The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 02, 1991
Filed:
Jul. 10, 1989
Tsuyoshi Nakajima, Takarazuka-shi, Hyogo-ken, JP;
Yuji Ikeda, Kobe-shi, Hyogo-ken, JP;
Other;
Abstract
A period of a correlation signal from a laser Doppler velocimeter is calculated from crossing points at which a correlation function crosses over a threshold level by clipping and digitizing a Doppler burst signal, thereby enabling an accurate and real time measurement to be made of a flow velocity, even in low SNR Doppler signals. Smoothing the waveform of a correlation signal further improves measurement accuracy. When the threshold level is set to be the 1/2 value of the autocorrelation function at .tau.=0, a crossing point is precisely detected even in an uneven correlation function or small amplitude of the crosscorrelation function, thus further increasing measurement accuracy.