5. Discussions
In order to improve the video quality, an ADC can be used for the digital conversion of the video signal and then the digital video signal can be transmitted via LEDs. By adopting some compression algorithms, one can re-duce the data rate of the digital video signal and avoid using expensive high-speed ADCs. We practically dem-onstrated parallel transmission of audio and video signals using LEDs. For the audio link, the S/PDIF format was adopted to allow transmission of 5.1, 7.1, or 9.1 digital audio signals, which is very attractive for home enter-tainment applications. Since the PDs used have their peak in the red wave-length region, then the maximum transmission span achieved was based on the red LED output. The links were fully tested for the quality of transmission using the standard test cards for video and audio signals. Add-itional information such as time information or the name of the song or video in multi-channel applications could be added to both audio and video signals. The proposed system is attractive for home entertainment application, museums, galleries, etc.
6. Conclusions
A visible light communication system for transmission of audio and video signals employing visible LEDs was presented. The S/PDIF formatted audio signal is digitized and used to intensity-modulate white illumination LEDs. Simultaneously, the analog video signal was transmitted using PWM via red illumination LEDs. The transmission and signal recovery were successful at the transmission distance of 50 cm without optical filters. The system quality was assessed using standard test signals for both links as well as by viewing the video signal and listening to the audio signal. It is expected that the proposed system could be adopted for a number of applications where high-quality sound and vision are required