ROBOTIC submarines have always had trouble when it comes to picking up GPS signals and communicating with their operators. That's because radio signals do not travel far underwater. If the submarines do not surface regularly in order to check their position, they run the risk of drifting off-course.
This problem could now be solved, thanks to a wing-like antenna that piggybacks on small submarines. The antenna ascends to the surface on a tether as and when needed, enabling satellite communications, including GPS readings. It can even carry a camera to serve as a kind of periscope for the sub's controller.
People-carrying submarines have long been able to raise communications equipment to the surface while staying submerged. Jake Piskura, a mechanical engineer who designed and built the new antenna at Brooke Ocean Technology in New Bedford, Massachusetts, says the dramatic reduction in the size and power requirements of GPS and communications chips in recent years is making a similar feat possible for small robot submarines with limited supplies of power.
Robert Headrick of the US Office of Naval Research in Arlington, Virginia, which funded Piskura's work, says the US navy is interested in using autonomous subs to patrol harbours, keeping watch for seaborne attacks. The tethered antenna would let these subs stay in constant contact while remaining hidden.
