Patent ID: 8406690

Claim:
A system for transmitting data between a first component ( 30 ) and a second component ( 31 ) which rotates relative to the first component, the system comprising: a first coupling element ( 32 ) of limited angular extent mounted to the first component, and a second coupling element ( 33 ) of limited angular extent mounted to the second component, the first and second coupling elements coming into angular alignment once per revolution of the second component relative to the first component, and a first transceiver ( 34 ) connected to the first coupling element, and a second transceiver ( 35 ) connected to the second coupling element, wherein at least one of the first and second transceivers is configured to detect the angular alignment of the first and second coupling elements, and are further configured to transmit data between the first and second transceivers via the first and second coupling elements when the angular alignment is detected; and wherein one of the transceivers is a master transceiver and the other is a slave transceiver, the master transceiver repeatedly driving its respective coupling element with a call signal, and the slave transceiver monitoring its respective coupling element for receipt of the call signal, whereby data is transmitted between the transceivers after the slave transceiver receives the call signal.