Visual light landmarks for mobile devices

摘要: The omnipresence of indoor lighting makes it an ideal vehicle for pervasive communication with mobile devices. In this paper, we present a scheme that enables interior ambient LED systems to send data devices using either cameras or light sensors. By exploiting rolling shutter camera sensors are common on tablets, laptops and smartphones, is possible detect high-frequency changes in intensity reflected off surfaces direct line-of-sight the camera. We demodulation approach allows smartphones accurately frequencies as high 8kHz 0.2kHz channel separation. order avoid humanly perceivable flicker lighting, our system operates at above 2kHz compensates non-ideal frequency response standard drivers by adjusting light's duty-cycle. modulating PWM signal commonly used drive systems, able encode can be localization landmarks. show through experiments how binary shift keying modulation transmit 1.25 bytes per second (fast enough ID code) from up 29 unique sources simultaneously single collision domain. also tags demodulate same signals sensor instead low-power applications.