System and method for accurate positioning of control devices for instrumented cables
AssigneeKongsberg Seatex AS
InventorsOla Erik Fjellstad, Per Christian Berntsen
Life of this patent
Estimating the term…
Abstract
Method and system for high-accurate position determination of control devices arranged in connection with instrumented cables towed behind a survey vessel by at least one autonomous surface vessel provided with acoustic communication means, where the control devices are provided with acoustic elements, and where the acoustic communication means and acoustic elements are used for accurate positioning of the surface vessel above the control device.
Claims21
A method for high-accurate position determination of a control devices (20a,b) in connection with instrumented cables being towed behind a survey vessel via at least one surface vessel (40) provided with two or more acoustic communication means (43) that form known angles with each other, where the control devices (20a,b) are provided with acoustic elements (21), comprising the steps of:
- positioning at least one surface vessel (40) in the vicinity of a chosen control device (20a,b) arranged in connection with an instrumented cable via control commands from the survey vessel,
- transmitting directive modulated acoustic signals from one or both of the acoustic elements (21) in the control device (20a,b) and the two or more acoustic communication means (43) of the surface vessel(s) (40), and the directive modulated acoustic signals are transmitted with at least two different frequencies (f1, f2) in two different directions, and
- using the two or more acoustic communication means (43) in the surface vessel (40), the acoustic elements in the control device (20a,b), and the relative strength between the measured directive modulated signals to position the surface vessel (40) accurately above the chosen control device (20a,b).
A system for high-accurate position determination of control devices (20a,b) arranged in connection with instrumented cables towed behind a survey vessel via at least one autonomous surface vessel (40) provided with two or more acoustic communication means (43) that form known angles with each other, where the control devices (20a,b) are provided with acoustic elements (21), wherein the two or more acoustic communication means (43) of the surface vessel (40) and the acoustic elements (21) of the control devices (20a,b) are arranged for direct communication with each other for positioning the surface vessel (40) in accurate position over a chosen control device, the acoustic communication elements (21) are arranged to transmit directive modulated signals with different frequencies (f1, f2, f3) in different directions, and the control unit (44) is arranged for positioning the autonomous surface vessel (40) in accurate position above a control device (20a,b) of interest based on the relative strength between the measured directive acoustic modulated signals.
Dependencies are inferred from the claim text.