On the subject of exposure to TETRA signals, MTHR completed three well-designed studies, none of which "provided any evidence that TETRA signals produce specific adverse effects in those exposed to them." With regard to the importance of signal modulation - i.e., whether there are specific effects from the modulations of radio signals that are different from those of the carrier frequency alone - MTHR found "a substantial body of evidence that modulation does not play a significant role in the interaction of radiofrequency fields with biological systems."
A press release about the report can be found here
. The full text of the report can be found here