CNN CNN Newsroom April 5, 2014 15:23:00
>> yes. the company manufacturers these beacons for the global market or voice and data recorders for aviation as well as submarine application. youre exactly right in terms of installation. the way these devices operate, they are designed to automatically begin emmiim emi ping at 37.5 kilohertz, one ping per second, when they are immersed in water. that ping will continue until the device is recovered for a period of 30 days. possibly a bit more depending on the condition and age of the battery...
Source: archive.org