The Performance of a Parametric Receiver in an Inhomogeneous Medium.
TEXAS UNIV AT AUSTIN APPLIED RESEARCH LABS
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This thesis describes a theoretical and experimental study of the effects of medium inhomogeneities on the performance of a parametric receiver. A review is made of the basic principles of parametric receiver operation and of wave propagation in an inhomogeneous medium. A theoretical analysis is presented for the case of a signal wave source located on the axis of the parametric receiver in a weakly inhomogeneous medium. Expressions are developed that predict the level of amplitude fluctuations in the second-order pressure at the hydrophone of the parametric receiver. Both collimated and spherically spreading pump waves are considered. The experimental study reported in this thesis was conducted in a model tank in which an array of immersion heaters and a perforated screen produced a thermal microstructure. Measurements were made of the coefficient of amplitude variation for the signal, pump, and interaction frequency waves associated with both a nearfield and a farfield parametric receiver. Results are compared to theory and discussed. Author
- Acoustic Detection and Detectors