plex and expensive electronics, with an expected decrease in the 

 system's reliability. Digital and variable frequency systems are 

 somewhat similar in that the data signal can be transferred rea- 

 sonably undistorted over long distances, but each requires a trans- 

 ponder which is highly sensitive to temperature effect. Digital 

 systems readily available are presently restricted because of the 

 encoder size and complexness and because of their excessive power 

 requirement. The variable frequency system, in addition to pre- 

 senting a difficult tracking problem due to center frequency devia- 

 tion, also becomes complex and costly because of required filter- 

 ing, frequency counters and converters or printers to record the 

 data in a usable form. Mention of many attractive features has 

 been intentionally avoided and troublesome features stressed in 

 the hope that from this vast assembly of talent may come the 

 development of a simplified, reliable, and economical sensor 

 principle. If sensors are developed to operate from buoys and 

 stable platforms, it is logical to assume that they can be economi- 

 cally adapted for underway operations. 



Data recording, the third problem area, is not considered to 

 be as difficult to solve. Certainly from the vast number of tech- 

 niques in current use, adaptions can be made which can operate 

 from the limited power supply of a buoy to record sensor outputs. 

 Perhaps the most stringent requirement is that the record be 

 compatible with automated techniques employed at the National 

 Oceanographic Data Center. 



As has been mentioned in previous talks, use of sound offers 

 another means for measuring the ocean's physical characteristics. 

 The Coast and Geodetic Survey program for utilizing sound to probe 

 the oceans' mysteries requires the development of a narrow beam 

 stabilized transducer for better bottom delineation in deep water, as 

 well as a bottom scanner to define more clearly the shape and con- 

 tour of the bottom. Further instrumentation is needed to make pos- 

 sible deeper penetration of the sea and to reveal the geological 

 structure beneath the ocean floor. Development of instrumentation 

 is needed, for both underway and stopped operations to measure 

 bottom sound absorption and sound velocity useful in under seas war- 

 fare. Improved instrumentation using sound could nnake possible 

 measurement of the little -known internal ocean wave motion so that 

 the wave characteristics could be quickly and accurately determined. 

 Sound could be used more effectively to study the structure of water 

 density for a better understanding of changes due to temper atvire 



95 



