A small, standard, lithium sulfate hydrophone has been calibrated by a reciprocity-coupler method in the frequency range 20 cps-3 kc/sec and at hydrostatic pressures from 0–16 000 psi. The sensitivity of the hydrophone is stable to within ±0.3 dB in this pressure range.

Diffraction constants for a sphere, a long cylinder, a ring, and a piston at the end of a long tube are derived and presented in a form useful in designing acoustic transducers.

The dielectric and piezoelectric properties of a calcium-modified PbTiO3 ceramic were determined as a function of pressure from 0 to 70 MPa by using an acoustic reciprocity technique. The transverse piezoelectric coefficients (d31, g31) of this material are very small, which results in high values of hydrostatic gh (=g33+2g31) and dh (=d33+2d31) constant. Consequently, the material is considerably more sensitive than lead zirconate titanate (PZT). Measurements of the resonance properties of this ceramic indicated that it is suitable for use in a high-frequency underwater transducer. Prototype transducers were designed and constructed. The free-field voltage sensitivity was measured over the frequency ranges 1–100 kHz and from 200 kHz–2 MHz. The results of these measurements are compared with those obtained from existing high-frequency hydrophone standards. Since this material is a volume expander, it is very useful for electroacoustic transducer applications.

An omnidirectional 25-kHz transducer has been designed for use in bottom-scattering measurements. The transducer can be used either as a projector or when fitted with a preamplifier, as a hydrophone. The requirements for the design are presented and solved with mathematical modeling and analysis. A comparison between theory and measured performance is given. The design of a low-noise preamplifier with integrated circuits is described. 20. DISTRIBUTION/AVAILABILITY OF ABSTRACT ra UNCLASSIFIED/UNLIMITED D SAME AS RPT. D DTIC USERS 21. ABSTRACT SECURITY CLASSIFICATION Unclassified 22a. NAME OF RESPONSIBLE INDIVIDUAL Allan C. Tims DDFORM 1473,84 MAR 83 APR edition may be used until exhausted. All other editions are obsolete. i 22b TELEPHONE (Include Area Code)

The design and construction of the terminal and source transducers, a reciprocal spherical piezoelectric ceramic transducer, and the probe hiydrophones that are part of a new USRD measuring facility are described. The facility is used for the calibration of underwater sound transducers in the frequency range 10 to 4000 Hz at hydrostatic pressure to 10,000 psig and controlled temperature from 3 to 45 0 C. It operates on the principle of active-impedance termination in a rigid-walled, water-filled tube. PROBLEM STATUSThis is an interim report on the problem. PROBLEM AUTHORIZATION