Receiver and method of receiving an encrypted communication

摘要

A receiver may receive an encrypted communication and decrypt (201) the encrypted communication in accordance with a decryption process. The resulting decrypted signal is subsequently output (203). Synchronisation messages comprising a synchronisation value and a synchronisation message verification value are received (205) where the verification value is optionally dependent on a transmit time of the synchronisation message. The receiver then determines (207) the validity of the verification value in response to a real time clock of the receiver. If the result is a valid verification value, the decryption process is synchronised (209) in response to the synchronisation value. Otherwise the receiver enters a fall back mode of operation (211). However, in the fall back mode of operation (211) the receiver continues to decrypt and output the signal thereby allowing signals to be received despite checksum errors occurring. The invention may facilitate interoperation between communication units comprising real time clocks and communication units not comprising real time clocks.