Velocity measuring correlation sonar

Dickey, Frank R.

doi:10.1121/1.386867

Cited by 5 publications

(10 citation statements)

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“…• SAS micronavigation as input to an INS: SAS micronavigation by estimating both the sway and the surge motion was first described in 1978 (Dickey, 1981) and was demonstrated in 2001 (Wang et al, 2001). After development by FFI and industrialization by KM, the collaboration achieved SAS micronavigation aiding with an accuracy that surpassed that of the state of the art DVLs (Kongsberg, 2019), with the first system delivered late in 2020 with the HUGIN Superior AUV.…”

Section: Spatial Coherence Of Speckle Backgroundmentioning

confidence: 99%

Wideband Interferometry in Synthetic Aperture Sonar

Sæbø

Synnes

Hansen

2013

IEEE Trans. Geosci. Remote Sensing

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is a principal scientist at FFI, while Andreas Austeng is a professor at UiO. I am employed at FFI, where I started in 1998 after receiving my degree of Cand. Scient. in Physics from the University of Bergen. The work on the thesis was conducted as a part of my job over the years 2011 -2021, and was funded by FFI's projects on synthetic aperture sonar (SAS). These SAS projects have been run and financed through a collaboration between FFI, Kongsberg Maritime and the Royal Norwegian Navy. This thesis includes a collection of five papers, placed and presented in a larger common perspective. I first place the title topic of "Advanced SAS" in a greater context. Then I present each of the individual papers, and give an updated review on their topics. I follow up with a discussion on my contributions in a greater perspective, before I summarize my findings and conclude.

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Section: Spatial Coherence Of Speckle Backgroundmentioning

confidence: 99%

Wideband Interferometry in Synthetic Aperture Sonar

Sæbø

Synnes

Hansen

2013

IEEE Trans. Geosci. Remote Sensing

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“…SAS micronavigation is based on recognizing the speckle pattern between time series of acoustic backscatter. Using a SAS system with a multielement receiver array, element data of partially overlapping array positions from consecutive pings are crosscorrelated in a search for the element pair and relative time delay with the highest degree of coherence, and the corresponding arguments give the along-track displacement and slant-range displacements [17], [22], [23].…”

Section: A Repeat-pass Sas Micronavigationmentioning

confidence: 99%

“…The decorrelation with along-track baseline is used for motion estimation in correlation sonar, including SAS micronavigation. Accurate knowledge of its functional form is crucial for acquiring navigation estimates of high accuracy and low bias [17], [22], [23], [30,Ch. 5], [31].…”

Section: B Spatial Coherencementioning

confidence: 99%

“…Element data from different pings, recorded at roughly the same position, can be correlated to provide navigation updates. Overlapping phase centers will have the highest coherence, and give the along track displacement, while the relative change in round trip time gives the slant-range displacement [17], [22], [23]. The accuracy of the estimates follows from the degree of coherence and the system parameters [17].…”

Section: Sas Micronavigationmentioning

confidence: 99%

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Spatial Coherence of Speckle for Repeat-Pass Synthetic Aperture Sonar Micronavigation

Synnes

Hansen

Sæbø

2021

IEEE J. Oceanic Eng.

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Accurate positioning of autonomous underwater vehicles is a major challenge. The long-term drift is problematic if global position updates are not available, and for applications such as repeat-pass interferometry and coherent change detection, millimeter accuracy is needed. Repeat-pass synthetic aperture sonar (SAS) micronavigation is one potential technique for countering both challenges. While single-pass SAS micronavigation enabled successful coherent processing within one track, the potential is that repeat-pass SAS micronavigation can support coherent processing between passes. Both techniques are based on recognizing the speckle pattern in the seafloor return, but repeat-pass SAS micronavigation has additional challenges with the larger temporal and spatial separations between the observations. In this study, we investigate the spatial correlation of speckle as observed from SAS systems. We divide the different contributions to spatial decorrelation into three groups: 1) speckle decorrelation; 2) footprint mismatch; and 3) stretching. We examine each contribution separately and develop simplified formulas for their decorrelation baselines. When correlating synthetic aperture images, decorrelation from stretching dominates. When correlating single-element data recorded at low grazing angles common to SAS, speckle decorrelation dominates. We validate our findings on experimental data, and by combining elements into larger effective elements, we demonstrate increasing the across-track baseline for repeatpass SAS micronavigation updates from less than 1 to 10 m.

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“…For navigation, no single technique provides a broadly applicable solution for small, long-range AUVs. A variety of technologies exist today, including radio and satellite systems, long, short and ultrashort baseline acoustic systems (Abbott, 1978;Elliot and Olson, 1984;Jacobsen et al, 1985), acoustic doppler and correlation speed logs (Sternick, 1978;Dickey and Edward, 1978), inertial systems (Johnstone and Fries, 1988) and terrain-following techniques (Stasior, 1991: Tuohy et al, 1993. Radio and satellite navigation requires that the vehicle be at or close to the surface, long baseline acoustic navigation accuracy degrades dramatically at longer ranges, and inertial systems have relatively high error levels for slow-moving AUVs.…”

Section: Acoustic Telemetry and Navigationmentioning

confidence: 99%