Dual mode tracking system
US6353406B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 24, 1999 |
| Grant date | Mar 5, 2002 |
| Priority date | — |
| Expiry date | Jun 24, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07C9/28
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
System for tracking mobile tags. Cell controllers with multiple antenna modules generate a carrier signal which is received by the tags. Tags shift the frequency of the carrier signal, modulate an identification code onto it, and transmit the resulting tag signal at randomized intervals. The antennas receive and process the response, and determine the presence of the tags by proximity and triangulation. The recursive-least squares (RLS) technique is used in filtering received signals. Distance of a tag from an antenna is calculated by measuring the round trip signal time. The cell controllers send data from the antenna to a host computer. The host computer collects the data and resolves them into positional estimates. Data are archived in a data warehouse, such as an SQL Server. Also disclosed is an article tracking system that supports both active and passive tags with a cell controller able to read both passive and active tag signals.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.