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:
Feb. 24, 1981
Filed:
Sep. 28, 1979
Applicant:
Inventors:
Norman E Flournoy, Houston, TX (US);
Robert W Pitts, Jr, Houston, TX (US);
Assignee:
Texaco Inc., White Plains, NY (US);
Primary Examiner:
Int. Cl.
CPC ...
G01S / ;
U.S. Cl.
CPC ...
367118 ; 367135 ; 73 4 / ;
Abstract
A method of marking a pipeline location eliminates ambiguity in case there are leaks near the location of a marker. It employs a marker that emits two separate frequencies that are modulated by a third frequency lower than either of the other two. Detection of the marker on a pipeline pig is done by separating the two frequencies and demodulating the third. Then by determining the coincidence of all three for a predetermined number of consecutive cycles of the third frequency, the marker location will be positively identified.