Abstract 1. A catacoustic system for detecting the intrusion of a body in an object field under a water surface at a harbor entrance or the like comprising a high resolution sonar apparatus including a submerged transducer having a vertically oriented fan shape directivity pattern directed at an object field athwart the harbor entrance and having its principal axis slanted towards the water surface, means for periodically pulsing said transducer to radiate pulses, a display medium, and means for receiving flutter echoes of each pulse returned from the water surface and for producing markings at points along a line on said medium varying in position in accord with the range from which said echoes are received, the markings for echoes from successive pulses being produced in line by line correlation, whereby a significant change in the display with time indicates the position of a body intruding in said object field.
A catacoustic system for detecting the intrusion of a body in an object field under a water surface at a harbor entrance or the like comprising a high resolution sonar apParatus including a submerged transducer having a vertically oriented fan shape directivity pattern directed at an object field athwart the harbor entrance and having its principal axis slanted towards the water surface, means for periodically pulsing said transducer to radiate pulses, a display medium, and means for receiving flutter echoes of each pulse returned from the water surface and for producing markings at points along a line on said medium varying in position in accord with the range from which said echoes are received, the markings for echoes from successive pulses being produced in line by line correlation, whereby a significant change in the display with time indicates the position of a body intruding in said object field.
Claim 2
Dependent Claim
148 words
A catacoustic system for detecting the intrusion of a body in an object field under a water surface at a harbor entrance or the like comprising a high resolution sonar apParatus including a submerged transducer having a vertically oriented fan shape directivity pattern directed at an object field athwart the harbor entrance and having its principal axis slanted towards the water surface, means for periodically pulsing said transducer to radiate pulses, a display medium, and means for receiving flutter echoes of each pulse returned from the water surface and for producing markings at points along a line on said medium varying in position in accord with the range from which said echoes are received, the markings for echoes from successive pulses being produced in line by line correlation, whereby a significant change in the display with time indicates the position of a body intruding in said object field.
Claim 3
Dependent Claim
51 words
A catacoustic system in accordance with claim 1 wherein there are at least two high resolution sonar apparatus directed at two object fields laterally spaced a known distance, whereby the time interval between intrusion in one object field and intrusion in the second object field indicates velocity of the intruding body.
Claim 4
Dependent Claim
25 words
A catacoustic system in accordance with claim 1 wherein said transducer has a line of focus lying substantially in the plane of the water surface.