APPENDIX B: TECHNICAL SPECIFICATIONS, 

 HYDROPHONE-PREAMPLIFIER 

 ASSEMBLY 



U.S. Navy Electronics Laboratory, 

 San Diego, California 



19 October 1965 



1.0 SCOPE 



These technical requirements cover a hydrophone - 

 preamplifier assembly to be used as part of an underwater 

 sound-pressure-level measuring set which includes con- 

 necting cables up to 1000 feet in length. An important 

 feature of this transducer is the capability of measuring 

 very low sound-pressure levels. The assembly shall 

 include a hydrophone, preamplifier with calibrate resistor, 

 case, cable, and connector. 



2.0 REQUIREMENTS 



2. 1 General. The construction shall be modern and of 

 good commercial practice. The assembly shall have suf- 

 ficient strength and ruggedness to withstand normal han- 

 dling aboard ship at sea without suffering damage. 



2.2 Hydrophone. 



2.2.1 Voltage Response . Not less than -90 dBV for 

 1 dyn-cm" 2 sound pressure. Preference will be given to 

 that design which minimizes the dependence of voltage 

 response on static pressure and temperature. The varia- 

 tion of voltage response with pressure and temperature 

 shall be stated by the supplier. 



2.2.2 Capacitance. Not less than 0. 001 microfarad. 



2.2.3 Performance Goal . The characteristics are not 

 specified exactly herein since the supplier should select 

 that combination which, when used with his preamplifier, 



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