An important feature for highway advisory radio (HAR) systems is to vary the power level of the transmitter output. This will increase or decrease the coverage area accordingly. 

The TCM-1 Transmitter Control Module (when used in conjunction with the TXM4 transmitter) allows the power to be set to from 0.1 watts up to 30.0 watts. 

The TCM-1 Module is controlled from the MH Corbin R1500 or CAM-1 recorder/player, which in turn can be controlled remotely using Platinum software.