Augmenting a Smartphone Camera with a Telephoto Lens for Enhanced LED-to-Camera Communication

In LED-to-Smartphone Camera communication, the camera detects the status of the light source (ON or OFF) in each frame to receive information. If the light source is modulated faster than a single frame duration, there are multiple white & dark stripes corresponding to the transmitted information bits. Further, the receiver’s region of interest in LED-to-Smartphone Camera communication is limited by the size of the light source in the frame in terms of the number of pixels. As the distance between the LED and the camera increases, the light source does not cover the whole frame, resulting in a significant amount of data loss. Therefore, LED-to-Smartphone Camera communication is limited by distance, making it difficult to transmit data from several meters away. On the other hand, there is a loss of data even at relatively short ranges due to small region of interest, especially for tiny light sources. In this work, we enhance the smartphone camera with a telephoto lens that provides optical zoom on the light source and increases the region of interest. The optical zoom from a telephoto lens helps the user focus on the light source and reduces data loss. We compare the data transfer rate with and without a telephoto lens at short distances (15-80 cm). The initial results show that a telephoto lens improves the data transfer rate at short distances and also expands the possible range for LED-to-Smartphone Camera links.