-dependent acoustic model (RAM), based on a parabolic equation, predicts the sound propagating in a water channel with a sandy bottom. The ex...
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very low frequency scattering experiments from proud targets in a Littoral Environment using a 55 m rail
Journal of the Acoustical Society of America, 2003Co-Authors: Harry J. Simpson, Larry A. Kraus, Alain R. Berdoz, Philip A. Frank, Brian H. Houston, Carl K. Frederickson, Erik C. Porse, Steve W. LiskeyAbstract:Scattering measurements from proud targets were conducted in the Littoral Environment of St. Andrews bay. A 55‐m long rail was assembled 2.3 m above the sandy bottom to position transducers using an attached robot. The rail provided a straight and level structure that repeatably scanned the target field. This system was used in both a bistatic and monostatic configuration to produce synthetic array measurements of the target field. The bistatic experiments used a stationary source at the center of the rail to insonify the target field while the receiver was moved to synthesize a 55‐m array. The monostatic experiments had both a source and receiver mounted together on the robot, and both were moved together to scan the target field. All the experiments were conducted using a very‐low‐frequency band (1 to 12 kHz). The results of these experiments will be presented along with signal processing of the target field to study the physical responses of the individual targets to the low‐frequency acoustic insonification. [Work supported by ONR.]
Brian H. Houston - One of the best experts on this subject based on the ideXlab platform.
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Measurements and modeling of acoustic scattering from targets in Littoral Environments
The Journal of the Acoustical Society of America, 2014Co-Authors: Harry J. Simpson, Brian H. Houston, Zackary J. Waters, Timothy J. Yoder, Kyrie K. Jig, Roger R. Volk, Joseph A. BucaroAbstract:Broadband laboratory and at-sea measurements systems have been built by NRL to quantify the acoustic target strength of objects sitting on or in the bottom of Littoral Environments. Over the past decade, these measurements and the subsequent modeling of the target strength have helped to develop an understanding of how the Environment, especially near the bottom interface, impacts the structural acoustic response of a variety of objects. In this talk we will present a set of laboratory, at-sea rail and AUV based back scatter, forward scatter, and propagation measurements with subsequent analysis to understand the impact of the Littoral Environment. Simple targets such as spheres, along with UXO targets will be discussed. The analysis will be focused on quantifying the changes to target strength as a result of being near the bottom interface. In addition to the traditional backscatter or monosatic target strength, we focus upon efforts to investigate the multi-static scattering from targets. [Work supporte...
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forward scatter and backscatter low frequency synthetic array measurements of the structural acoustic response from proud targets using a 48 m long rail in a Littoral Environment
Journal of the Acoustical Society of America, 2010Co-Authors: Harry J. Simpson, Larry A. Kraus, Alain R. Berdoz, Danial L. Amon, Philip A. Frank, Steve W. Liskey, Brian H. Houston, David C. Calvo, Zachary J. Waters, J A BucaroAbstract:A series of short range (25‐m) forward scatter and backscatter measurements in a Littoral Environment was conducted to quantify the structural acoustic response from proud targets in the 2–23 kHz frequency band. The water channel was 14 m deep in the Gulf of Mexico near Shell Island, Panama City FL. The bottom was a medium grained sand. The acoustic forward scatter response of the proud targets was measured in a bistatic configuration with the source 25 m from the target and a receiver mounted on a 48‐m‐long rail. The rail is used to position the receiver and synthetically quantify the structural acoustic forward scatter response. A second source was co‐located with the receiver on the rail, and monostatic backscatter measurements were also taken for each target. The structural acoustic response was analyzed and will be reported. The synthetic array experimental results are compared and contrasted with laboratory measurements. The laboratory measurements are convolved with water channel propagation predic...
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Forward scatter target strength extraction in a Littoral Environment.
The Journal of the Acoustical Society of America, 2010Co-Authors: Larry A. Kraus, Alain R. Berdoz, Danial L. Amon, Philip A. Frank, Steve W. Liskey, Joseph A. Bucaro, Harry J. Simpson, Brian H. Houston, David C. CalvoAbstract:A rail‐based system was used to collect forward and near‐forward scattered echoes from a spherical shell in 14‐m waters near Shell Island, Panama City, FL. The source was positioned 25 m from the scattering target and the 48‐m horizontal rail on the opposite side, also 25 m from the target. The major obstacle to obtaining high‐quality forward scatter target strength versus frequency and angle is the extraction of the much stronger time and position overlapping incident source signal. In previous laboratory measurements, this is accomplished with high precision by direct measurement of the incident field before the scattering target is positioned, a method not possible in a target search scenario or in a less stable Environment. Here an attempt is made to obtain the forward scattered target strength by post‐processing the received signals obtained in the Littoral Environment which contain both the echo and the overlapping source signal. The methodology involves using a wavenumber domain filter to remove the incident wave followed by standard synthetic aperture procedures to extract the desired target scattered signal. The resulting forward scattered target strength will be compared to what we expect analytically and experimentally from this simple target. [Work supported by ONR].
-
Forward scatter and backscatter low‐frequency synthetic array measurements of the structural acoustic response from proud targets using a 48‐m‐long rail in a Littoral Environment.
The Journal of the Acoustical Society of America, 2010Co-Authors: Harry J. Simpson, Larry A. Kraus, Alain R. Berdoz, Danial L. Amon, Philip A. Frank, Steve W. Liskey, Brian H. Houston, David C. Calvo, Zachary J. Waters, Joseph A. BucaroAbstract:A series of short range (25‐m) forward scatter and backscatter measurements in a Littoral Environment was conducted to quantify the structural acoustic response from proud targets in the 2–23 kHz frequency band. The water channel was 14 m deep in the Gulf of Mexico near Shell Island, Panama City FL. The bottom was a medium grained sand. The acoustic forward scatter response of the proud targets was measured in a bistatic configuration with the source 25 m from the target and a receiver mounted on a 48‐m‐long rail. The rail is used to position the receiver and synthetically quantify the structural acoustic forward scatter response. A second source was co‐located with the receiver on the rail, and monostatic backscatter measurements were also taken for each target. The structural acoustic response was analyzed and will be reported. The synthetic array experimental results are compared and contrasted with laboratory measurements. The laboratory measurements are convolved with water channel propagation predic...
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Measurements of sound propagation in a Littoral Environment using a vertical synthetic array
The Journal of the Acoustical Society of America, 2007Co-Authors: Harry J. Simpson, Larry A. Kraus, Alain R. Berdoz, Philip A. Frank, Steve W. Liskey, Brian H. Houston, Carl K. Frederickson, Erik C. Porse, Steve StanicAbstract:Shallow-water propagation experiments were carried out in St. Andrews Bay, Florida. These investigations used a vertical one-dimensional synthetic array measurement system where two hydrophones incrementally mapped the acoustic pressure from 2m below through 2m above the sand-water interface. A broadband (1 to 12kHz) chirp was used to insonify the water channel. The source to receiver distance was varied and included measurements at 20, 30, 50, 70, and 90m. These measurements quantified the acoustic pressure above and below a sandy bottom and the results are presented along with frequency analysis, temporal impulse analysis, and wave number analysis. To obtain a better understanding of the results, the measurements are compared to two numerical models. The first model is a temporal ray path prediction of sound propagation in the water channel. The second model, range-dependent acoustic model (RAM), based on a parabolic equation, predicts the sound propagating in a water channel with a sandy bottom. The ex...
Larry A. Kraus - One of the best experts on this subject based on the ideXlab platform.
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forward scatter and backscatter low frequency synthetic array measurements of the structural acoustic response from proud targets using a 48 m long rail in a Littoral Environment
Journal of the Acoustical Society of America, 2010Co-Authors: Harry J. Simpson, Larry A. Kraus, Alain R. Berdoz, Danial L. Amon, Philip A. Frank, Steve W. Liskey, Brian H. Houston, David C. Calvo, Zachary J. Waters, J A BucaroAbstract:A series of short range (25‐m) forward scatter and backscatter measurements in a Littoral Environment was conducted to quantify the structural acoustic response from proud targets in the 2–23 kHz frequency band. The water channel was 14 m deep in the Gulf of Mexico near Shell Island, Panama City FL. The bottom was a medium grained sand. The acoustic forward scatter response of the proud targets was measured in a bistatic configuration with the source 25 m from the target and a receiver mounted on a 48‐m‐long rail. The rail is used to position the receiver and synthetically quantify the structural acoustic forward scatter response. A second source was co‐located with the receiver on the rail, and monostatic backscatter measurements were also taken for each target. The structural acoustic response was analyzed and will be reported. The synthetic array experimental results are compared and contrasted with laboratory measurements. The laboratory measurements are convolved with water channel propagation predic...
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Forward scatter target strength extraction in a Littoral Environment.
The Journal of the Acoustical Society of America, 2010Co-Authors: Larry A. Kraus, Alain R. Berdoz, Danial L. Amon, Philip A. Frank, Steve W. Liskey, Joseph A. Bucaro, Harry J. Simpson, Brian H. Houston, David C. CalvoAbstract:A rail‐based system was used to collect forward and near‐forward scattered echoes from a spherical shell in 14‐m waters near Shell Island, Panama City, FL. The source was positioned 25 m from the scattering target and the 48‐m horizontal rail on the opposite side, also 25 m from the target. The major obstacle to obtaining high‐quality forward scatter target strength versus frequency and angle is the extraction of the much stronger time and position overlapping incident source signal. In previous laboratory measurements, this is accomplished with high precision by direct measurement of the incident field before the scattering target is positioned, a method not possible in a target search scenario or in a less stable Environment. Here an attempt is made to obtain the forward scattered target strength by post‐processing the received signals obtained in the Littoral Environment which contain both the echo and the overlapping source signal. The methodology involves using a wavenumber domain filter to remove the incident wave followed by standard synthetic aperture procedures to extract the desired target scattered signal. The resulting forward scattered target strength will be compared to what we expect analytically and experimentally from this simple target. [Work supported by ONR].
-
Forward scatter and backscatter low‐frequency synthetic array measurements of the structural acoustic response from proud targets using a 48‐m‐long rail in a Littoral Environment.
The Journal of the Acoustical Society of America, 2010Co-Authors: Harry J. Simpson, Larry A. Kraus, Alain R. Berdoz, Danial L. Amon, Philip A. Frank, Steve W. Liskey, Brian H. Houston, David C. Calvo, Zachary J. Waters, Joseph A. BucaroAbstract:A series of short range (25‐m) forward scatter and backscatter measurements in a Littoral Environment was conducted to quantify the structural acoustic response from proud targets in the 2–23 kHz frequency band. The water channel was 14 m deep in the Gulf of Mexico near Shell Island, Panama City FL. The bottom was a medium grained sand. The acoustic forward scatter response of the proud targets was measured in a bistatic configuration with the source 25 m from the target and a receiver mounted on a 48‐m‐long rail. The rail is used to position the receiver and synthetically quantify the structural acoustic forward scatter response. A second source was co‐located with the receiver on the rail, and monostatic backscatter measurements were also taken for each target. The structural acoustic response was analyzed and will be reported. The synthetic array experimental results are compared and contrasted with laboratory measurements. The laboratory measurements are convolved with water channel propagation predic...
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Measurements of sound propagation in a Littoral Environment using a vertical synthetic array
The Journal of the Acoustical Society of America, 2007Co-Authors: Harry J. Simpson, Larry A. Kraus, Alain R. Berdoz, Philip A. Frank, Steve W. Liskey, Brian H. Houston, Carl K. Frederickson, Erik C. Porse, Steve StanicAbstract:Shallow-water propagation experiments were carried out in St. Andrews Bay, Florida. These investigations used a vertical one-dimensional synthetic array measurement system where two hydrophones incrementally mapped the acoustic pressure from 2m below through 2m above the sand-water interface. A broadband (1 to 12kHz) chirp was used to insonify the water channel. The source to receiver distance was varied and included measurements at 20, 30, 50, 70, and 90m. These measurements quantified the acoustic pressure above and below a sandy bottom and the results are presented along with frequency analysis, temporal impulse analysis, and wave number analysis. To obtain a better understanding of the results, the measurements are compared to two numerical models. The first model is a temporal ray path prediction of sound propagation in the water channel. The second model, range-dependent acoustic model (RAM), based on a parabolic equation, predicts the sound propagating in a water channel with a sandy bottom. The ex...
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very low frequency scattering experiments from proud targets in a Littoral Environment using a 55 m rail
Journal of the Acoustical Society of America, 2003Co-Authors: Harry J. Simpson, Larry A. Kraus, Alain R. Berdoz, Philip A. Frank, Brian H. Houston, Carl K. Frederickson, Erik C. Porse, Steve W. LiskeyAbstract:Scattering measurements from proud targets were conducted in the Littoral Environment of St. Andrews bay. A 55‐m long rail was assembled 2.3 m above the sandy bottom to position transducers using an attached robot. The rail provided a straight and level structure that repeatably scanned the target field. This system was used in both a bistatic and monostatic configuration to produce synthetic array measurements of the target field. The bistatic experiments used a stationary source at the center of the rail to insonify the target field while the receiver was moved to synthesize a 55‐m array. The monostatic experiments had both a source and receiver mounted together on the robot, and both were moved together to scan the target field. All the experiments were conducted using a very‐low‐frequency band (1 to 12 kHz). The results of these experiments will be presented along with signal processing of the target field to study the physical responses of the individual targets to the low‐frequency acoustic insonification. [Work supported by ONR.]
Alain R. Berdoz - One of the best experts on this subject based on the ideXlab platform.
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forward scatter and backscatter low frequency synthetic array measurements of the structural acoustic response from proud targets using a 48 m long rail in a Littoral Environment
Journal of the Acoustical Society of America, 2010Co-Authors: Harry J. Simpson, Larry A. Kraus, Alain R. Berdoz, Danial L. Amon, Philip A. Frank, Steve W. Liskey, Brian H. Houston, David C. Calvo, Zachary J. Waters, J A BucaroAbstract:A series of short range (25‐m) forward scatter and backscatter measurements in a Littoral Environment was conducted to quantify the structural acoustic response from proud targets in the 2–23 kHz frequency band. The water channel was 14 m deep in the Gulf of Mexico near Shell Island, Panama City FL. The bottom was a medium grained sand. The acoustic forward scatter response of the proud targets was measured in a bistatic configuration with the source 25 m from the target and a receiver mounted on a 48‐m‐long rail. The rail is used to position the receiver and synthetically quantify the structural acoustic forward scatter response. A second source was co‐located with the receiver on the rail, and monostatic backscatter measurements were also taken for each target. The structural acoustic response was analyzed and will be reported. The synthetic array experimental results are compared and contrasted with laboratory measurements. The laboratory measurements are convolved with water channel propagation predic...
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Forward scatter target strength extraction in a Littoral Environment.
The Journal of the Acoustical Society of America, 2010Co-Authors: Larry A. Kraus, Alain R. Berdoz, Danial L. Amon, Philip A. Frank, Steve W. Liskey, Joseph A. Bucaro, Harry J. Simpson, Brian H. Houston, David C. CalvoAbstract:A rail‐based system was used to collect forward and near‐forward scattered echoes from a spherical shell in 14‐m waters near Shell Island, Panama City, FL. The source was positioned 25 m from the scattering target and the 48‐m horizontal rail on the opposite side, also 25 m from the target. The major obstacle to obtaining high‐quality forward scatter target strength versus frequency and angle is the extraction of the much stronger time and position overlapping incident source signal. In previous laboratory measurements, this is accomplished with high precision by direct measurement of the incident field before the scattering target is positioned, a method not possible in a target search scenario or in a less stable Environment. Here an attempt is made to obtain the forward scattered target strength by post‐processing the received signals obtained in the Littoral Environment which contain both the echo and the overlapping source signal. The methodology involves using a wavenumber domain filter to remove the incident wave followed by standard synthetic aperture procedures to extract the desired target scattered signal. The resulting forward scattered target strength will be compared to what we expect analytically and experimentally from this simple target. [Work supported by ONR].
-
Forward scatter and backscatter low‐frequency synthetic array measurements of the structural acoustic response from proud targets using a 48‐m‐long rail in a Littoral Environment.
The Journal of the Acoustical Society of America, 2010Co-Authors: Harry J. Simpson, Larry A. Kraus, Alain R. Berdoz, Danial L. Amon, Philip A. Frank, Steve W. Liskey, Brian H. Houston, David C. Calvo, Zachary J. Waters, Joseph A. BucaroAbstract:A series of short range (25‐m) forward scatter and backscatter measurements in a Littoral Environment was conducted to quantify the structural acoustic response from proud targets in the 2–23 kHz frequency band. The water channel was 14 m deep in the Gulf of Mexico near Shell Island, Panama City FL. The bottom was a medium grained sand. The acoustic forward scatter response of the proud targets was measured in a bistatic configuration with the source 25 m from the target and a receiver mounted on a 48‐m‐long rail. The rail is used to position the receiver and synthetically quantify the structural acoustic forward scatter response. A second source was co‐located with the receiver on the rail, and monostatic backscatter measurements were also taken for each target. The structural acoustic response was analyzed and will be reported. The synthetic array experimental results are compared and contrasted with laboratory measurements. The laboratory measurements are convolved with water channel propagation predic...
-
Measurements of sound propagation in a Littoral Environment using a vertical synthetic array
The Journal of the Acoustical Society of America, 2007Co-Authors: Harry J. Simpson, Larry A. Kraus, Alain R. Berdoz, Philip A. Frank, Steve W. Liskey, Brian H. Houston, Carl K. Frederickson, Erik C. Porse, Steve StanicAbstract:Shallow-water propagation experiments were carried out in St. Andrews Bay, Florida. These investigations used a vertical one-dimensional synthetic array measurement system where two hydrophones incrementally mapped the acoustic pressure from 2m below through 2m above the sand-water interface. A broadband (1 to 12kHz) chirp was used to insonify the water channel. The source to receiver distance was varied and included measurements at 20, 30, 50, 70, and 90m. These measurements quantified the acoustic pressure above and below a sandy bottom and the results are presented along with frequency analysis, temporal impulse analysis, and wave number analysis. To obtain a better understanding of the results, the measurements are compared to two numerical models. The first model is a temporal ray path prediction of sound propagation in the water channel. The second model, range-dependent acoustic model (RAM), based on a parabolic equation, predicts the sound propagating in a water channel with a sandy bottom. The ex...
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very low frequency scattering experiments from proud targets in a Littoral Environment using a 55 m rail
Journal of the Acoustical Society of America, 2003Co-Authors: Harry J. Simpson, Larry A. Kraus, Alain R. Berdoz, Philip A. Frank, Brian H. Houston, Carl K. Frederickson, Erik C. Porse, Steve W. LiskeyAbstract:Scattering measurements from proud targets were conducted in the Littoral Environment of St. Andrews bay. A 55‐m long rail was assembled 2.3 m above the sandy bottom to position transducers using an attached robot. The rail provided a straight and level structure that repeatably scanned the target field. This system was used in both a bistatic and monostatic configuration to produce synthetic array measurements of the target field. The bistatic experiments used a stationary source at the center of the rail to insonify the target field while the receiver was moved to synthesize a 55‐m array. The monostatic experiments had both a source and receiver mounted together on the robot, and both were moved together to scan the target field. All the experiments were conducted using a very‐low‐frequency band (1 to 12 kHz). The results of these experiments will be presented along with signal processing of the target field to study the physical responses of the individual targets to the low‐frequency acoustic insonification. [Work supported by ONR.]