ACOUSTIC MICROBUBBLE SPECTRUM ANALYZER.
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)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 30, 1969
- Accession Number
- AD0695068
Entities
People
- William R. Turner