Linear MegaCode Garage Door SMDRG Digital Gate Receiver Linear MegaCode digital gate receiver. The MegaCode series of digital receivers are wireless radio controls designed for use with automatic gate openers or garage door operators MegaCode receivers and transmitters do not contain a typical "coding switch". Each transmitter is pre-set at the factory to a unique code. Includes receiver, "F" connector, whip antenna, and mounting bracket.