Logic Trunked Radio (LTR) is a system developed in the late 1970s by the E. F. Johnson Company. LTR is distinguished from some other common Trunked Radio Systems in that it does not have a dedicated control channel. Each repeater has its own controller and all of these controllers are coordinated together. Even though each controller monitors its own channel, one of the channel controllers is assigned to be a master and all the other controllers report to it.