Detection of the distance between an electromagnetic transponder and a terminal
US6473028B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Apr 5, 2000 |
| Grant date | Oct 29, 2002 |
| Priority date | — |
| Expiry date | Apr 5, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K19/0723
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for determining the distance separating an electromagnetic transponder from a terminal generating a magnetic field by a first oscillating circuit, the transponder including a second oscillating circuit, upstream of a rectifying circuit adapted to providing a D.C. voltage. The method includes storing a first information relative to the level of the D.C. voltage when the second oscillating circuit is tuned on a determined frequency; storing a second information relative to the level of the D.C. voltage after having caused a frequency detuning of the second oscillating circuit; and comparing the two stored pieces of information.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.