the tetra system works on a pulse frequency of 17.6Hz, with our beta brain waves being around 13Hz to 20Hz. the tetra system is right in the middle, that is what worrying people. as for the TV transmitters, the antenna is right up in the air not under a pen length from your brain as with the moblie tetra system. oh i almost forgot they down the power output of the TV tx before ANY work is done on the mast. even if it low down!! Now im not saying it is tetra is dangerous or not, but they need to say they dont fully know how the system could act on the human body.