212 



TELEMETERING UNDERWATER 



Body Temperature — Body- temperature 

 data are of prime importance, since one of the 

 limiting factors to man's performance in the sea 

 is his ability to endure loss of body heat to the 

 water. Telemetering of body-temperature 

 data should greatly help in the evaluation of 

 the various experimental heated wet suits. 



Fig. 89. Sonic transmitter with case 

 removed 



Additional EKG Leads — It is well known 

 in medical practice that more than one elec- 

 trocardiogram is necessary to get a maximum 

 amount of data from the heart. Additional 

 leads will provide the necessary data. 



Electroencephalograms— Telemetering of 

 the EKG may be implemented in the telemeter- 

 ing system, since the bandwidth requirements 

 for the EKG are actually less than the elec- 

 trocardiogram. It would merely be necessary 

 to provide a higher gain amplifier in the trans- 

 mitter to compensate for the smaller signal 

 levels of the EKG. 



A Voice Channel — Addition of a voice chan- 

 nel will be very helpful in correlating the data 

 received for the type of physical activity. In 

 addition, the voice channel would also serve 

 as an excellent means of communication be- 

 tween divers and personnel on Sealab. The 

 bandwidth requirements for a voice channel 

 are considerably greater than those of the 

 EKG channel; consequently, the design of the 

 voice channel might not be practical in view 

 of our transmitter configuration. However, 

 the great usefulness of the voice channel will 

 make it worthwhile to investigate. 



6. Extension of Transmitting Range and Improvement of Signal 



In tests at Sealab to date, high-quality signals have been received at the maximum distance 

 tested (100 ft through the water). Therefore, the range of the system in its present form is 

 greater than 100 ft. However, significant improvements can be made in the efficiency of the 

 final amplifier of the transmitter. In addition, low- noise transistors can be used in the front 

 end of the receiver and the EKG preamplifier of the transmitter. Both of these changes should 

 result in significant increases in range and reductions in the amount of noise in the received 

 electrocardiogram . 



7. Packaging 



The design philosophy for packaging future equipment should be to allow for maximum 

 flexibility of the equipment. For instance, all telemetry channels will be constructed as plug- 

 ins to the basic transmitter. Several plug- ins will be constructed. The plug- in will be chosen 

 to telemeter the data for a given mission. As an example of plug- in types, there will be a 

 single- lead EKG plug- in which will give the same performance as the equipment used on Sealab 

 II. The second type of plug-in will consist of four temperature channels. Another example 

 would be a plug- in designed for one EKG and one EEG channel. The advantage of the plug- in 

 system is that if one particular data type is unsuccessful, other plug- ins can be used so that the 

 system will not be rendered useless. 



