Apparatus and methods for performing acoustical measurements
US6279379A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 19, 1999 |
| Grant date | Aug 28, 2001 |
| Priority date | — |
| Expiry date | Nov 19, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/102
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus (15, 30) and methods for performing acoustical measurements are provided having some and preferably all of the following features: (A) the system (15, 30) is operated under near-field conditions; (B) the piezoelement (40) or piezoelements (40, 48) used in the system are (i) mechanically (41, 49) and electrically (13, 16) damped and (ii) efficiently electrically coupled to the signal processing components of the system; (C) each piezoelement (40, 48) used in the system includes an acoustical transformer (42, 50) for coupling the element to a gaseous test medium (9); (D) speed of sound is determined from the time difference between two detections of an acoustical pulse (81, 82) at a receiver (40, FIG. 3; 48, FIG. 7); (E) cross-correlation techniques are employed to detect the acoustical pulse at the receiver; (F) forward and inverse Fourier transforms employing fast Fourier transform techniques are used to implement the cross-correlation techniques; in such a mathematical manner that the peak of the cross-correlation function corresponds to the detection of a pulse at the receiver and (G) stray path signals through the body (31) of the acoustic sensor (15, 30) are removed f…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.