ASPECTS OF COMMUNICATIONS I43 



the high noise level at the diving platform, the results obtained with these systems were not 

 completely satisfactory. 



HABITAT - SHORE 



Benthic laboratory, a multichannel data transmission station was placed on the bottom 

 close to Sealab. The following habitat -to -shore links were provided through this station. 



Benthic link 2 - Two-way, push-to-talk microphone loudspeaker. This station was moni- 

 tored in benthic control center 24 hours a day. The benthic control watchstander processed 

 any call immediately and patched through for two-way communications to the public telephone 

 lines or to any control station on the Scripps campus. 



Benthic link 3 - Telephone type handset located at the port watch station. No speaker. Has 

 the same capability as benthic link 2. 



Benthic Link 4 - Two-way telephone handset near trunk. This station was not monitored in 

 benthic control. Calls had to be organized via links 2 or 3. The other capability is the same, 

 but it is intended primarily for a telephone patch. 



Benthic links 5, 6, 7 - Open microphones located in berthing, galley, and laboratory areas 

 of Sealab. These microphone outputs were telemetered to shore and could be patched through 

 to PIO, the psychological station, or shore control. Most of the time these links were patched 

 to the shore control closed-circuit TV monitors. 



Benthic link 8 - Electrowriter receivers but no transmitters were located in benthic shore 

 control and at the physiological station. They were not used. 



HABITAT TO SWIMMER 



To enable the swimmer to communicate with the habitat while on a sortie, two means of 

 communication were planned. One was a sonic type with a maximum range of 1000 ft, and the 

 other was a wire-type intercom with a 300-ft range. 



AQUASONIC UNDERWATER COMMUNICATOR 



Frequency Range: 42 kc 

 Modulation: AM 

 Battery Life: 80 hr 

 Range: 1000 ft 

 Depth: 300 ft 



SWIMMER INTERCOM 



Frequency Response: 300 cps - 3 kc 

 Battery Life: 40 hr 

 Range: 300 ft 

 Depth: 300 ft 



The Aquasonic had been used during acoustic tests at the U.S. Navy Mine Defense Laboratory 

 with the Mark VI scuba. Four diver units were placed in Sealab II for swimmer use. A surface 

 unit was also installed to communicate with the swimmer and/or support vessel. Communica- 

 tion tests, intelligibility in particular, were planned using the swimmer units. Due to a crowded 

 diving schedule, the first Aquasonic was connected to a Mark VI scuba and tested on day 6. An 

 aquanaut tested the rig and attempted to communicate with the habitat. Because of the normal 

 back pressure of the Mark VI, the Bioengionics mask lost gas around the edges. This loss 

 caused some difficulty in breathing. The receiver section of the swimmer unit worked fine, but 



