Pub Date : 2010-05-24DOI: 10.1109/OCEANSSYD.2010.5603819
N. Nowsheen, C. Benson, M. Frater
Contemporary underwater acoustic networks use low frequency modems. While these modems can provide long range communication, their low operating frequencies mean that only low channel bandwidth is available, which results in slow data rates. This motivates our development of a high frequency modem which offers the potential for large channel bandwidth, and hence greater link capacity. There is a range-frequency trade-off because absorption becomes very high at high frequency. Our intended operating frequencies from 100 kHz to 1 MHz would only support link ranges perhaps from 1 km down to under 100m, with communication ranges longer than this requiring forwarding over a network. Reconfigurable computing based Field Programmable Gate Arrays (FPGAs) are used to accelerate product development and support evolution of fielded systems. Given the immaturity of the field of underwater communication, a reconfigurable modem is a valuable tool for development and testing modem techniques. We present a design idea to implement an acoustic modem solely in FPGA, whereas most existing modems are implemented as a combination of FPGA and DSP processors. Aside from simple anti-aliasing filters, which could be incorporated in the preamplifier stage, the modem does all of its processing in the digital domain - maximising flexibility. In this work, we describe the initial design and architecture of our software based acoustic modem that avoids the monetary cost or time investment required to design a commercial modem or custom hardware for many applications. Our demodulator is implemented using a Costas loop which performs both suppressed carrier reconstruction and synchronous data detection within the loop. Results from initial implementation are also reported in this paper.
{"title":"Design of a high frequency FPGA acoustic modem for underwater communication","authors":"N. Nowsheen, C. Benson, M. Frater","doi":"10.1109/OCEANSSYD.2010.5603819","DOIUrl":"https://doi.org/10.1109/OCEANSSYD.2010.5603819","url":null,"abstract":"Contemporary underwater acoustic networks use low frequency modems. While these modems can provide long range communication, their low operating frequencies mean that only low channel bandwidth is available, which results in slow data rates. This motivates our development of a high frequency modem which offers the potential for large channel bandwidth, and hence greater link capacity. There is a range-frequency trade-off because absorption becomes very high at high frequency. Our intended operating frequencies from 100 kHz to 1 MHz would only support link ranges perhaps from 1 km down to under 100m, with communication ranges longer than this requiring forwarding over a network. Reconfigurable computing based Field Programmable Gate Arrays (FPGAs) are used to accelerate product development and support evolution of fielded systems. Given the immaturity of the field of underwater communication, a reconfigurable modem is a valuable tool for development and testing modem techniques. We present a design idea to implement an acoustic modem solely in FPGA, whereas most existing modems are implemented as a combination of FPGA and DSP processors. Aside from simple anti-aliasing filters, which could be incorporated in the preamplifier stage, the modem does all of its processing in the digital domain - maximising flexibility. In this work, we describe the initial design and architecture of our software based acoustic modem that avoids the monetary cost or time investment required to design a commercial modem or custom hardware for many applications. Our demodulator is implemented using a Costas loop which performs both suppressed carrier reconstruction and synchronous data detection within the loop. Results from initial implementation are also reported in this paper.","PeriodicalId":129808,"journal":{"name":"OCEANS'10 IEEE SYDNEY","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134294335","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 : 2010-05-24DOI: 10.1109/OCEANSSYD.2010.5603859
Tjasa Boh, J. Billingsley, R. Bradbeer, P. Hodgson
The Bekker Theory of Locomotion has long been the leading applied theory when it comes to calculating and predicting soil-tyre interaction for terrestrial wheeled and tracked vehicles. Whilst the theory is applicable for terrestrial systems, there is no evidence to suggest it also applies under water. Furthermore, the complications of measuring the required soil parameters in marine substratum makes it difficult to apply. This paper explores the slip-based approach to the Bekker theorem and suggests an experiment designed to validate this theorem for underwater applications.
{"title":"Terramechanics based traction control of underwater wheeled robot","authors":"Tjasa Boh, J. Billingsley, R. Bradbeer, P. Hodgson","doi":"10.1109/OCEANSSYD.2010.5603859","DOIUrl":"https://doi.org/10.1109/OCEANSSYD.2010.5603859","url":null,"abstract":"The Bekker Theory of Locomotion has long been the leading applied theory when it comes to calculating and predicting soil-tyre interaction for terrestrial wheeled and tracked vehicles. Whilst the theory is applicable for terrestrial systems, there is no evidence to suggest it also applies under water. Furthermore, the complications of measuring the required soil parameters in marine substratum makes it difficult to apply. This paper explores the slip-based approach to the Bekker theorem and suggests an experiment designed to validate this theorem for underwater applications.","PeriodicalId":129808,"journal":{"name":"OCEANS'10 IEEE SYDNEY","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134269096","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 : 2010-05-24DOI: 10.1109/OCEANSSYD.2010.5603512
T. Horiuchi, F. Wolk, P. Macoun
The stability of the conductivity sensor is a key consideration for the long-term deployments of the instruments on mooring and observatories, because the conductivity measurement is very sensitive to the accumulation of organisms (bio-fouling) inside the sensor. We tested the performance of a conductivity sensor, the ALEC CTW, which features a simple but effective wiper mechanism to keep the sensing cavity of the conductivity cell free of bio-fouling. The sensor was deployed for a period of 12 months on the Victoria Experimental Network Under the Sea (VENUS) observatory, operated by the University of Victoria in British Columbia, Canada. The VENUS observatory provided power and data telemetry to monitor the sensor's performance in real time. A post recovery calibration of the conductivity sensor showed that the wiper mechanism was effective in maintaining the sensors calibration.
{"title":"Long-term stability of a new conductivity-temperature sensor tested on the VENUS cabled observatory","authors":"T. Horiuchi, F. Wolk, P. Macoun","doi":"10.1109/OCEANSSYD.2010.5603512","DOIUrl":"https://doi.org/10.1109/OCEANSSYD.2010.5603512","url":null,"abstract":"The stability of the conductivity sensor is a key consideration for the long-term deployments of the instruments on mooring and observatories, because the conductivity measurement is very sensitive to the accumulation of organisms (bio-fouling) inside the sensor. We tested the performance of a conductivity sensor, the ALEC CTW, which features a simple but effective wiper mechanism to keep the sensing cavity of the conductivity cell free of bio-fouling. The sensor was deployed for a period of 12 months on the Victoria Experimental Network Under the Sea (VENUS) observatory, operated by the University of Victoria in British Columbia, Canada. The VENUS observatory provided power and data telemetry to monitor the sensor's performance in real time. A post recovery calibration of the conductivity sensor showed that the wiper mechanism was effective in maintaining the sensors calibration.","PeriodicalId":129808,"journal":{"name":"OCEANS'10 IEEE SYDNEY","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130311660","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 : 2010-05-24DOI: 10.1109/OCEANSSYD.2010.5603631
A. Blomberg, M. Hayes
In this paper we consider adaptive beamforming techniques to suppress the dominant multipath for a multielement interferometric synthetic aperture sonar. We use a broadband variant of the minimum variance (MV) beamformer and apply it to reconstruct bathymetry using data from the KiwiSAS-4 sonar. This has three vertically displaced hydrophone arrays. The MV beamformer is used to estimate the angle of arrival of the backscattered echo from the sea floor, and from that the height of the sea floor. The conventional delay-and-sum (DAS) beamformer is used for comparison.
{"title":"Multipath reduction for bathymetry using adaptive beamforming","authors":"A. Blomberg, M. Hayes","doi":"10.1109/OCEANSSYD.2010.5603631","DOIUrl":"https://doi.org/10.1109/OCEANSSYD.2010.5603631","url":null,"abstract":"In this paper we consider adaptive beamforming techniques to suppress the dominant multipath for a multielement interferometric synthetic aperture sonar. We use a broadband variant of the minimum variance (MV) beamformer and apply it to reconstruct bathymetry using data from the KiwiSAS-4 sonar. This has three vertically displaced hydrophone arrays. The MV beamformer is used to estimate the angle of arrival of the backscattered echo from the sea floor, and from that the height of the sea floor. The conventional delay-and-sum (DAS) beamformer is used for comparison.","PeriodicalId":129808,"journal":{"name":"OCEANS'10 IEEE SYDNEY","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122882356","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 : 2010-05-24DOI: 10.1109/OCEANSSYD.2010.5603573
Ji Daxiong, Liu Jian, Liu Kaizhou
A calibration problem for log sensor of UUV is established and the problem can be divided into two separate parts: misalignment angle and scale factor of log sensor. Instead of using the conventional least square algorithm, a fine calibration approach based on M-estimate is used to suppress the effect of non-white noise. The adaptive factor relation to calibration precision is brought forward which is different from usual forgetting factor. The feasibility of the approach is demonstrated in the test of sea trail.
{"title":"Log sensor calibration using M-estimate","authors":"Ji Daxiong, Liu Jian, Liu Kaizhou","doi":"10.1109/OCEANSSYD.2010.5603573","DOIUrl":"https://doi.org/10.1109/OCEANSSYD.2010.5603573","url":null,"abstract":"A calibration problem for log sensor of UUV is established and the problem can be divided into two separate parts: misalignment angle and scale factor of log sensor. Instead of using the conventional least square algorithm, a fine calibration approach based on M-estimate is used to suppress the effect of non-white noise. The adaptive factor relation to calibration precision is brought forward which is different from usual forgetting factor. The feasibility of the approach is demonstrated in the test of sea trail.","PeriodicalId":129808,"journal":{"name":"OCEANS'10 IEEE SYDNEY","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131949842","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 : 2010-05-24DOI: 10.1109/OCEANSSYD.2010.5603610
M. Ueno, Y. Tsukada, H. Sawada
The submersible surface ship (SSS) is a ship that can avoid rough seas by going underwater. In order to submerge the SSS uses wings producing downward lift. The SSS, in submerged condition, keeps residual buoyancy for its safety. A prototype of SSS of which configuration is a hull, a pair of main wings and a pair of horizontal tail wings is designed and its model ship for tank tests is made. The circular motion test was carried out and hydrodynamic forces and moment in vertical motion were measured. The effect of submerged depth on the resistance and wings performances, and the effect of attack angle and pitch rate on the longitudinal and vertical forces and pitch moment acting on the SSS model are clarified. A method to estimate linear hydrodynamic derivatives is applied to the SSS model and compared with the results of tank test data analysis. The validity of the method and test data together with its effective utilization is discussed.
{"title":"Hydrodynamic forces and moment acting on a submersible surface ship in vertical motion","authors":"M. Ueno, Y. Tsukada, H. Sawada","doi":"10.1109/OCEANSSYD.2010.5603610","DOIUrl":"https://doi.org/10.1109/OCEANSSYD.2010.5603610","url":null,"abstract":"The submersible surface ship (SSS) is a ship that can avoid rough seas by going underwater. In order to submerge the SSS uses wings producing downward lift. The SSS, in submerged condition, keeps residual buoyancy for its safety. A prototype of SSS of which configuration is a hull, a pair of main wings and a pair of horizontal tail wings is designed and its model ship for tank tests is made. The circular motion test was carried out and hydrodynamic forces and moment in vertical motion were measured. The effect of submerged depth on the resistance and wings performances, and the effect of attack angle and pitch rate on the longitudinal and vertical forces and pitch moment acting on the SSS model are clarified. A method to estimate linear hydrodynamic derivatives is applied to the SSS model and compared with the results of tank test data analysis. The validity of the method and test data together with its effective utilization is discussed.","PeriodicalId":129808,"journal":{"name":"OCEANS'10 IEEE SYDNEY","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132173187","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 : 2010-05-24DOI: 10.1109/OCEANSSYD.2010.5603942
S. Anderson, J.T. Morris
Collisions between ships and whales are not rare occurrences. Apart from constituting a major cause of death for whale species which frequent busy oceanic areas such as the North Atlantic, such collisions often result in damage to ships. Thus there is keen interest in finding reliable means of detection of whales at sufficient range to ensure successful collision avoidance. In this paper we present the results of experiments aimed at establishing the potential of polarimetric microwave radar to provide such a means. The key element in our approach is the construction of a polarimetric filter which enhances the contrast between the disturbed sea surface around the whale and the ambient sea. The results suggest that detection can be achieved under conditions where conventional uni-polar radars such as those normally found on merchant ships would fail.
{"title":"On the detection of marine mammals with ship-borne polarimetric microwave radar","authors":"S. Anderson, J.T. Morris","doi":"10.1109/OCEANSSYD.2010.5603942","DOIUrl":"https://doi.org/10.1109/OCEANSSYD.2010.5603942","url":null,"abstract":"Collisions between ships and whales are not rare occurrences. Apart from constituting a major cause of death for whale species which frequent busy oceanic areas such as the North Atlantic, such collisions often result in damage to ships. Thus there is keen interest in finding reliable means of detection of whales at sufficient range to ensure successful collision avoidance. In this paper we present the results of experiments aimed at establishing the potential of polarimetric microwave radar to provide such a means. The key element in our approach is the construction of a polarimetric filter which enhances the contrast between the disturbed sea surface around the whale and the ambient sea. The results suggest that detection can be achieved under conditions where conventional uni-polar radars such as those normally found on merchant ships would fail.","PeriodicalId":129808,"journal":{"name":"OCEANS'10 IEEE SYDNEY","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133358912","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 : 2010-05-24DOI: 10.1109/OCEANSSYD.2010.5603541
Tomoya Inoue, K. Takagi, T. Shiosawa
Flipper type crawler system gives advantages when running on the irregular seafloor and when working on the seafloor. We developed a small size ROV (remotely operated vehicle) equipped with the flipper type crawler systems and conducted the experiments using it in a water tank and on the seafloor to observe its advantages. In the experiments in the water tank, the ROV was tested to run on the tilting table changing an angle and also to run over bumps nailed onto the top board of the tilting table. In the experiments on the seafloor, the ROV could evacuate from the condition that the crawler system was slightly submerged in the sand. Also the ROV could run and climb up the bumps. This paper describes the developed flipper type crawler systems and its advantages by describing the results of the experiments in the water tank and on the seafloor.
{"title":"Flipper type crawler system for running on the irregular seafloor","authors":"Tomoya Inoue, K. Takagi, T. Shiosawa","doi":"10.1109/OCEANSSYD.2010.5603541","DOIUrl":"https://doi.org/10.1109/OCEANSSYD.2010.5603541","url":null,"abstract":"Flipper type crawler system gives advantages when running on the irregular seafloor and when working on the seafloor. We developed a small size ROV (remotely operated vehicle) equipped with the flipper type crawler systems and conducted the experiments using it in a water tank and on the seafloor to observe its advantages. In the experiments in the water tank, the ROV was tested to run on the tilting table changing an angle and also to run over bumps nailed onto the top board of the tilting table. In the experiments on the seafloor, the ROV could evacuate from the condition that the crawler system was slightly submerged in the sand. Also the ROV could run and climb up the bumps. This paper describes the developed flipper type crawler systems and its advantages by describing the results of the experiments in the water tank and on the seafloor.","PeriodicalId":129808,"journal":{"name":"OCEANS'10 IEEE SYDNEY","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132637262","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 : 2010-05-24DOI: 10.1109/OCEANSSYD.2010.5603879
A. Kerans, A. Kulessa, G. Woods, A. Clark
This paper presents the culmination of ten years of research into propagation inside the tropical maritime evaporation duct. The results of this research are used to develop a theoretical path design for an over ocean microwave radio system and this design is compared with results from an actual deployed system.
{"title":"A theoretical path design for long range over ocean microwave","authors":"A. Kerans, A. Kulessa, G. Woods, A. Clark","doi":"10.1109/OCEANSSYD.2010.5603879","DOIUrl":"https://doi.org/10.1109/OCEANSSYD.2010.5603879","url":null,"abstract":"This paper presents the culmination of ten years of research into propagation inside the tropical maritime evaporation duct. The results of this research are used to develop a theoretical path design for an over ocean microwave radio system and this design is compared with results from an actual deployed system.","PeriodicalId":129808,"journal":{"name":"OCEANS'10 IEEE SYDNEY","volume":"116 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117239315","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 : 2010-05-24DOI: 10.1109/oceanssyd.2010.5603807
M. Isakson, N. Chotiros
Much of the littoral region of Southern and Western Australia is composed of a soft limestone bed covered by a layer of unconsolidated sand [2]. The limestone bed, composed of calcarenite, has a high shear wave speed and there is often efficient coupling between the water born wave and the shear mode. Although studies of the effect of the elastic mode in the calcarenite on transmission loss have been undertaken, the effects of the thin sand layer and interface roughness must be quantified in order to determine a robust inversion scheme. It is found that a 1.0 m sand layer decreases the transmission loss by more than 5 dB while a 2.5 m layer can decrease the loss by as much as 20 dB. Interface roughness affects higher frequencies by increasing transmission loss and a rough interface waveguide with a sand layer can have a similar level of transmission loss as a waveguide with a bare calcarenite bottom. However, the frequency dependence and model interference patterns of the two waveguides are different. An inversion scheme based on a bare calcarenite model which would lead incorrect results.
{"title":"A finite element model of propagation on the Southern and Western Australian continental shelf","authors":"M. Isakson, N. Chotiros","doi":"10.1109/oceanssyd.2010.5603807","DOIUrl":"https://doi.org/10.1109/oceanssyd.2010.5603807","url":null,"abstract":"Much of the littoral region of Southern and Western Australia is composed of a soft limestone bed covered by a layer of unconsolidated sand [2]. The limestone bed, composed of calcarenite, has a high shear wave speed and there is often efficient coupling between the water born wave and the shear mode. Although studies of the effect of the elastic mode in the calcarenite on transmission loss have been undertaken, the effects of the thin sand layer and interface roughness must be quantified in order to determine a robust inversion scheme. It is found that a 1.0 m sand layer decreases the transmission loss by more than 5 dB while a 2.5 m layer can decrease the loss by as much as 20 dB. Interface roughness affects higher frequencies by increasing transmission loss and a rough interface waveguide with a sand layer can have a similar level of transmission loss as a waveguide with a bare calcarenite bottom. However, the frequency dependence and model interference patterns of the two waveguides are different. An inversion scheme based on a bare calcarenite model which would lead incorrect results.","PeriodicalId":129808,"journal":{"name":"OCEANS'10 IEEE SYDNEY","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117283034","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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