Reference frequency from ambient light signal
US9184698B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 11, 2014 |
| Grant date | Nov 10, 2015 |
| Priority date | — |
| Expiry date | Mar 11, 2034 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L7/06
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A system includes an oscillator referenced to a frequency extracted from periodic intensity modulations of incident light. The incident light can be intensity modulated based on the frequency of the AC voltage that powers artificial lighting. The system includes a light-sensitive element configured to generate an output signal indicative of an intensity of incident light and a controller. The controller can receive a first input signal based on the output signal from the light-sensitive element. In the presence of artificial lighting, the first input signal has a frequency based on a reference frequency at which an intensity of light incident on the light-sensitive element periodically varies. The controller can generate a control signal based in part on the reference frequency. The controller can provide the generated control signal to the adjustable oscillator to thereby adjust the oscillator frequency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.