Accession Number : AD0709093

Title :   INTERACTION OF TWO SOUND BEAMS IN WATER.

Descriptive Note : Thesis,

Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CALIF

Personal Author(s) : Fulk,Gerald Albert

Report Date : OCT 1969

Pagination or Media Count : 55

Abstract : Modern sonars are large in size. This is a result of several factors connected with operation at low frequencies. Non-linear interaction of two high-frequency sound beams in water may provide a source of low-frequency sound without the use of large transducers. The theory of interaction of two plane waves is reviewed, and conversion efficiency is studied. Early experimental work is also reviewed. To provide new experimental data, primary sources of 385 kHz and 435 kHz are mounted side-by-side in an anechoic tank. The sound field between the parallel beams is explored. A difference-frequency signal is detected, but its amplitude is found to be greater than the theoretical value. Non-linearities in the receiving hydrophone are suspected as contributing to the 50-kHz signal level. Various techniques for eliminating psuedo-sound are discussed, and recommendations for further study are presented. (Author)

Descriptors :   (*UNDERWATER SOUND SIGNALS, INTERACTIONS), TRANSDUCERS, CAVITATION, BROADBAND, NARROWBAND, SONAR SIGNALS, HYDROPHONES, THESES

Subject Categories : Acoustic Detection and Detectors
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE