Affordable Ground-Penetrating Radar

While you might think of radar pointing toward the skies, applications for radar have found their way underground as well. Ground-penetrating radar (GPR) is a tool that sends signals into the earth and measures their return to make determinations about what’s buried underground in much the same way that distant aircraft can be located or identified by looking for radar reflections. This technology can also be built with a few common items now for a relatively small cost.

This is a project from [Mirel] who built the system around a Arduino Mega 2560 and antipodal Vivaldi antennas, a type of directional antenna. Everything is mounted into a small cart that can be rolled along the ground. A switch attached to the wheels triggers the radar at regular intervals as it rolls, and the radar emits a signal and listens to reflections at each point. It operates at a frequency range from 323 MHz to 910 MHz, and a small graph of what it “sees” is displayed on an LCD screen that is paired to the Arduino.

Using this tool allows you to see different densities of materials located underground, as well as their depths. This can be very handy when starting a large excavation project, detecting rock layers or underground utilities before digging. [Mirel] made all of the hardware and software open-source for this project, and if you’d like to see another take on GPR then head over to this project which involves a lot of technical discussion on how it works.

25 thoughts on “Affordable Ground-Penetrating Radar

  1. My mother has a weird spot on her lawn. In winter the snow melts in a perfect circle with a diameter of around 1.5 meters. If you stomp on it, it feels and sounds kind of hollow somewhere deep below. I probed the spot with a metal rod and the earth is ca 30 centimeter thick before there is something solid which feels a little like wood. The house was build 50 years ago and nobody knows whats underneath and I do not dare to open it… Maybe this project brings me a bit further without releasing the demons below, because 2020 is already bad enough.

    1. If I were to guess I would say an old covered up well. Might be worth checking out in more detail so whatever the wood is covering isn’t dangerous (as in a well) in case the wood has become weakened and gives way.

    2. It could be a well or a septic tank? Either way it would be a good idea to know what is there. I would be careful of stomping on it, if it is rotten wood, or cracked concrete, you do not want it collapsing under you.

    3. Baby Jessica? Is that you?

      Seriously, you are going about this entirely backwards. Do dig it up (carefully) and find out what it is but don’t ever stomp on it.

      If it turns out to be a well then… camera, light, long cord… find out what’s at the bottom! Isn’t it great that we live in a time where the equipment to do that is just a few bucks worth of eBay junk?!? Then seal it up good, so good that nobody is EVER going to fall in.

    4. You may want to leave that alone.
      50 years ago (1970) there were fuel tanks buried in yards. I have seen them used for oil furnaces and gas pumps for cars. They get old, rust, and leak. That could be a very expensive cleanup job. (Think about the cost of having the yard removed and remediated). I have heard of people just quietly unscrewing the fill tubes and covering it over with dirt and/or gravel. If it was bad off, they may have used a piece of wood.
      ymmv.

      1. Didn’t these people think of what would happen 20 or 30 years out, how dangerous that would be?

        My father handled putting away illegal dampers for the DEP in PA, and part of that was handling the decommissioning of underground gas tanks in old defunct gas stations.

        If you bury things like that underground with no sort of permanent shielding, it will dissolve and leach into the ground and the groundwater.

        It still amazes me what people got away with before things like the EPA and DEP. Of course now though, the EPA has been sadly gutted by a lunatic that doesn’t seem to mind if we go back to rivers catching fire again…

        1. Hey come on now, think about the upside.
          If you are fishing and the river is on fire, you get your fished cooked once it’s reeled in saving you time, — Ready to eat right off the line!

        2. “Didnโ€™t these people think of what would happen 20 or 30 years out, how dangerous that would be?”

          If people were use to thinking long term (climate change) then they would have marked on the deed where the utilities went. Guess what I get to do?

    5. If it is melting snow in winter, it is producing (a little) heat. Several possible things can do that 1. A fermenting septic tank, maybe still being filled by waste water. You may not know the plumbing of your house very well 2. If there is district heating in your area, an abandoned inspection well on a still used heating distribution pipe 3. Something quite strongly radioactive, which I really hope it isn’t (check radioactivity with a GM counter) but if you’re in Russia or the US you never know 4. A wastewater pipe leaking into the ground 5. Something I haven’t thought about.
      I would exclude an abandoned hydrocarbon (gas or heating fuel) tank because I really do not see how it could be slow-burning for so long, and this would need underground air so it would be really strange.

  2. Great build and video ! I would build it and test it out in the backyard….but I already know where all the bodies are buried. One more dumbass crosses me…and I am going to have to move. The neighbors love how nice my roses look though…..๐Ÿ˜„๐Ÿ˜„๐Ÿ˜„๐Ÿ˜„

  3. What I’ve wondered about is if modern electronics and signal processing applied to old BFO (Beat Frequency Oscillator ) metal detectors would be able to use the very good depth penetration of BFO while overcoming the problems with it that led to the development of TR (Transmit Receive) and other technologies.

    BFO was the original portable technology for electromagnetic detection of metal objects underground. Got its start for detecting landmines. By the 1960’s there were portable detectors with all the electronics (with vacuum tubes) small enough to fit into a single box on one end of a pole and the detector coil on the other end.

    Then came transistors, different coil designs, and different methods of managing and processing the field. BFO detectors were quickly relegated to “That obsolete old junk? Only good if you’re trying to find a buried pipe a few feet down. Totally useless for coinshooting or finding gold nuggets.”

    Instead of trying to develop ways to use the deep penetration of BFO by applying new developments in electronics, the metal detector industry just tossed it over its shoulder, chasing after shiny new toys that could barely pick up anything more than a few inches deep.

    Of course now there are detectors that can pretty well pinpoint small objects down to 18~20 inches and by processing the signals, with comparisons to stored samples from known targets, can tell the user what the target may be. But why not apply such tech to a method that could reach even deeper?

    1. Because, it’s still basically guessing, and you still have to dig it up, to really know. Metal detectors, only actually detect conductive materials. I’m comfortable digging holes about 8 inches deep most of the time. Easy work, easy to fill back in, not much of a mess. Seldom a complained about ‘plowing up’ the area. Sure, some places, neatness doesn’t matter. It’s a hobby, and you can take all the time you want. Most of the ‘treasure’, is where people frequent, past and present. Usually, they like you to leave the ground looking reasonably undisturbed.

  4. An experiment in high school electronics class (RIP, Mr. Scott) with BFOs did not, in the 1960s, include frequencies in the “323 MHz to 910 MHz” range. We did, however, create something that when hooked up to a speaker mooed exactly like a cow. Perhaps there’s a low-frequency GPR application – the C.O.W. (Comparator On Wheels) in the 10-million-meter range.

    1. Well, the cart design can be improved for sure – however the Vivaldi antenna should work line a blade, shooting directly into the ground. Interfence should be limited to the close proximity.

      1. Sorry if my comment was a little vague, my question was more because the FCC tends to regulate power output at certain frequencies and tends to be especially strict below 1 GHz. Is the radar transmitting in a ham band?

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