The receiver employs a commercially available Si PIN
(Hamamatsu S6968) photodiode for optical to electrical
conversion with 150 mm2
effective active area, 14mm active
area size and 35° half angle. It receives optical signal which is
sent to a low pass filter followed by a custom amplifier for
recovery
detection (DD) scheme is chosen for the widely reception in
VLC research.. A decision circuit is used as a single threshold
voltage comparator to achieve the signal decision with a
reference voltage level to obtain the original signal. The TTL
signal after decision is sent to FT230 to achieve the
conversion from TTL signal to USB serial signal. The
transceiver design is shown in Fig 2.