A device main unit transmits a bus reset pulse to an antenna unit via a cable transmitting a television reception signal, a controller of the device main unit detects a response of a presence pulse to the bus reset pulse and displays the detection result. The transmission of the bus preset pulse and the reception of the presence pulse are performed by utilizing the existing communication interface with 1-Wire type interactive baseband communication system disposed to control a tunable radio frequency circuit provided for the antenna unit from the controller adopted thereto.