Patent ID: 9077456
Filing Date: 2015-07-07
Classification: H04B

Abstract:
1. A visible light receiving device comprising: a first conversion unit configured to receive visible light and generate a voltage signal corresponding to an amount of the visible light, the visible light having an intensity that varies depending on modulated signals which have a modulated part in each of symbol time periods; an amplification unit configured to cut a DC component in the voltage signal and amplify an AC component in the voltage signal, thereby generating an amplified voltage signal; and a processing unit configured to process the amplified voltage signal provided from the amplification unit to generate demodulated signals of the modulated signals, wherein the processing unit includes: a second conversion unit configured to perform, for each of sampling time durations, analog-to-digital (AD) conversion on the amplified voltage signal provided from the amplification unit into an AD-converted value, eventually generating a plurality of AD-converted values; a first calculation unit configured to calculate a difference between each pair among the AD-converted values to eventually generate a plurality of difference digital values; a second calculation unit configured to calculate a positive reference value and a negative reference value based on a peak value among the difference digital values; a detection unit configured to detect (a) at least one rising point from when successive difference digital values each greater than the positive reference value appear among the difference digital values, and (b) at least one falling point from when successive difference digital values each smaller than the negative reference value appear among the difference digital values; a third calculation unit configured to calculate a first sample period and a second sample period, the first sample period being a period from a target rising point to a falling point detected immediately subsequent to the target rising point, and the second sample period being a period from the falling point to another rising point detected immediately subsequent to the falling point; and a fourth calculation unit configured to calculate a corresponding one of the demodulated signals for each of the symbol time periods, based on the first sample period and the second sample period which appear alongside each other in a temporal sequence in the each of the symbol time periods.