My man Alan Gowa does it again and found this very interesting and informative thread over on The Gear Page. Basically the thread and the article that is linked in the thread talks about the 700MHz “white spaces” frequency range.
Getting right to the point in a nutshell with an excerpt from the article ” The entertainment industry, sadly, can no longer use the 700 MHz band for wireless devices because of the risk of interfering with emergency responders’ communications, or other new wireless services. In January of 2010 the FCC issued a notice that as of June 12, 2010 any wireless microphone equipment that uses frequencies between 698 MHz and 806 MHz is prohibited in the United States”. There is a lot of very interesting info in this article and worth a read..!!