Apparatus and methods for performing acoustical measurements
US6199423A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 19, 1999 |
| Grant date | Mar 13, 2001 |
| Priority date | — |
| Expiry date | Nov 19, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/102
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus and methods for performing acoustical measurements are provided having some and preferably all of the following features: (1) the system is operated under near-field conditions; (2) the piezoelement or piezoelements used in the system are (a) mechanically and electrically damped and (b) efficiently electrically coupled to the signal processing components of the system; (3) each piezoelement used in the system includes an acoustical transformer for coupling the element to a gaseous test medium; (4) speed of sound is determined from the time difference between two detections of an acoustical pulse at a receiver; (5) cross-correlation techniques are employed to detect the acoustical pulse at the receiver; (6) fast Fourier transform techniques are used to implement the cross-correlation techniques; and (7) stray path signals through the body of the acoustic sensor are removed from detected signals prior to signal analysis. Techniques are also provided for performing acoustical measurements on gases whose thermodynamic properties have not been measures and on mixtures of compressible gases. Methods and apparatus for performing feedback control of a gas of interest in a mixture…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.