A system, method, and apparatus for communicating information in a light-based signal utilizing a fob device is disclosed. One method disclosed includes encoding transmission information data into a bar code format; generating a signal from the bar code format to simulate a reflection of a scanning beam...http://www.google.com.hk/patents/US20020145043?utm_source=gb-gplus-share專利 US20020145043 - System, method, and apparatus for communicating information encoded in a light -based signal using a fob
