Patent ID: 9681521
Date: 2017-06-13
CPC Classifications: H05B,Y02B

Claim:
1. A first lighting device comprising: an electromagnetic sensor operable to receive an electromagnetic signal from at least one other lighting device; an acoustic sensor operable to receive an acoustic signal from the other lighting device; and a signal processing module configured to determine a distance between the first lighting device and the other lighting device based on at least one of: a difference in arrival time of the acoustic signal received from the other light device compared with that of the electromagnetic signal received from the other light device and a difference in intensity of the acoustic signal received from the other light device compared with that of the intensity of the electromagnetic signal received from the other light device, wherein the signal processing module is configured to perform the determination of said distance on condition of detecting a code in the acoustic signal from the other lighting device that corresponds to a code in the electromagnetic signal from the other lighting device.