Patent ID: 9678205
Date: 2017-06-13
CPC Classifications: G01S

Claim:
1. A method for determining at least one motion characteristic in terms of position, speed and/or course of at least one marine vessel that moves in waters relative to fixed or floating radar signal reflective areas, locations or installations, said vessel transmitting at least one rotational sweeping radar signal in the horizontal plane and which in relation to known positions causes the determination of said at least one motion characteristic, wherein the method comprises: a) providing at least three detectors communicating with a signal processing unit and detecting said radar signal using the at least three detectors placed at defined, known positions in said areas, locations or installations successively receiving the sweeping radar signal, b) establishing, with the signal processing unit, successive signal vectors between the vessel and respective positions of the detectors as the radar signal, by its rotational sweep, successively hits the respective ones of the detectors, c) at the signal processing unit, calculating angles between the successive signal vectors as a function of time intervals between signals which are detected as the radar signal beam hits the respective detectors in repeated cycles, d) at the signal processing unit, calculating on the basis of estimated signal vector angles at a common intersection point for the signal vectors to determine the position of the vessel, e) on the basis of repeated cycles of the radar signal beam rotation sweep repeating the steps a)-d), the signal processing unit determines incremental position changes to determine the speed, course and patterns of movement of the vessel, f) in the signal processing in steps a)-e), using the radar signals received from the detectors and originating from the vessel, there is a continuous selection of optimal combinations of said time intervals as a function of mutual geometric relations between the vessel and the respective positions of the detectors, wherein the selection takes place as a function of one or more of: angular distribution between the signal vectors, mutual spacing between signal vectors, signal quality of the received signals and the signal strength of the received signals, g) at the signal processing unit, comparing the vessel position, speed and/or course with acceptable limit values relative to fixed or moving obstacles in the waters where the vessel is located, and h) initiating, at the signal processing unit, alert functions, if the vessel movements exceed these limit values or if the radar signals from the vessel cease, said alert functions comprising a notification to at least one of an authority, a surveillance unit, and one or more of the vessels if such movable obstacles in the form of said vessels are in danger of colliding with each other or at least one of the vessels is in danger of colliding with other obstacles.