Abstract
Among various technologies for wireless communication, Bluetooth and Wi-Fi used for long-range and Radio frequency applications widely used for short-range communication. But these spectrums are restricted by range and noise handling. Optical Communication using visual light is becoming more researched technology because of low cost and easy configurable LEDs. These LEDs are used in places like universities, airports, malls, and subways. So, we can use these LEDs to broadcast signals that carry information. But we need some receiver which can demodulate these optical signals and generate the intended message. So, what can be the better choice than a smartphone? Around 2 billion users have a smartphone in the world today, and these smartphones are carrying good quality sensors and digital cameras that have rolling shutters mechanism. This project introduces the fundamental of the visual light system using a smartphone camera that has a rolling shutter camera mechanism. This project consists of 2 major modules: Transmitter and receiver. The transmitter module has Arduino with LED setup which uses pulse width modulation to transmit the optical signals. While capturing the image, it causes the color distortions and flickered image whenever the target is in motion, or the camera is not stable enough. To solve this issue, we have worked on various methods to enhance calibration and stabilization of the captured frame using OpenCV and rolling shutter effect and how the relationship between them works. For the rolling shutter effect, I'll explain how to use CMOS sensors for frame to capture the data row by row. We have also conducted a few experiments to implement the mechanism and verify my findings.