Recommendation Where Instrument Should Be Researched and 

 Developed: 



U. S. Industry. 



Relative Importance to U. S. National Oceanogr aphic Program: 



Instrument system priority 5. 



II. f. MARINE SEISMIC RECEIVING SYSTEM 



Primary Use: 



To be utilized on oceanographic survey ships to measure and 

 record the various characteristics of the structure of the sea floor as 

 applicable to acoustical propagation studies of the water volume, the 

 bottom sediments, and the underlying structures. 



Requirements and Specifications: 



a. To perform reliably on oceanographic survey ships, in sea 

 states of through 5, with ship stopped ("lying-to"). 



b. To be operable in coastal and oceanic regions, in water depths 

 of to 6, 500 fathoms. 



c. To be designed so that the equipment is portable, compact, 

 rugged, sinnple, requiring minimum maintenance, and readily and 

 easily transferable fromi one ship to another. 



d. The receiving hydrophone must be so designed as to permit 

 reliable detection of shots as far as 100 nautical miles away. 



e. Receiving hydrophone frequency: 



(1) Range: to 10 kc s . 

 (Z) Accessory Filters : 



(a) Filters to permit the selection of high frequency 

 band (usually greater than 4 kcs.) for the resolution of thin-bedded 

 strata. 



402 



