UNCLASSIFIED 



Security Classification 



DOCUMENT CONTROL DATA -R&D 



ity classification ot title, body of abstract and indexing annotation muxt be entered when the overall report is classified) 



I. originating activity (Corporate author) 



Naval Undersea Warfare Center 

 San Diego, California 92152 



2a. REPORT SECURITY CLASSIFICATION 



UNCLASSIFIED 



2b. GROUP 



3 REPORT TITLE 



A PORTABLE, GENERAL -PURPOSE UNDERWATER SOUND MEASURING SYSTEM 



4 DESCRIPTIVE NOTES (Type of report and inclusive dates) 



Research and Development Report, January 1965 - July 1966 



5 AUTHORtS) (First name, middle initial, last name) 



M.A. Calderon and G. M. Wenz 



6- REPORT DATE 



7a. TOTAL NO- OF PAGES 



46 



7b. NO. OF REFS 



5 



Ba. CONTRACT OR GRANT NO 



ORIGINATOR'S REPORT NUMBER(S) 



b. PROJECT NO SF 101 03 15 



Task 8119 

 (NEL L20471) 



TP 25 



9b. OTHER REPORT NO(SI (Any other numbers that may be assigned 

 this report) 



10 DISTRIBUTION STATEMENT 



This document has been approved for public release and sale; its distribution 

 is unlimited. 



II. SUPPLEMENTARY NOTES 



12. SPONSORING MILITARY ACTIVITY 



Naval Ship Systems Command 

 Department of the Navy 



3 ABSTRACT 



A portable underwater sound-pressure measuring system was developed and 

 tested. The system was shown to be capable of measuring very low ambient -noise 

 levels. High self-noise levels at frequencies less than 50 to 63 Hz are likely to be 

 present if measurements are made from a drifting ship, and the cable is towed at 

 drift velocity, probably because of a combination of flow noise and noise arising 

 from cable vibrations. These high self-noise levels can be satisfactorily eliminated 

 by using a slack cable system as described in the report. 



DD, f n o? 65 1473 (PAGE ■ 



UNCLASSIFIED 



S/N 0101-807-680 1 



Security Classification 



