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. 30, 2002
Filed:
Aug. 29, 2000
Robert W. Boyd, Edison, TN (US);
Donald K. Belcher, Rogersville, TN (US);
Michael A. Wohl, Rogersville, TN (US);
Wherenet Corporation, Santa Clara, CA (US);
Abstract
An asset management radio location system uses time-of-arrival differentiation for random and repetitive spread spectrum, short duration transmissions from object-attached tags, to geolocate objects within a monitored environment. An object location processor is coupled to distributed tag transmission readers over signal transport paths having different transport delays, and carries out time-of-arrival differentiation of first-to-arrive transmissions from a tag to determine where its object is located. Geolocation errors associated with variations in parameters of the signal transport paths are effectively removed by installing one or more 'reference' tags, whose geolocations are precisely known. Using a background calibration routine that is exercised at a relatively low cycle rate, emissions from the reference tags are processed and coupled to the geolocation processor. The calculated geolocations of the reference tags are compared with their actual locations. Any offset between the two geolocation values is used to adjust time delay offsets associated with signal transport paths between the readers and the geolocation processor.