Sounder(Fish-Finder) as a Underground Radar

[Amona]

Hi people

Question: I heard before people that are using sounder(Fish-Finder) to detect buried object underground, is it possible?

Amona

[Dinkydick]

I don't know about underground but I have detected objects under the bottom of
lakes and rivers using a depth sounder.

Many years ago I had a survey grade depth sounder (made by Bludworth Model
NK-2) which would penetrate the bottom at up to 10 feet. I should add that this
equipment ran with tubes and was a very heavy piece of equipment. The transducer
consisted of two elements which were about 14-inches in diameter and operated at
14.7Kilohertz (14700 cycles/Hertz). Their operation was based on the magnetostrictive
principle not the piezoelectric types used today in modern sounders. The low
frequency permitted the transmitted sound to penetrate the bottom which showed
recordings below the bottom. I don't have the NK-2 any more but I do have a NK-6
which was a later model of the same sounder. And I do have the transducers.

At some later date (if I live long enough) I intend to build a sub bottom profiler using
the transducers.

As far as I know I don't know of any manufacturer which makes depth sounders which
operate at this low frequency.

FWIW I was an Electronics Technician First Class (sonar specialist) during the Korean
war. I was very familiar with tube type equipment.

I am open for questions and help.

Dinkydick

[stevemc]

A regular boat fish finder sonar will not work out of water. The only way, would be if the ground was submerged, and the transducer was in the water. The fish finder will see the air as impenatrable. Like the air bladder on a fish, or a scuba diver. On a color sounder they(fish with air bladder) show up as a different color than bottom, showing fish laying on the bottom. Sharks dont have an air bladder and show up as a different color. Same with jellyfish. Sounds like the sonar that Dinkydick has is quite nice. It should be good for stuff buried under sand.