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:
May. 23, 1995
Filed:
Jan. 11, 1993
Jeffrey S Rosenberg, Tulsa, OK (US);
TDW Delaware, Inc., Wilmington, DE (US);
Abstract
Two geophones located above an underground pipeline are spaced from each other and adjacent to both sides of a benchmark location. As a pig travels through the pipeline sound waves are generated. As a pig approaches a benchmark location, sound waves are received first by the geophone which is closest to the source of the sound waves, that is, the upstream geophone and then by the downstream geophone. The geophones generate electrical signals that are fed to a comparator circuit which is connected to upstream and downstream indicators, one of which is activated when a pig passes the benchmark depending on whether the sound was first received by the upstream or downstream geophone. An alternate embodiment adds a magnetometer at the benchmark location capable of sensing changes in the ambient magnetic field caused by the passage of a pig.