1. A high resolution sound wave detecting system having a fan-shape beam of receiver sensitivity comprising a pair of transducers having elongated active faces coplanar and in end to end relation, an output signal channel for each transducer, means including two local oscillators of different frequencies connected to heterodyne against each other for producing timing pulses having a repetition rate equal to the frequency difference of said oscillators and individually against the output signals ...

1. A towable detecting gear adapted for dragging over a water-submerged sace comprising a tail portion, a towing cable having its trailing end enclosed in a tail portion and having at least one insulated conductor, a weight member secured to said cable at the forward end of the tail portion and having sufficient negative buoyancy to drag along said submerged surface when under tow, a plurality of detecting devices disposed at intervals along the cable in said tail portion and in electrical commu...

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, di...

1. In a sonic echo system for classifying objects proud on the ocean floor in which a submarine vehicle moves through the ocean at a constant height above the ocean floor, scanning means for simultaneously deriving separate electric signals corresponding to the sonic reflecting values of parallel strips of the ocean floor extending athwartships of said vehicle, means for simultaneously storing said separate signals on a record medium, and means for serially reproducing the stored signals.