System connects seven observers, diver, and spare station, and utilizes public address system with underwater speakers to provide two-way communications between test subject and personnel in control of life support, so that test personnel are warned immediately of malfunction in pressure suit or equipment

Smith, H. E.

English

NASA Technical Reports Server

September 1971
	
Brief 71-10344 
NASA TECH BRIEF 
Marshall Space Flight Center 	 W 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the. Tech Brief program may 
be directed to the Technology Utilization Off ice, NASA, Code KT, Washington, D. F. 20546. 
Communications System for Zero-C Simulation Tests in Water 
.
A communications system for personnel conduct-
ing underwater neutral buoyancy experiments pro-
vides two-way communications between the test 
subject and personnel in control of life support, so 
that test personnel may be advised immediately of 
any malfunction in the pressure suit or equipment. 
The equipment was designed for use during tests 
concerned with fabrication, assembly, maintenance 
and repair of large structures and associated apparatus 
under conditions of weightlessness, as simulated by 
a water tank in which the test subject in a pressure 
suit is submerged. 
The communications system connects seven 
observers, the diver, and a spare station, with all 
communications being broadcast over a public 
address system which includes underwater speakers. 
The system was designed with nine two-way com-
munication siatios and three one-way stations. The 
one-way stations include a public address speaker 
system designed to drive 20 W peak audio power, 
and an underwater speaker system capable of driving 
100 W audio power. The underwater system con-
sists of two 50 W amplifiers. Each amplifier may be
used to drive two 16 Q, 25 W underwater speakers; 
however, it has been determined that, for the particular 
size water tank used for the tests, two 25 W speakers 
are adequate. The system was designed to switch 
either amplifier to either set of speakers, with the 
capability of putting 100 W of audio power into the 
water if needed, and also to operate from a 12 V 
battery stand-by power source. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
Code A&TS-TU 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B71-10344 
Patent status: 
No patent action is contemplated by NASA. 
Source: H. E. Smith 
Marshall Space Flight Center

(M F S-2 1357) 
Category 02 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned.rights.
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Communications system for zero-g simulation tests in water

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