Patent ID: 7356041

Claim:
A system for transmitting signals on a plurality of transmission channels, the system comprising: a master unit configured to detect a vacant channel among a plurality of transmission channels and to transmit a signal on the vacant channel; and at least one slave unit configured to scan the channels for the transmitted signal, the signal transmitted by the master unit defining a preamble having a length corresponding at least to the time required for the at least one slave unit to test the channels for the transmitted signal, the preamble having a predefined characteristic with system specific information indicating to the slave unit that the transmitted signal is a message originating from a master unit related to the same system, wherein the at least one slave unit is further configured to, when having detected the predefined characteristic, interrupt the scanning and test the message received via said channel for an address, and wherein said at least one slave unit further is configured to acknowledge receipt of the correctly addressed signal by transmitting a response signal to the master unit via said channel.