Gaihersburg, Md. (UPI) May 20, 2008 – The U.S. National Institute of Standards and Technology says it’s identified “sweet spot” frequencies capable of transmitting radio signals in tunnels.
Gaihersburg, Md. (UPI) May 20, 2008 – The U.S. National Institute of Standards and Technology says it’s identified “sweet spot” frequencies capable of transmitting radio signals in tunnels.