Garage door opener using transmitter with SAW oscillator modulator
US4684853A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 25, 1986 |
| Grant date | Aug 4, 1987 |
| Priority date | — |
| Expiry date | Jul 25, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07C2009/00928
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A radio frequency (r-f) transmitter has an electric oscillator circuit for producing an oscillating r-f signal in an antenna. A feedback sub-circuit of the oscillator circuit includes a surface acoustic wave (SAW) resonator for stabilizing the oscillations. The feedback circuit has a Q of less than 12000. There is a modulation sub-circuit of the oscillator circuit which includes a voltage variable capacitor. The voltage variable capacitor responds to input voltage variations to modulate the capacitance of the feedback circuit, thereby modulating the frequency of the transmitter. A garage door opener system employing the transmitter is also disclosed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.