A method of updating a content detection module includes obtaining content detection data, and transmitting the content detection data to a content detection module, wherein the transmitting is performed not in response to a request from the content detection module. A method of sending content detection data includes obtaining content detection data, selecting an update station from a plurality of update stations, and sending the, content detection data to the selected update station. A method of building a content detection system includes establishing a first communication link between a central station and an update station, the central station configured to transmit content detection data to the update station, and establishing a second communication link between the update station and a content detection module.