A system for underground surveying includes a plurality of substantially rigid frames and a plurality of acoustoelectric sensors for generating electrical signals encoding echo responses of underground surfaces. Each of the frames carries at least one of the sensors, the sensors being disposable in effective physical contact with underground structures upon an insertion of the frames through a ground surface. An acoustic energy generator is disposed on at least one of the frames, while position determination componentry is operatively connected to the sensors for determining locations of the sensors relative to one another. An electronic signal processor is operatively connected to the sensors for analyzing the electrical signals in accordance with the determined locations of the sensors to determine surfaces of an object hidden underground and for generating a video signal encoding an image of the object. A video monitor is operatively connected to the processor for displaying the image of the object.

A system for sonically probing a seabed comprises at least one row of transducers that each can produce a sonic beam, and a corresponding row of sonic detectors. Each transducer is independently energized to produce a narrow sonic beam, with resulting seabed or subsea echoes being detected to produce one pixel of a display formed by an X-Y array of pixels, before a next transducer is energized and its echoes are detected to produce another pixel of the display. When the system detects a large change in echo amplitude at adjacent seabed locations, then scanning at those locations is accentuated by analysis and by additional sonificiation at different frequencies. The transducers are closely spaced, at a center-to-center distance of typically about 3.5 cm, to provide good horizontal resolution. Each transducer is energized to produce a sonic pulse which, dependent on the application, has a carrier frequency of 0.25 MHz. This results in an optimized narrow sonic beam, with each pulse having a duration on the order of 10 to 100 microseconds to produce a modulation frequency on the order of 200 kHz to 5 Khz, and with each pulse having a high maximum energy to create a wide frequency bandwidth in the seabed.

A system for sonically probing a seabed comprises at least one row (14) of transducers (22) that each can produce a sonic beam, and at least one sonic detector (24). Each transducer is independently energized to produce a narrow sonic beam (40), with resulting seabed or subsea echoes being detected to produce one pixel of a display (60, 80, 90, 150) formed by an X-Y array of pixels, before a next transducer is energized and its echoes are detected to produce another pixel of the display. When the system detects a large change in echo amplitude at adjacent seabed locations, then scanning at those locations is accentuated by analysis and by additional sonification at different frequencies. The transducers are closely spaced, at a center-to-center distance (G) of less than 25 cm, to provide good horizontal resolution and usually lie within 6 meters from the seabed. Each transducer is energized to produce a sonic pulse which, dependent on the application, has a carrier frequency (32) of at least 200 kHz. This results in an optimized narrow sonic beam, with each pulse having a duration (A) on the order of 10 to 100 microseconds to produce a modulation frequency on the order of 200 kHz to 5 kHz, and with each pulse having a high maximum energy to create a wide frequency bandwidth in the seabed.

A method for investigating structural integrity utilizes a carrier member having a flexible surface and a plurality of electromechanical transducer elements attached to the carrier member, the transducer elements being spaced from each other along at least two spatial dimensions. The method includes conforming the flexible surface to a solid structural member, so that a substantial portion of the flexible member is in effective wave-transmitting engagement with the structural member, thereafter transmitting pressure waves from at least one of the transducer elements into the structural member, receiving pressure waves reflected from an internal structural defect in the structural member in response to the pressure waves transmitted from the one of the transducer elements, and analyzing the received pressure waves so as to detect the structural defect.

A method for investigating structural integrity utilizes a carrier member having a flexible surface and a plurality of electromechanical transducer elements attached to the carrier member, the transducer elements being spaced from each other along at least two spatial dimensions. The method includes conforming the flexible surface to a solid structural member, so that a substantial portion of the flexible member is in effective wave-transmitting engagement with the structural member, thereafter transmitting pressure waves from at least one of the transducer elements into the structural member, receiving pressure waves reflected from an internal structural defect in the structural member in response to the pressure waves transmitted from the one of the transducer elements, and analyzing the received pressure waves so as to detect the structural defect.