underwater television[¦ən·dər¦wȯd·ər ′tel·ə‚vizh·ən]
Underwater television is used in the search for and inspection of sunken vessels, the examination of submerged portions of vessels and hydraulic engineering structures, and the inspection of underwater communications equipment. It is used to observe divers at work and the ice cover (from submarines). It is also used in the study of marine flora and fauna and in archaeological investigations. In addition, underwater television is used to search for schools of fish and oil deposits, to detect bottom mines, and to monitor underwater tests of armaments. It can be used at depths of up to several hundred meters for practically unlimited periods of time under highly diverse conditions, even in waters contaminated by radioactivity. However, the use of underwater television is limited by the poor illumination of objects in the water as a result of the strong absorption and diffusion of light by water (the range of visibility does not exceed a few tens of meters even in transparent water) and the weak contrast between the objects and the background. Artificial lighting by stroboscopic or laser light sources can increase the range of visibility up to 200 m.
Underwater television systems are closed-circuit systems. The underwater part of such systems includes a television camera, a compound cable, a source or artificial light, and a camera attachment; the above-water portion consists of a display monitor, a control console, and a source of electric power. Underwater television cameras are classified as deepsea or shallow-water and as stationary or movable. Movable cameras are further subdivided into portable, towed, or self-propelled. Vidicons, image orthicons, and other electron tubes that can operate at low levels of illumination are used as television camera tubes. Control of deep-sea cameras and transmission of television signals are carried out by means of hydroacoustic conduits.
The underwater television camera has a self-contained source of electric power. The control signals and electric power for shallow-water cameras are transmitted from the surface vessel through a cable. The same cable serves as both a transmission line for television signals and as a towing line. Underwater television systems also use auxiliary equipment that regulates the immersion depth of the camera, the deflection angle, and the inclination of the camera’s optical axis.
REFERENCEVershinskii N. V. Podvodnoe televidenie, Moscow-Leningrad, 1960
Gabis, N. V. Podvodnoe televidenie. Moscow, 1960.
Televidenie v voennom dele. Moscow, 1969.
N. V. GABIS