A positioning system and method for determining a coordinate of an object may comprise a positioning transmitter system and a positioning receiver system. The positioning transmitter system includes at least four light sources and a master anchor to modulate the light sources to emit modulated light signals each having a modulation frequency. The positioning receiver system comprises a lens to focus the light signals onto an optical sensor, an envelope detector to receive a signal from the optical sensors and provide output signals corresponding to the modulation frequency, and positioning detection circuitry. The positioning detection circuitry receives calibration data; determines at least four phase difference of arrival (PDOA) pairs based on the output signals from the envelope detector; determines at least four phase corrected PDOA pairs based on the calibration data and the PDOA pairs; determines at least four linear distance differences based on the phase corrected PDOA pairs; and determines the coordinate of the object based on the linear distance differences and the calibration data.