Accession Number : AD0695068

Title :   ACOUSTIC MICROBUBBLE SPECTRUM ANALYZER.

Descriptive Note : Technical note 14 Mar 66-30 Nov 68,

Corporate Author : VITRO LABS SILVER SPRING MD

Personal Author(s) : Turner,William R.

Report Date : 30 SEP 1969

Pagination or Media Count : 60

Abstract : The instrument is intended to analyze in situ microbubble populations by detecting differential ultrasonic velocity and attenuation between a seawater sample and a reference liquid over continuous frequency range from 0.1 to 5.0 MHz. Wave guides are used to confine the ultrasonic paths. The first pass wave guide signals are separated from multiple reflections by using a ramp frequency signal heterodyning the wave guide output signals against the ramp, and selecting the lowest difference frequency. The differential velocity is obtained digitally by timing the periods of processed wave guide signals, and the differential attenuation by logarithmically comparing amplitudes. Generation of a sufficiently linear and noise-free ramp signal and design of identical wide band ultrasonic transducers were particular problems addressed during the contract period. (Author)

Descriptors :   (*UNDERWATER SOUND, REVERBERATION), (*SEA WATER, BUBBLES), (*BUBBLES, DETECTION), SPECTRUM ANALYZERS, ULTRASONIC RADIATION, SOUND TRANSMISSION, ATTENUATION, VELOCITY, WAVEGUIDES, ELECTROACOUSTIC TRANSDUCERS, WAVEFORM GENERATORS

Subject Categories : Test Facilities, Equipment and Methods
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE