TELEMETERING UNDERWATER 



209 



RESULTS 



The following tests were performed at the therapeutic pool at the Philadelphia General 

 Hospital vl3 ft wide and approximately 25 ft long) and at the local YMCA (pool is approximately 

 40 X 70 ft) to confirm basic operations capability of the system (Fig. 85). Tests indicated that 

 all circuits were performing within specifications. 



A second series of tests were performed 

 in the Little Magathey River (Maryland) to test 

 the operation of the system in a large salt- 

 water body. Good signals were obtained at 

 distances up to 50 ft. Beyond that, range drop- 

 out was severe. Reasonable interpretation of 

 range from this data is not possible due to the 

 fact that the water conditions were not as ex- 

 pected; i.e., actual depth of the water was 3.0 

 ft, with much swamp grass which absorbed the 

 signal. Figure 86 shows data obtained at a 

 distance of 30 ft. The data at this time showed 

 significant amounts of muscle tremor due to 

 the fact that excessive exertion was needed to 

 move through the vegetation. When the subject 

 relaxed, significant improvement in the quality 

 of the received signal was observed. 



Data are also shown (Fig. 86) when the 

 diver was at a distance of 60 ft from the record- 

 ing appartus. Although the data showed signifi- 

 cant amounts of dropout, heart- rate data were 

 still available. 



Fig. 85. Experimental tests of sonic 



telemetry equipment 



A and B - in 15 « 25 ft pool 



C and D - in 40 ^ 70 ft pool 



Final study of the equipment before deliv- 

 ery to Sealab was performed at the Aquarama 

 in Philadelphia at a depth of 10 ft and a distance 

 of 50 ft from the recording apparatus. Before 

 entry to the water, a baseline air test was per- 

 formed using the equipment. The results are 

 shown in Fig. 87. Figure 87 shows data ob- 

 tained at a distance of 20 ft after the diver had 

 undertaken extreme physical exertion. 



Tests with the first diving team have 

 yielded high-quality electrocardiograms at 

 distances up to 100 ft and at a depth of 220 ft 

 (Fig. 88). Additional tests performed under 

 similar conditions yielded similar results. No tests were performed beyond this distance; con- 

 sequently, the exact determination of maximum range is hot possible. 



FUTURE RECOMMENDATIONS 



Experience at Sealab has shown that the underwater physiological telemetering equipment 

 requires too much time and experience from personnel in Sealab and topside. To alleviate this 

 problem, a new design policy emphasizing ease of installation and operation of the equipment 

 will be adhered to. The following factors will be studied to simplify equipment operation. 



1. Electrode Placement 



In order to obtain good electrocardiograms, the use and placement of proper electrodes is 

 crucial. Personnel in the Sealab found that the Beckman electrodes required too much time to 



