CONTENTS 



INTRODUCTION. . . page 5 



SYSTEM DESCRIPTION. . . 6 



Hydrophone and Preamplifier. . . 7 



Cable. . . 11 



Calibrate Boxes. . . 14 



Sound-Level Meter and Analyzer. . . 17 



Tape Recorders. . . 18 



SELF -NOISE SOURCES. . . 19 



FIELD TESTS... 20 



Hydrophone Suspensions. . . 20 

 Cable Systems. . .24 



RESULTS OF FIELD TESTS. . . 30 

 Self-Noise. . . 30 

 Suspension and Cable Systems. . . 33 



CONCLUSIONS. ..33 



RECOMMENDATIONS. . . 34 



REFERENCES... 35 



APPENDIX A: HYDROPHONE -DEPTH MEASURING 

 SYSTEM. . . 37 



APPENDK B: HYDROPHONE -PRE AMPLIFIER 



ASSEMBLY. . . 39 



APPENDIX C: CABLE SPECIFICATIONS. . . 45 



TABLES 



1 Electrical Properties of the Cable. . . page 12 



2 Lower and Upper Cutoff Frequencies and Midpoint 



Frequencies for the Octave Bands of the Sound Level 

 Meter. . . 17 



