Pub Date : 1993-10-18DOI: 10.1109/OCEANS.1993.326141
K. V. Jorgensen, B. L. Grose, F. Crandall
Doppler sonars have been used for many years to aid underwater navigational systems, reducing their complexity and enhancing their accuracy. This paper describes recent improvements that significantly advance Doppler performance. A new, state-of-the-art, phased array transducer has been developed which offers a number of significant operational advantages. Among these improvements, the phased array eliminates speed of sound dependency, a principle error source in older designs. The conformal surface of the array also eliminates turbulence and simplifies array mounting. Performance advances have also been achieved by the use of digital signal processing (DSP) techniques. Adaptive bandwidth tracking filters and the use of a maximal likelihood digital spectral estimator, have greatly improved available accuracy. Recent advances in manufacturing techniques have made a miniaturized system optimized for autonomous underwater vehicle (AUV) practical.<>
{"title":"Doppler sonar applied to precision underwater navigation","authors":"K. V. Jorgensen, B. L. Grose, F. Crandall","doi":"10.1109/OCEANS.1993.326141","DOIUrl":"https://doi.org/10.1109/OCEANS.1993.326141","url":null,"abstract":"Doppler sonars have been used for many years to aid underwater navigational systems, reducing their complexity and enhancing their accuracy. This paper describes recent improvements that significantly advance Doppler performance. A new, state-of-the-art, phased array transducer has been developed which offers a number of significant operational advantages. Among these improvements, the phased array eliminates speed of sound dependency, a principle error source in older designs. The conformal surface of the array also eliminates turbulence and simplifies array mounting. Performance advances have also been achieved by the use of digital signal processing (DSP) techniques. Adaptive bandwidth tracking filters and the use of a maximal likelihood digital spectral estimator, have greatly improved available accuracy. Recent advances in manufacturing techniques have made a miniaturized system optimized for autonomous underwater vehicle (AUV) practical.<<ETX>>","PeriodicalId":130255,"journal":{"name":"Proceedings of OCEANS '93","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121387344","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 : 1993-10-18DOI: 10.1109/OCEANS.1993.326006
D. R. Haller, D. Lemon
A sonar transmission signal that has enhanced the operation of conventional 50 kHz depth sounders in noise-limited environments has been applied to a sidescan sonar application where the acoustic background is dominated by reverberation. By transmitting a pseudorandom noise (PRN) source pulse with a high bandwidth-time product, and detecting the returned signals by cross-correlation with the source waveform, the potential processing gain is greatly increased and high resolution in both time end frequency is achieved. In a sidescan application, the depth-sounder transducer was aimed horizontally and driven with a variety of PRN coded and uncoded source signals. An artificial target array was deployed on the bottom at a shallow water test site to simulate a cluttered background against which detection performance for pre-existing bottom targets could be evaluated. Detection performance of the PRN coded signals has been found superior to all uncoded signal types both for cluttered and uncluttered backgrounds.<>
{"title":"Sidescan sonar detection performance with PRN coded signals","authors":"D. R. Haller, D. Lemon","doi":"10.1109/OCEANS.1993.326006","DOIUrl":"https://doi.org/10.1109/OCEANS.1993.326006","url":null,"abstract":"A sonar transmission signal that has enhanced the operation of conventional 50 kHz depth sounders in noise-limited environments has been applied to a sidescan sonar application where the acoustic background is dominated by reverberation. By transmitting a pseudorandom noise (PRN) source pulse with a high bandwidth-time product, and detecting the returned signals by cross-correlation with the source waveform, the potential processing gain is greatly increased and high resolution in both time end frequency is achieved. In a sidescan application, the depth-sounder transducer was aimed horizontally and driven with a variety of PRN coded and uncoded source signals. An artificial target array was deployed on the bottom at a shallow water test site to simulate a cluttered background against which detection performance for pre-existing bottom targets could be evaluated. Detection performance of the PRN coded signals has been found superior to all uncoded signal types both for cluttered and uncluttered backgrounds.<<ETX>>","PeriodicalId":130255,"journal":{"name":"Proceedings of OCEANS '93","volume":"429 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115948006","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 : 1993-10-18DOI: 10.1109/OCEANS.1993.326085
R. Baumert, D. Epp
Ballard Power Systems Inc. is developing fuel cell propulsion systems for undersea applications. One of the key development issues in this process is the safe, practical storage and delivery of hydrogen fuel. Various storage methods are discussed and compared. Some methods have significant potential for the undersea environment, but will require further development before they will be feasible for full-scale applications.<>
{"title":"Hydrogen storage for fuel cell powered underwater vehicles","authors":"R. Baumert, D. Epp","doi":"10.1109/OCEANS.1993.326085","DOIUrl":"https://doi.org/10.1109/OCEANS.1993.326085","url":null,"abstract":"Ballard Power Systems Inc. is developing fuel cell propulsion systems for undersea applications. One of the key development issues in this process is the safe, practical storage and delivery of hydrogen fuel. Various storage methods are discussed and compared. Some methods have significant potential for the undersea environment, but will require further development before they will be feasible for full-scale applications.<<ETX>>","PeriodicalId":130255,"journal":{"name":"Proceedings of OCEANS '93","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116714896","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 : 1993-10-18DOI: 10.1109/OCEANS.1993.326204
A. Schmidt, V. Wismann, R. Romeiser, W. Alpers
Quasi-simultaneous measurements of the ocean wave-radar modulation transfer function (MTF) were performed from the German North Sea Research Platform (FPN) at 1.0 GHz (L-band), 53 GHz (C-band), and 10.0 GHz (X-band) at HH and VV polarization by using one antenna. MTFs obtained at different radar frequencies and polarizations are compared. The results show that the coherence between the radar backscatter and the long ocean wave field is a strongly decreasing function of radar frequency. A residual MTF, M/sub res/ is calculated which is obtained by subtracting the theoretical tilt and range MTFs from the measured total MTF. According to conventional theory, M/sub res/ should be identical to the hydrodynamic MTF and therefore be independent of polarization. However, the experimental data show a strong dependence of the magnitude and phase of M/sub res/ on polarization. The differences between M/sub res/ obtained at HR and VV polarization can partly be explained by a three-scale composite surface model.<>
{"title":"Tower based measurements of the ocean wave radar modulation transfer function with a three-frequency scatterometer","authors":"A. Schmidt, V. Wismann, R. Romeiser, W. Alpers","doi":"10.1109/OCEANS.1993.326204","DOIUrl":"https://doi.org/10.1109/OCEANS.1993.326204","url":null,"abstract":"Quasi-simultaneous measurements of the ocean wave-radar modulation transfer function (MTF) were performed from the German North Sea Research Platform (FPN) at 1.0 GHz (L-band), 53 GHz (C-band), and 10.0 GHz (X-band) at HH and VV polarization by using one antenna. MTFs obtained at different radar frequencies and polarizations are compared. The results show that the coherence between the radar backscatter and the long ocean wave field is a strongly decreasing function of radar frequency. A residual MTF, M/sub res/ is calculated which is obtained by subtracting the theoretical tilt and range MTFs from the measured total MTF. According to conventional theory, M/sub res/ should be identical to the hydrodynamic MTF and therefore be independent of polarization. However, the experimental data show a strong dependence of the magnitude and phase of M/sub res/ on polarization. The differences between M/sub res/ obtained at HR and VV polarization can partly be explained by a three-scale composite surface model.<<ETX>>","PeriodicalId":130255,"journal":{"name":"Proceedings of OCEANS '93","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115711916","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 : 1993-10-18DOI: 10.1109/OCEANS.1993.326051
S. Gordon, K.R. Griep
Summary form only given. A technique is introduced to select poly-phase codes and design mismatched filters of a pulse compression system to have specific temporal and frequency response characteristics. In the particular problem under study, multiple sonar vehicles, up to eleven, need to be assigned codes and receiver filters that have nearly orthogonal signatures. Also, narrowband users that act as interference are present within the system. A code selection procedure based on global optimization technique called simulated annealing is used that selects codes which have low auto-correlation sidelobes and low cross-correlation peaks. Mismatched filters are designed for these codes which minimize the peak values in the auto-correlation and the cross-correlation. Also, a slight adjustment to the mismatched filter design technique produces mismatched filters with nulls in their frequency response in addition to having low correlation peaks. These two separate procedures, code selection and mismatched filter design, taken together, provide a unique approach to solving the problems of multi-user system corrupted by narrowband interference. The mismatched filter design also allows the design frequency nulls at any frequency with arbitrary null attenuation, null width, and sidelobe level, at the cost of processing gain.<>
{"title":"Systematic search for multi-phase codes and design of mismatched filters for multi-user underwater sonar ranging system","authors":"S. Gordon, K.R. Griep","doi":"10.1109/OCEANS.1993.326051","DOIUrl":"https://doi.org/10.1109/OCEANS.1993.326051","url":null,"abstract":"Summary form only given. A technique is introduced to select poly-phase codes and design mismatched filters of a pulse compression system to have specific temporal and frequency response characteristics. In the particular problem under study, multiple sonar vehicles, up to eleven, need to be assigned codes and receiver filters that have nearly orthogonal signatures. Also, narrowband users that act as interference are present within the system. A code selection procedure based on global optimization technique called simulated annealing is used that selects codes which have low auto-correlation sidelobes and low cross-correlation peaks. Mismatched filters are designed for these codes which minimize the peak values in the auto-correlation and the cross-correlation. Also, a slight adjustment to the mismatched filter design technique produces mismatched filters with nulls in their frequency response in addition to having low correlation peaks. These two separate procedures, code selection and mismatched filter design, taken together, provide a unique approach to solving the problems of multi-user system corrupted by narrowband interference. The mismatched filter design also allows the design frequency nulls at any frequency with arbitrary null attenuation, null width, and sidelobe level, at the cost of processing gain.<<ETX>>","PeriodicalId":130255,"journal":{"name":"Proceedings of OCEANS '93","volume":"165 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116136345","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 : 1993-10-18DOI: 10.1109/OCEANS.1993.326216
A. Tolstoy
Matched field processing (MFP) is a signal processing technique that has only recently been applied to the environmental inverse problem, i.e., to determine the characteristics of an unknown ocean environment. In particular, a 3D tomographic approach has been previously proposed and studied which promises to determine deep water sound-speed profiles as they vary with range, cross-range, and depth. This technique in its most efficient form suggests shot sources (either air or ship deployed) and either multiple vertical arrays, multiple horizontal arrays, or a single array re-deployed several times. This paper discusses work which extends those results to more complicated simulated environments, and also a further generalization of the approach to determine 3D bottom parameters, e.g., sediment sound-speeds and thicknesses.<>
{"title":"Matched field tomographic inversion","authors":"A. Tolstoy","doi":"10.1109/OCEANS.1993.326216","DOIUrl":"https://doi.org/10.1109/OCEANS.1993.326216","url":null,"abstract":"Matched field processing (MFP) is a signal processing technique that has only recently been applied to the environmental inverse problem, i.e., to determine the characteristics of an unknown ocean environment. In particular, a 3D tomographic approach has been previously proposed and studied which promises to determine deep water sound-speed profiles as they vary with range, cross-range, and depth. This technique in its most efficient form suggests shot sources (either air or ship deployed) and either multiple vertical arrays, multiple horizontal arrays, or a single array re-deployed several times. This paper discusses work which extends those results to more complicated simulated environments, and also a further generalization of the approach to determine 3D bottom parameters, e.g., sediment sound-speeds and thicknesses.<<ETX>>","PeriodicalId":130255,"journal":{"name":"Proceedings of OCEANS '93","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114769031","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 : 1993-10-18DOI: 10.1109/OCEANS.1993.326020
A. Ponsford
Development of the Surface Wave Radar test bed at Cape Bonavista, Newfoundland was initiated in 1985. The facility has been used to investigate all aspects of surface wave radar and to provide data for evaluating and developing models of radar performance. Trials have been conducted at the site that demonstrate beyond-the-horizon detection of aircraft to 300 km, surface targets to 500 km, and icebergs to 300 km. The need to predict surface wave radar performance under differing tasks, system parameters and environmental conditions has led to the development of a generalized computer simulation package. An integral part of the development has been the testing and progressive refinement of different components of the simulation package based on experimental results and other advances. The simulation software includes modules that provide estimates of transmission loss, sea clutter, and external noise levels. Of interest in this paper are the sea clutter models and in particular two additional scattering features that are predicted and have been observed to occur outside of the Bragg resonant region. The first of these additional scattering features is referred to as 'off resonance first order clutter' whilst the second is referred to as 'the second-part of second order clutter'. This latter clutter has been predicted to occur when scattering from the ocean occurs from both behind and in front of the transmit point. The scattering mechanism can be visualized as being similar to a repeated first order scatter. Results are presented that illustrate the effect of this scattering mechanism and how it influences the ocean spectrum for surface wave radar.<>
{"title":"A comparison between predicted and measured sea echo Doppler spectra for surface wave radar","authors":"A. Ponsford","doi":"10.1109/OCEANS.1993.326020","DOIUrl":"https://doi.org/10.1109/OCEANS.1993.326020","url":null,"abstract":"Development of the Surface Wave Radar test bed at Cape Bonavista, Newfoundland was initiated in 1985. The facility has been used to investigate all aspects of surface wave radar and to provide data for evaluating and developing models of radar performance. Trials have been conducted at the site that demonstrate beyond-the-horizon detection of aircraft to 300 km, surface targets to 500 km, and icebergs to 300 km. The need to predict surface wave radar performance under differing tasks, system parameters and environmental conditions has led to the development of a generalized computer simulation package. An integral part of the development has been the testing and progressive refinement of different components of the simulation package based on experimental results and other advances. The simulation software includes modules that provide estimates of transmission loss, sea clutter, and external noise levels. Of interest in this paper are the sea clutter models and in particular two additional scattering features that are predicted and have been observed to occur outside of the Bragg resonant region. The first of these additional scattering features is referred to as 'off resonance first order clutter' whilst the second is referred to as 'the second-part of second order clutter'. This latter clutter has been predicted to occur when scattering from the ocean occurs from both behind and in front of the transmit point. The scattering mechanism can be visualized as being similar to a repeated first order scatter. Results are presented that illustrate the effect of this scattering mechanism and how it influences the ocean spectrum for surface wave radar.<<ETX>>","PeriodicalId":130255,"journal":{"name":"Proceedings of OCEANS '93","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126729110","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 : 1993-10-18DOI: 10.1109/OCEANS.1993.325988
Ming Li, D. Farmer
Although freshly spilled oil is buoyant and almost always floats on the surface, the action of water turbulence, and particularly that generated by breaking waves can disintegrate floating oil layers into slicklets, blobs or droplets. The oil droplets can then be entrained into the water column by turbulence and subsurface Langmuir circulations. Small oil droplets having diameters in the range of tens to hundreds /spl mu/m are essentially neutrally-buoyant particles and can be dispersed as deep as Langmuir cells can penetrate. Larger oil droplets with diameters of mm have buoyant rise speeds comparable with the downwelling velocity of Langmuir cells, and they can be suspended in a subsurface retention zone at the downwelling sites. The successful trapping of droplets at the retention zone requires that turbulence be strong enough to pump down the droplets floating on the surface. When Langmuir cells merge with each other, packets of oil droplets collected at the downwelling sites are carried around and redistributed. The Stommel retention zone is not an effective trapping agent when Langmuir cells amalgamate.<>
{"title":"Oil submersion in a wind driven sea","authors":"Ming Li, D. Farmer","doi":"10.1109/OCEANS.1993.325988","DOIUrl":"https://doi.org/10.1109/OCEANS.1993.325988","url":null,"abstract":"Although freshly spilled oil is buoyant and almost always floats on the surface, the action of water turbulence, and particularly that generated by breaking waves can disintegrate floating oil layers into slicklets, blobs or droplets. The oil droplets can then be entrained into the water column by turbulence and subsurface Langmuir circulations. Small oil droplets having diameters in the range of tens to hundreds /spl mu/m are essentially neutrally-buoyant particles and can be dispersed as deep as Langmuir cells can penetrate. Larger oil droplets with diameters of mm have buoyant rise speeds comparable with the downwelling velocity of Langmuir cells, and they can be suspended in a subsurface retention zone at the downwelling sites. The successful trapping of droplets at the retention zone requires that turbulence be strong enough to pump down the droplets floating on the surface. When Langmuir cells merge with each other, packets of oil droplets collected at the downwelling sites are carried around and redistributed. The Stommel retention zone is not an effective trapping agent when Langmuir cells amalgamate.<<ETX>>","PeriodicalId":130255,"journal":{"name":"Proceedings of OCEANS '93","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123686004","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 : 1993-10-18DOI: 10.1109/OCEANS.1993.325995
B. Dushaw, D. Chester, P. Worcester
Reciprocal acoustic transmissions accurately measure the barotropic and, with suitable ray-path geometry, baroclinic components of ocean currents. Tomographically-derived tidal currents agree with both independent measurements and numerical models. Tomographically-derived currents are inherently range averages. Comparison with point measurements, such as from current meters, nonetheless show satisfactory agreement in all cases. Tomographically-derived, areal-averaged relative vorticity is unique and difficult to verify, but in both the Florida Straits and Gulf Stream regions tomographic vorticity estimates are consistent with current-meter-derived vorticity estimates.<>
{"title":"A review of ocean current and vorticity measurements using long-range reciprocal acoustic transmissions","authors":"B. Dushaw, D. Chester, P. Worcester","doi":"10.1109/OCEANS.1993.325995","DOIUrl":"https://doi.org/10.1109/OCEANS.1993.325995","url":null,"abstract":"Reciprocal acoustic transmissions accurately measure the barotropic and, with suitable ray-path geometry, baroclinic components of ocean currents. Tomographically-derived tidal currents agree with both independent measurements and numerical models. Tomographically-derived currents are inherently range averages. Comparison with point measurements, such as from current meters, nonetheless show satisfactory agreement in all cases. Tomographically-derived, areal-averaged relative vorticity is unique and difficult to verify, but in both the Florida Straits and Gulf Stream regions tomographic vorticity estimates are consistent with current-meter-derived vorticity estimates.<<ETX>>","PeriodicalId":130255,"journal":{"name":"Proceedings of OCEANS '93","volume":"94 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123779043","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 : 1993-10-18DOI: 10.1109/OCEANS.1993.326205
L. Zurk, W. Plant
Spectra of SAR images of the ocean have been simulated using quasilinear, velocity-bunching, and full time-dependent modelling. These simulations have been compared with X, C, and L-band imagery collected during the SAXON-FPN experiment using parameter values measured from the research tower, FPN, during the experiment. The results indicate that in most cases the three models agree well with each other and with actual imagery within the domain of applicability of each model. This is to be expected since the various models are simply different approximations to the full SAR imaging theory. The authors show that a coherence time approximation is not adequate to explain the azimuthal roll-off observed in SAR image spectra at all altitudes. They also find shifts of the spectral peak of azimuthally-travelling waves in both the simulations and images compared to measured buoy spectra; these can be understood in terms of the imaging mechanism. Finally, they find that the phase of the MTF measured on the tower cannot explain the observed artificial tilt of spectra of range-travelling waves, in agreement with the results of Bruning et al. 1993.<>
利用拟线性、速度聚束和完全依赖时间的模型模拟了海洋SAR图像的光谱。这些模拟与SAXON-FPN实验期间收集的X、C和l波段图像进行了比较，并使用了实验期间从研究塔FPN测量的参数值。结果表明，在大多数情况下，三种模型在各自的适用范围内都能很好地吻合实际图像。这是可以预料到的，因为各种模型只是对完整的SAR成像理论的不同近似。作者指出，相干时间近似不足以解释在所有高度的SAR图像光谱中观测到的方位滚降。他们还发现，与实测浮标光谱相比，模拟和图像中的方位行波光谱峰都发生了移位;这些可以从成像机制的角度来理解。最后，他们发现在塔上测量的MTF相位不能解释观测到的距离行波光谱的人为倾斜，这与Bruning et al. 1993的结果一致。
{"title":"Simulations of SAR imagery of the ocean compared with data","authors":"L. Zurk, W. Plant","doi":"10.1109/OCEANS.1993.326205","DOIUrl":"https://doi.org/10.1109/OCEANS.1993.326205","url":null,"abstract":"Spectra of SAR images of the ocean have been simulated using quasilinear, velocity-bunching, and full time-dependent modelling. These simulations have been compared with X, C, and L-band imagery collected during the SAXON-FPN experiment using parameter values measured from the research tower, FPN, during the experiment. The results indicate that in most cases the three models agree well with each other and with actual imagery within the domain of applicability of each model. This is to be expected since the various models are simply different approximations to the full SAR imaging theory. The authors show that a coherence time approximation is not adequate to explain the azimuthal roll-off observed in SAR image spectra at all altitudes. They also find shifts of the spectral peak of azimuthally-travelling waves in both the simulations and images compared to measured buoy spectra; these can be understood in terms of the imaging mechanism. Finally, they find that the phase of the MTF measured on the tower cannot explain the observed artificial tilt of spectra of range-travelling waves, in agreement with the results of Bruning et al. 1993.<<ETX>>","PeriodicalId":130255,"journal":{"name":"Proceedings of OCEANS '93","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121764699","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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