Strong ambient light and the resultant photoelectric conversion saturation of an avalanche photo diode (APD) may signficantly deteriorate the received signal in visible light communication (VLC) systems. Hence. in this paper we characterize the signal received from an APD under strong ambient light based on our experimental data. To illustrate the phenomenon of APD saturation. https://foldlyers.shop/product-category/monocrystalline-panels/