A Video Telemetry System for Deep Ocean Use
Abstract
A video system for use in deep ocean areas has been designed and prototyped. The basic specifications for the system include the use of a single coaxial cable for towing a camera sled, providing sled electrical power, and allowing the transmission up the cable of video images at a rate as near real time as possible. The underwater section of the system includes underwater low light video cameras, a modulator, a single board IBM PC compatible computer, and a frame-grabber board. A demodulator, computers, frame-grabber boards, and monitors are included in the surface unit. The uniqueness of this system is in the capability of sending a video signal with a bandwidth of 790 kilohertz over a cable which has a 56 dB loss at 1 hz. Also, it is necessary to send a 400 volt DC voltage down the cable in order to provide power to the underwater electronics. A vestigial sideband modulation method is used to transmit the video signal with an 833 kilohertz carrier. The cable itself and a surface equalizer are used to attenuate the upper sideband sufficiently in order to recover the video signal with an envelop detector at the surface. The latter includes a unique sample-hold circuit which effectively provides full wave rectification of the modulated carrier with a high bandwidth.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1990
- Accession Number
- ADA236100
Entities
People
- D. S. Yeadon
- Kenneth Mcdaniel
- Maurice G. Thiele Jr.
- Russell E. Trahan Jr.
Organizations
- United States Naval Research Laboratory