Methods and systems to determine at multi-dimensional coordinates of an object based on propagation delay differences of multiple signals received from the object by each of a plurality of sensors. The signals may include optical signals in a human visible spectrum, which may be amplitude modulated with corresponding frequency tones. An envelope may be detected with respect to each of the sensors, and signals within each envelope may be separated. A phase difference of arrival may be determined for each of the signals, based on a difference in propagation delay times of the signal with respect to multiple sensors. The phase differences of arrival may be converted to corresponding distance differences between a corresponding transmitter and the corresponding sensors. A linear distance and a perpendicular offset distance may be determined from a combination the distance differences, a distance between the corresponding transmitters, and a distance between the corresponding sensors.