| 摘要 |
PROBLEM TO BE SOLVED: To provide a light data modulator-demodulator for stably performing light communication at high speed from short-distance to long-distance without increasing neither a circuit scale nor an operation load.SOLUTION: A light data demodulator includes: an A/D conversion part for A/D-converting a reception signal received by a photodetector by a local oscillation clock with a multiplication frequency of a carrier frequency; a phase detection part for performing a product-sum operation between the A/D-converted reception signal and an orthogonal reference signal in synchronization with the local oscillation clock, and calculating a phase, based on a product-sum operation result; a phase setting part for setting the phase to be a reference phase when the phase calculated by the phase detection part continues by a predetermined symbol number; a phase difference correction part for calculating an arithmetic mean value of the phase of symbols, which corresponds to the reference phase set by the phase setting part, and correcting a relative phase difference between the reference phase and the phase of the symbols, based on the calculated arithmetic mean value; and a data demodulation part for demodulating data, based on a relative phase corrected by the phase difference correction part. |
