Patent ID: 8520706

Claim:
A transmitting and receiving method for transmitting a data string signal to a primary system and a backup system and for receiving the data string signal multiplexed by a predetermined cycle period from the primary system and the backup system, comprising the steps of: generating a first periodic signal having a predetermined cycle period and a second periodic signal having a longer cycle period than said first periodic signal; and synchronizing said data string signal with said first periodic signal, and multiplexing said data string signal which has been synchronized with said first periodic signal by a cycle period which is synchronized with said second periodic signal to transmit said multiplexed data string signal to said primary system and said backup system; performing synchronous processing of received signals received from said primary system and said backup system; performing processing for aligning each phase of received signals which are received from said primary system and said backup system and on which said synchronous processing has been performed with a phase of said predetermined cycle period respectively; and switching between a received signal which is received from said primary system and on which said phase alignment processing has been performed and a received signal which is received from said backup system and on which said phase alignment processing has been performed, wherein said synchronous processing is synchronous processing for synchronizing received signals received from said primary system and said backup system with a first periodic signal individually and synchronizing received signals of said primary system and said backup system which have been synchronized with said first periodic signal with a second periodic signal having a longer cycle period than said first periodic signal individually, and wherein said synchronous processing with said second periodic signal synchronizes positions of an overhead area and a payload area of a received signal.