How to Build a Simple Underwater Radiolocation System
- Ken Smith (updated 13 April 2011)
In 2001 I was involved with a mapping project at Tank Cave near Mt Gambier in South Australia. Tank Cave has only one small entrance and is almost completely underwater. A complex array of passages extends to over one kilometre from the entrance. It was clear that a radiolocation system, combined with above ground measurements by differential GPS, would allow more accurate surveys to be made.
The "Pinger" radiolocation transmitters were designed to be small and easy to carry by divers through narrow passages. They were designed to float against the roof and be self levelling. This meant that they could be quickly deployed in small passages where rapid silting was a problem.
The following article, written in 2001, describes the basics of the Pinger system;
The Pingers have also been put to use in the Bahamashttp://www.bahamascaves.com/blueholesconservation/caveradiolocationproj.html
I will now try and describe the technical details of the Pinger system. Much of the development took place by experimentation and is recorded by me on scraps of paper! I will update the following document as I get the technical information in a presentable form. The electronics is quite simple. I think the success of the Pinger comes from the use of laminated mu-metal cores for both the transmit and receive coils.
Here are links to my construction document which includes circuit diagrams and data sheets on the ICs used. Good Luck! and please contact me if you have any questions.
MORE INFORMATION 7 July 2008
Please feel free to use information I have provided to build your own radiolocation system for personal use. If you want to use ideas described here to manufacture systems for commercial sale then please talk to me first. The usual disclaimer applies in that anything you choose to do is at your risk and I can't guarantee the success of anything that you construct.