### ASA 126th Meeting Denver 1993 October 4-8

## 4aEA8. Linearizing the output of nonlinear transducers by preprocessing
their input signals.

**S. E. Forsythe
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*Naval Res. Lab., Underwater Sound Reference Detachment, P.O. Box 568337,
Orlando, FL 32856
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A technique has been developed at USRD to drive transducers to amplitudes
at which nonlinearities in the output normally become evident while maintaining
the output signal as a faithful copy of the drive signal. This is done by
preprocessing the desired signal using a transducer model that includes the
transducer's nonlinearity. The model is stated as a system of coupled ordinary
differential equations (ODEs) which define the dynamic variables of the system
(positions, velocities, accelerations) as well as the parameters of the system
(masses, stiffnesses, viscosities, etc.). Instead of integrating the ODEs using
the known drive, as would be done to predict the system's output, the ODEs are
explicitly solved ``backwards'' given the desired output. This solution
typically requires the accurate numerical calculation of derivatives as well as
the point-by-point solution of simultaneous nonlinear equations. Techniques for
the efficient solution of the equations as well as solubility issues are
discussed. [Work support by Space & Naval Warfare Systems Command.]