Resonant circuit detection, measurement and deactivation system employing a numerically controlled oscillator
US6232878A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 20, 1999 |
| Grant date | May 15, 2001 |
| Priority date | — |
| Expiry date | May 20, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B13/242
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
An apparatus for measuring electrical characteristics of a resonant circuit without physically contacting the resonant circuit. The EAS system includes a numerically controlled oscillator for generating an alternating electric signal, the frequency of the alternating electric signal varying in accordance with a numerical frequency control signal; a transmitting antenna connected to the numerically controlled oscillator for establishing an electromagnetic field within a measurement zone; a receiving antenna for sensing disturbances to the electromagnetic field within the measurement zone; a receiver for receiving signals from the receiving antenna representative of disturbances to the electromagnetic field and for determining the Q and center frequency of the resonant circuit; and a clock having a substantially fixed frequency connected to the numerically controlled oscillator. The frequency of the alternating electric signal is restricted to being an integer multiple of an integer sub-multiple of the clock frequency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.