Encoded data may be generated and transmitted from one computing device to another via a network. The security device includes a carrier and a multilayer coating on the carrier. The cartridge has at least one aperture and preferably the radioisotope seeds and spacers are loaded around the periphery of a rotatable drum within the cartridge. The method comprises receiving a reference signal from a network node, , identifying at least one positioning subframe comprised within the received reference signal and performing measurement on the reference signal over the at least one identified positioning subframe. An optional door cleaning assembly comprises a rotational housing, a shaft disposed in the housing and a door receiving assembly rotatably disposed on the shaft and within the housing and securably receives the door and forms a fluid-tight seal between the door and the door receiving assembly.