Underwater GPS

[Buliwyf]

You accelerated when you entered the current. Now in the current you're not. But it hasn't felt you decelerate either. So it knows you're still traveling at the speed and direction you accelerated to earlier.

Drones can find their way home, without GPS, on a windy day. This is no different, wind is similar to current. A cruise missile takes a GPS reading at it's convenience, but relies mostly on inertial guidance until the point it's allowed to go active.

Yeah, it works. It works really well. I've seen plenty of this tech. Packaging it into a diver application is the catch. I'd put the sensor unit on the tank, not on the person. Then I'd stipulate that it only works on tanks HP100 or heavier. The less wiggling around the better.

If this thing has a good battery, you can get your GPS fix at the dock. Then you'd only have to set a waypoint where you jumped in, and let it know you want to go back to the boat, not the dock.

 

[NAM001]

I looked up underwater /diver navigation... there seems to be a lot of systems and all look very expensive

 

[emoreira]

Yup. There's nothing magical or particularly complex about inertial navigation, it's just challenging engineering to do it in a relatively small package at a price that divers will pay. If you stay at the surface for 30 sec or so for the gps to pick up your drift, before shifting to inertial mode under the water, that should be enough to get it initialized properly. That is, assuming they design the software well...

In fact you do not need to know where you are in the world, but you need to define the starting point to be able to return to that point. This is the example being discussed, you are entering to the water from an anchored boat and you want to return to it. The INS needs to track your movements related to the starting point, to be able to return to it.
As seen in the pics posted, the device is splitted in two units. The tracking device itself, which should be mounted in a part of your body that is more statical (for example attached to the tank or BCD) and a display unit attached to your wrist, like an Air Integrated PDC does with the gas pressure.
Ariadna people say that the device has a 2% accuracy. Suppose that you are diving from a 10 meters long dive boat.
If this device can take you back to the boat in a range of 20 meters after having dived 1000 meters, it has an incredible accuracy.

 

[AlekDikarev]

Hi everybody,

We've build true underwater GPS, no promises - just real-world devices:

Presenting RedWAVE, a ready and available underwater GPS system