A rotating control device for use with an offshore drilling unit, comprising: a body having a flange formed at an end thereof for coupling to a riser or blowout preventer stack of the offshore drilling unit; a seal assembly for receiving and sealing against a tubular; a bearing assembly for supporting rotation of the seal assembly relative to the body; a rotating section for mounting the seal assembly to the bearing assembly; and characterised in that the rotating control device further comprises a data system, comprising: a transmitting assembly disposed in a pocket formed in the rotating section and comprising: a sensing member for measuring a parameter of the RCD; an antenna located on at least a portion of a circumference of the rotating section; and a module operable to receive the parameter from the sensing member and to transmit the parameter as a radio frequency signal to a receiving assembly using the antenna; and the receiving assembly disposed in a pocket formed in the flange and comprising: an antenna operable to receive the RF signal and located adjacent to an inner surface of the flange; and an electronic system in communication with the receiving antenna and operable to communicate the parameter to the offshore drilling unit, wherein the transmitting antenna and the receiving antenna are spaced apart by a distance for accommodating transmission of the RF signal through a conductive liquid environment. a body having a flange formed at an end thereof for coupling to a riser or blowout preventer stack of the offshore drilling unit; a seal assembly for receiving and sealing against a tubular; a bearing assembly for supporting rotation of the seal assembly relative to the body; a rotating section for mounting the seal assembly to the bearing assembly; and characterised in that the rotating control device further comprises a data system, comprising: a transmitting assembly disposed in a pocket formed in the rotating section and comprising: a sensing member for measuring a parameter of the RCD; an antenna located on at least a portion of a circumference of the rotating section; and a module operable to receive the parameter from the sensing member and to transmit the parameter as a radio frequency signal to a receiving assembly using the antenna; and the receiving assembly disposed in a pocket formed in the flange and comprising: an antenna operable to receive the RF signal and located adjacent to an inner surface of the flange; and an electronic system in communication with the receiving antenna and operable to communicate the parameter to the offshore drilling unit, a transmitting assembly disposed in a pocket formed in the rotating section and comprising: a sensing member for measuring a parameter of the RCD; an antenna located on at least a portion of a circumference of the rotating section; and a module operable to receive the parameter from the sensing member and to transmit the parameter as a radio frequency signal to a receiving assembly using the antenna; and a sensing member for measuring a parameter of the RCD; an antenna located on at least a portion of a circumference of the rotating section; and a module operable to receive the parameter from the sensing member and to transmit the parameter as a radio frequency signal to a receiving assembly using the antenna; and the receiving assembly disposed in a pocket formed in the flange and comprising: an antenna operable to receive the RF signal and located adjacent to an inner surface of the flange; and an electronic system in communication with the receiving antenna and operable to communicate the parameter to the offshore drilling unit, an antenna operable to receive the RF signal and located adjacent to an inner surface of the flange; and an electronic system in communication with the receiving antenna and operable to communicate the parameter to the offshore drilling unit, wherein the transmitting antenna and the receiving antenna are spaced apart by a distance for accommodating transmission of the RF signal through a conductive liquid environment.