Yingming Gao

A short-range optical wireless transmission method based on LED

As to electromagnetic wave interfere and only one to one transmission problem of Bluetooth, a short-range LED optical wireless transmission method is proposed to be complementary technology in this paper. Furthermore achieved image transmission through this method. The system makes C52 to be the mater controller, transmitter got data from terminals by USB and sends modulated signals with LED. Optical signal is detected by PD, through amplified, filtered with shaping wave from, and demodulated on receiver. Then send to terminals like PC and reverted back to original image. Analysis the performance from peak power and average power, power consumption of transmitter, relationship of bit error rate and modulation mode, and influence of ambient light, respectively. The results shows that image can be received accurately which uses this method. The most distant transmission distance can get to 1m with transmitter LED source of 1w, and the transfer rate is 14.4Kbit/s with OOK modulation mode on stabilization system, the ambient light effect little to LED transmission system in normal light environment. The method is a convenient to carry LED wireless short range transmission for mobile transmission equipment as a supplement of Bluetooth short-range transmission for its ISM band interfere, and the analysis method in this paper can be a reference for other similar systems. It also proves the system is feasibility for next study.

Study on the color merging of white light and transmission properties of wavelength division multiplexing visible light communication system based on RGB light-emitting diodes

Abstract. Visible light communication (VLC) systems have an advantage for simultaneously achieving communication and illumination. To strengthen the performance of VLC by using RGB light-emitting diodes (LEDs) while meeting the lighting requirements, the channel capacity and the transmission capability of the system are improved by utilizing the wavelength division multiplexing (WDM) technology. We make the chromaticity of the merged white light suitable for human eyes by the experiment. The parameters of merged white light based on RGB LEDs and the merging ratio data measured by the experiment are given. Hence, we study and analyze the eye diagrams and bit error rate (BER) of different optical channels. The simulation results show that maximum transmission rate of the output signal is up to 3.3  Gbit/s, and the BER is less than 10−5 with a transmission distance of 2.5 m while meeting standard illumination requirements.

A design of low cost illuminometer with multiple functions

This paper designed a novel illuminometer with low price and multiple functions compared with most commercial illuminometer. In addition to illumination measurement, the meter can also measure temperature and humidity used for measuring its working environment, even conduct wireless communication each other. The meter circuit design was provided, such as interface of light sensor to microcontroller respectively. A data Tx/Rx method of communication unit using its nIRQ pin was presented, which do Tx/Rx according to content of status register in interrupt service routine. Program flow char of driving digitrons to do dynamic display was presented. Finally, measurement result comparison was done with two commercial illumination meter.