This paper describes the optical design of a two-lens visible light communication system to reduce background noise. The system is composed of an image sensor, a receiving element, and control software. The selected area for the receiving element was calculated by considering the chip size, the focal length of the lens, and the pitch between the image sensor and the receiving element on the PCB board. The communication length is expected to be proportional to the focal length of the lens. LED sources were modulated by subcarrier 4-bit pulse position modulation of visible light ID at the carrier frequency of 28.8 kHz. The communication length of the system using a commercialized high-sensitivity phototransistor was measured at up to 16.5 m for a focal length of 12 mm. In the phototransistor array system, the brightness and illuminant size from the image sensor were used to identify the signal source. The system separates the data from multiple signal sources by selecting an arbitrary receiving element.
ASJC Scopus subject areas
- Signal Processing
- Physics and Astronomy(all)
- Computer Networks and Communications
- Electrical and Electronic Engineering
- Applied Mathematics