The signal sounded like crickets chirping, but the encoded message transmitted from the camp atop the frozen Arctic Ocean was music to the ears of the USS New Hampshire submarine crew. Using a digital "Deep Siren" tactical messaging system and a simpler underwater telephone, Raytheon is the latest low-frequency system trying to tackle the persistent challenge of communicating with submarines while they are traveling deep under the sea to avoid detection. Past systems have proven too complicated, and too expensive. The new system could revolutionize how military commanders stay in touch with submarines all over the world, allowing them to alert a submarine about an enemy ship on the surface or a new mission, without it needing to surface to periscope level, or 60 feet, where it could be detected by potential enemies. At present, submarines use an underwater phone to communicate with associates on top of the ice or with other submarines, but those devices are little more than tin cans on a string and work only at shorter distances. Submarines can also trail an antenna once they surface to periscope depth, or around 60 feet, but that makes them easier to detect. Improving the ability to communicate with submarines at any depth and longer distances is a huge step forward. Raytheon also offers a variant with buoys that can be quietly deployed by a submarine in its waste discharge, waiting to surface until the submarine is far away, and then relaying messages via satellite link.