Abstract: In order to solve the problem of the complexity of indoor positioning system and unsatisfactory response

time， this paper uses Fourier transform to process square-wave modulated optical signals to reduce the response

time，and optimizes the reflection effect of optical signals in the transmission process， then establishes a positioning

system model with high accuracy and fast response time.Based on the function describing the relation of light

intensity and distance， the correction of the incline plane has been founded which helps to solve the coordinates of　

the receiver.By applying the theory to the positioning device， the visible light positioning system with fast response

and high precision is finally realized.

Key words: indoor - positioning, fast Fourier transform, visible light, inclination improvement, squarewave modulation