Tens of thousands of amateur radio operators took to the sound waves Saturday as part of the Annual Amateur Radio Relay League Field Day.
Several East Tennessee groups participated, including the Radio Amateur Club of Knoxville.
The goal is to see which league can make contact with the greatest number of operators nationwide.
But for RACK, it's also a training exercise.
"When normal communication goes out, ham radio still works. That's what we're proving here today," says member Dave Garner.
Powered by the same voltage as a car battery and requiring only a radio and an antennae to work, ham radio technology is both a hobby and a valuable tool in crisis.
"Hurricane Katrina, the tornadoes in Tuscaloosa. Normal communication during those times when down. Ham radio did not," explains Garner.
RACK says in past year's they've heard from about 600 operators across the nation during the 24 hour event.