Shunting Radios/Comfort Tone

We can provide radios with a shunting facility (comfort tone) for control of trains (shunters and or RRV)The operator simply gives the instruction to move, having had it confirmed back to him he gives the instruction to move and simply holds down the button controlling the shunting facility (broken tone) and when he requires the train to stop simply gives the command to stop stop. Should for any reason the train driver lose the signal (out of range, faulty radio, or controller takes finger off the button) the train driver would have been instructed to stop immediately.