Abstract: Acoustic transponders are attached to sections of a submarine cable for use in accurately locating the cable during deployment or retrieval. An acoustic signal at one frequency, transmitted from the surface or elsewhere, stimulates one of the transponders to generate a first reply signal at a different frequency. The acoustic reply signal generated by each transponder is used to determine the location of that transponder and thus the location of its associated section of the cable. In order to measure cable tension during deployment or retrieval, a strain gauge at each transponder senses the tension of the cable at the location of its associated transponder. After each transponder transmits its first reply signal, it transmits a second reply signal delayed from the first reply signal by a time interval which is controlled by the output of its associated strain gauge.

Abstract: The definition of a photographic emulsion of the positive acting type that would normally produce a positive image is improved by normally exposing the emulsion to actinic radiation and developing the photographic emulsion, bleaching it, exposing the emulsion again to actinic radiation and redeveloping it to reverse the image that would normally result on the film.

Abstract: A system for measuring the depth of the ocean, or other body of water, from a moving vessel uses acoustical sounding from the vessel and enables improved bottom definition during high-speed vessel travel. A succession of pulses of different tone frequencies is transmitted from the vessel. The echoes produced when these tone pulses reflect from the water bottom are received at the vessel and are sorted according to frequency. This arrangement assures that the determination of the transit time of a pulse at one frequency is not confused by receipt of an echo at another frequency. The transit times of the several pulses and their echoes are measured for use in determining water depth.