NIST scientists have figured out that Morse code may get through poor
transmission conditions when voice does not.

"...first responders may be able to receive and see simple patterns�like
Morse code�from a survivor repeatedly turning a radio or phone on and off,
in cases where the signal was too weak to receive audible voice messages."

http://www.nist.gov/public_affairs/r...ion_dcconv.htm

73 de Jim, N2EY