PURPOSE: To prevent a received pattern from being erroneously recognized by controlling the level of a timing pilot signal sent independently of a data signal to send a status signal.

CONSTITUTION: A transmission data of a channel A on a signal line 101 and a transmission data of a channel B on a signal line 102 are fed respectively to a coding circuit 1, where they are multiplexed. Then the 1st pilot signal used as a timing signal in a different frequency other than the data signal comprising the status signal of each channel and the 2nd pilot signal used as a carrier pilot signal are sent. The 1st pilot signal is set to one of plural prescribed levels in response to the combination of the status signals of each channel and the 2nd pilot signal is set to a prescribed level and set to the transmission means together with the data signal. A reception section detects the level fluctuation of the 2nd pilot signal to suppress the level fluctuation in the transmission means by the internal gain control, the 1st pilot signal level is detected to discriminate the status signal of each channel.