Using EM technology to find treasure

I'm not sure what EM tech is but the guys in Florida in the USA are playing with it to locate gold and silver treasure from shipwrecks.
They are hoping to find silver bars and coins up to six feet under the mud and have done tests that show a pulse metal detector is capable of locating a TEST siver bar at two feet deep but the EM coil can see it at six feet !
From what I've seen this is a boat towed system and has a colour screen read out very much like a high quality fish finder.

I have used magnetometers to locate deep buried objects underwater but they will not find gold or silver only iron objects, EM will locate all of these.

Could this be similar to minelabs new technology ????

Regards snapper

I've read the patents for this thing,,,,,,as much as I can figure these things out,,,,,,,,,,and I reckon you could use Electro-Magnetics in a PI inductive/conductive detector,,,,,,,,,,,but inversely. Instead of using EM to search for a target, it's used to cancel out the background that you don't want to see (hear).

!!!!!!

Consider if you will, the electronics sense the magnetic load of the soil, much as ground balancing works in older detectors but with a "thousand times" more sensitivity than the general use of GB today.

It can then sense EACH tiny little piece of magnetics than can cause "background clutter noise" and cancel out each little bit of EM interference. After which you get the signal in yer ears,,,,,,,,,,,,,noise free.

A bit like these radio telescopes can pick out a signal from a star "75 trillion light years from Earth" 'cos it cancels every single bit of all the garbage that will interfere with that one signal that they're looking for.

Just saying,,,,,,,But WTF do I know, I was a truck mechanic,,,,,,