The U.S. Coast Guard is adding a satellite component to a new digital communications system it currently is deploying to receive distress signals from boaters within 20 miles of U.S. shorelines.

The system, dubbed Rescue 21, is intended mainly to relay calls for assistance from distressed boaters to the Coast Guard’s command centers. Rescue 21, being installed under a contract with General Dynamics, is replacing an older system that relies on analog radios and towers for communications.

“We have a system of high sites or antennas along the cost that pick up that [distress] signal,” Lt. Cmdr. Thomas Norton, commander of the Coast Guard’s Project Resident Office, told Satellite News. “That signal is then relayed back to a central command center in the region” where the distress call originates from.

Under normal conditions, the approximately 460 antennas that cover the shoreline of the United States, Guam and Puerto Rico in the Rescue 21 system will operate using terrestrial communications technology. However, in the event of a natural or man-made disaster that disrupts an antenna in the communications network, the Coast Guard can establish a satellite link to fill in any holes while crews get the terrestrial antenna back online.

“To replace that hole in our coverage, we have a portable antenna tower that we pull behind a truck,” Norton said. “In the truck, there are radios as well as a satellite dish. We tow the portable antenna to the site where the tower we had there before is either down or isn’t working. It has its own generator, its own antenna tower for the VHF communications and its own radios so we can pick up the signal at this local site from the boater that is in distress. In order for our watch standers to hear that back at the remote site, we need a means to get that signal from that local site back to the communication center. The way we do that is via the satellite link.”

Norton said the Coast Guard has a number of the mobile towers strategically deployed across the United States “so that within 24 hours, we can have a mobile antenna on site at any of the antenna sites and we can replace a downed antenna.”

–Gregory Twachtman

(Lt. Cmdr. Thomas Norton, U.S. Coast Guard, thomas.a.norton@uscg.mil)