ASA 124th Meeting New Orleans 1992 October

1pEA11. A multichannel digital system for use in calibrating towed arrays.

S. E. Forsythe

C. K. Brown

Naval Res. Lab., Underwater Sound Reference Detachment, P.O. Box 568337, Orlando, FL 32856

A long-line hydrophone calibrator (LLHC) has been developed at NRL--USRD to serve as a platform for calibrating a variety of towed arrays. The LLHC consists of multiple projectors and hydrophones in a long water-filled pipe. Digital control of the projectors allows a precisely controlled acoustic field to be generated in the pipe. The LLHC makes extensive use of digital signal processing to control and monitor up to 128 acoustic channels. The DSP algorithm for field generation is distributed among 9 signal processors, each controlling 15 acoustic channels. The transfer function of the pipe is characterized by driving each projector separately and recording the responses of all hydrophones to it. To build a specified sound field in the pipe, the inverse of the response matrix is multiplied by the vector of desired hydrophone responses to form the vector of drives required to achieve the desired field. This presentation describes the details of the electronics and software necessary to build the desired field. [Work supported by NAVSEA.]