Reliable visibile light communication with dark light synchronization
US9264138B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | May 16, 2013 |
| Grant date | Feb 16, 2016 |
| Priority date | — |
| Expiry date | Sep 11, 2033 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2007/045
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
LEDs that transmit or receive data in a VLC channel may create a flickering effect which is caused by the human eye being able to perceive the fluctuations of the light intensity in a LED. To prevent flickering such that the LED is perceived as being illuminated at a constant intensity, the LEDs may emit light based on a pattern of dark and energy slots. During the dark slots, the LEDs may be reversed bias to determine how much light is received. Based on comparing the light received, each VLC system may synchronize respective clocks such that the dark slots align. The VLC systems may then transmit a data frame preamble instructing the other VLC systems to cease synchronization and use the dark slots to receive the data from the data frame. While transmitting the data frame, the VLC systems may continue to use the energy slots to prevent flicker.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.