The wobbly voice barely penetrated the snowstorm of static. It took an ear pressed close to the speakers to make out a faint murmur."CQ, CQ," the voice said, before repeating a call sign, a set of letters that identified the radio operator and his or her location.Listening on headphones, Tom Schaefer spun a knob on the front of a massive digital radio display, adjusting frequencies and checking the position of a satellite antenna. He struggled to hear where the voice was calling from."I can pick up a cellphone and talk to any of these other operators. That's easy," Schaefer said. "I can get online and I can send out a tweet, and that's easy. But when you talk to somebody like this, and there's nothing between you and them but empty space, that's magic."Schaefer was one of about 20 amateur radio operators who gathered Saturday under a canopy at the Bay Pines VA Medical Center for a nationwide "field day" demonstrating the potential of emergency radio communications. The annual event, organized by the American Radio Relay League, brings together radio enthusiasts, known as "hams," from throughout the country.For 24 hours, local clubs, like the St. Petersburg Amateur Radio Club (SPARC) who assembled at Bay Pines, worked the airwaves to make contact with each other.It would be easy to dismiss amateur radio as an obscure hobby centered around old technology. But when computers crash, and cellphones die, amateur radio offers a technological safety net.In the wake of hurricanes or other disasters, these radio operators deploy their antennas to help guide communities away from harm. Last year, when a tornado touched down near Pass-a-Grille, it was a local ham who radioed the National Weather Service, said SPARC president Bob Wanek. "That's really the exercise here," Wanek said. "To prove to people, and to ourselves, that we can do it."On Saturday, Schaefer and others worked the satellite communications. Others tapped out "CQ" calls in Morse code. Others called out over microphones, looking to connect with anyone who might be tuned in at that exact frequency at that exact moment.By late Saturday afternoon, SPARC members had exchanged a half-dozen call signs with other hams throughout North America. They reached people in Alabama, Kentucky, Illinois and as far away as Ontario.Across the bay, about 50 other hams with the Tampa Amateur Radio Club tested their own emergency capabilities.Among them, 12-year-old Carlos Hernandez had never operated an amateur radio before. But that didn't stop him from learning the knobs and buttons and talking with someone in Venezuela. "I speak Spanish, so I could understand them," Hernandez said, as he got ready to place his second call of the day, this time to New Jersey. "I like talking to people around the world."