System and method for modulating a frequency signal
US6275539A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 20, 1998 |
| Grant date | Aug 14, 2001 |
| Priority date | — |
| Expiry date | Jul 20, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/12
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A radio frequency transmitter circuit including a user input switch for producing an input signal, an oscillator for producing a frequency signal having a first frequency, an antenna connected to the oscillator for broadcasting the frequency signal, a coupling circuit disposed a predetermined distance from the antenna, and a microprocessor for enabling the oscillator and activating the coupling circuit in response to the input signal. When the coupling circuit is activated, a reflected impedance, derived from a change in inductance, is reflected from the coupling circuit upon the antenna thereby shifting the frequency signal to a second frequency. Sequentially activating and deactivating the coupling circuit modulates the frequency signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.