Crystal controlled transmitter
US4864636A · kind A · utility
Inventor
Key dates
| Filing date | Feb 19, 1987 |
| Grant date | Sep 5, 1989 |
| Priority date | — |
| Expiry date | Feb 19, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03B2200/0012
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A short distance, battery powered, amplitude modulated, crystal controlled RF transmitter for transmitting encoded security information. In its preferred embodiments, the transmitter comprises a novel fifth overtone crystal oscillator which self-produces a carrier frequency at the third harmonic of the fifth overtone of the crystal's fundamental frequency, which carrier frequency is coupled by a series resonant trap, or a pi network, tuned to the carrier frequency to an amplifier stage where the carrier is amplitude modulated via pulse position encoded binary security data. In an alternative embodiment, the transmitter comprises matched crystal oscillator, tripler and amplifier stages. Also disclosed is an antenna including a battery clip contact.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.