Patent ID: 7050775

Claim:
In a communications system, a communication unit to transmit and receive information signals within said system comprising: a transmission section to transmit an information signal in the form of radio signals to at least one other communication unit within said system; a receiving section to receive said information signal in the form of radio signals from at least one other communication unit within said system; and a processor to control communication unit operation to transmit said information signal and receive incoming signals to determine the presence of and process said information signal; wherein said receiving section includes a synchronization circuit to detect a pre-arranged synchronization signal transmitted by said other unit and trigger said processor to initiate reception of an incoming information signal from that other unit in response to said detection, said synchronization signal being transmitted by said other unit independently of said information signal and including a sequence of at least one frequency signal with each frequency signal of a particular corresponding frequency; wherein said information signal is generated and transmitted in accordance with a first scheme, and said at least one frequency signal is generated and transmitted in accordance with a second different scheme.