1. A towable spread for surveying a water-submerged surface with a single towing vessel comprising at least two laterally spaced submarine vehicles of which at least one is dirigible, tow cables of substantially equal lengths attached to said vehicles, means operable under towing conditions to cause said vehicles to seek and maintain a preselected constant distance above the surface being surveyed, power means carried by the dirigible vehicle for steering the course of said dirigible vehicle, distance sensing means for deriving a signal corresponding to the lateral separation of the two vehicles, and means responsive to the departure of said derived signal from a preselected value for developing a corresponding control signal for said power means.
A system for surveying an underwater topography includes an ultrasonic sensor array disposable in physical contact with a body of water for generating electrical signals encoding ultrasonic echo responses of underwater objects in the body of water. The sensor array includes a plurality of electromechanical transducers in turn including at least one electroacoustic transducer and one acoustoelectric transducer. The transducers are disposed in a configuration extending in at least two dimensions. An a-c current generator is operatively connected to the electroacoustic transducer for energizing the electroacoustic transducer with an electrical signal of a pre-established ultrasonic frequency. Means are provided which operatively connected to the sensor array for determining locations of the electromechanical transducers relative to one another. A processor or computer is operatively connected to the sensor array for analyzing the electrical signals in accordance with the determined locations of the electromechanical transducers to determine surfaces of objects disposed at least partially in the body of water and for generating a video signal encoding an image of the objects. A video monitor is operatively connected to the processing means for displaying the image of the objects.
The invention relates to a module (100) which is attached to a trawl, and which at least comprises measuring sensors (330) and a power supply unit. (320) The sensors are basically inactive, but can be activated as the need arises to measure different parameters. In an embodiment the module also includes a power-generating movement device connected to a charging device that can supply energy to the power supply unit. The module may also include communication means. In an alternative embodiment the module ma include a trawl door that can drag the drawl in a desired direction. Several modules may be (combined to form a system that both measures different parameters and positions the trawl in order to achieve an optimal trawling process.
A system for surveying an underwater topography includes an ultrasonic sensor array disposable in physical contact with a body of water for generating electrical signals encoding ultrasonic echo responses of underwater objects in the body of water. The sensor array includes a plurality of electromechanical transducers in turn including at least one electroacoustic transducer and one acoustoelectric transducer. The transducers are disposed in a configuration extending in at least two dimensions. An a-c current generator is operatively connected to the electroacoustic transducer for energizing the electroacoustic transducer with an electrical signal of a pre-established ultrasonic frequency. Means are provided which operatively connected to the sensor array for determining locations of the electromechanical transducers relative to one another. A processor or computer is operatively connected to the sensor array for analyzing the electrical signals in accordance with the determined locations of the electromechanical transducers to determine surfaces of objects disposed at least partially in the body of water and for generating a video signal encoding an image of the objects. A video monitor is operatively connected to the processing means for displaying the image of the objects.
A bistatic system and method is disclosed for mapping a large swath of the ocean bottom on a single sweep using two survey ships traveling approximately side-by-side some distance apart on parallel courses. Each ship transmits a fan shaped sonic pulse or ping symmetrically downward about the vertical and transverse to the ship's longitudinal axis and processes the backscattered echo for depth. The forward scattered portion of this pulse or a second sonic pulse transmitted downward at an angle between the ships toward the other ship is received by the other ship and is analyzed to determine ocean bottom depths of the swath between the ships. The analyzed width of an insonified swath portion is sufficiently wide so as to overlap, at an edge, with an edge of each adjacent insonified swath portion analyzed. This partial redundancy provides a means for continuous calibration by comparing depth determinations for consistency and accuracy. Precise global navigational fixes and relative intership positional fixes are to be provided by the satellite Global Positioning System (GPS) as well as other navigational systems.
A novel configuration of a low-frequency lightweight sonar system is described comprising a coaxial assembly of a transmitting transducer and a directional receiving array contained within a cigar-shaped streamlined cylindrical housing less than 1 ft. diameter which operates in the 3 to 4 kHz frequency region and achieves submarine target detection ranges in the order of 20,000 meters with a bearing accuracy within 2.degree.. The small cylindrical streamlined structural assembly results in a very great reduction in drag resistance while it is being towed underwater at high speeds as compared to conventional sonar domes which must be an order of magnitude larger in diameter to accommodate the larger conventional scanning sonar transducers which are several wavelengths in diameter at the operating frequency. The enormous reduction in drag resistance and the novel method of deployment permits the described low-frequency lightweight sonar system assembly to be pulled through the water at very high speeds by small patrol craft or helicopters to achieve very effective long-range low-cost high-speed sonar surveillance of very large areas of the sea.
