ThinkDefence reports L3 is resurrecting an old idea to extend the horizon distance for surface vessels. Their “virtual mast” puts sensors at high altitude without the need for a helicopter or UAV. Popular Science has a bit more detail, reporting that the proposed system could fly as high 5,000 feet. Sensors at that altitude would have a radar and visual horizon of 76 nautical miles.
Not sure how they would warn off air traffic that might otherwise hit the cable or the autogyro.
Historical Note: During WWII German U-boats used a similar unpowered tethered autogyro to take a lookout aloft, but their altitude was much more limited.