I didn’t build this scanner – this one was made in Toronto by a company called Geonics. But I’ve made similar equipment. This one operates at 14.5kHz, which is conveniently inside the human audio frequency range, so you can use off the shelf audio system components to cobble a similar system together. However, getting it right (calibrations and such) is the tricky part. Half the reason I was collecting this test data was to verify that I could use the instrument (we just bought it), and that the calibrations were sane.

It streams data out over a Bluetooth serial port. So it’s pretty easy to log it actually. We use a windows program on a field ruggedized table – it logs the raw data with timestamp and GPS position. But I could write a python script to do it, so the software isn’t that advanced :)

Later I pull it into QGIS (open source and pretty amazing), and make a heat map. The background imagery is pulled from Google Earth.

Geophysical equipment tends to be quite simple but also quite expensive. It costs a lot to make them – they’re mostly hand built. And they don’t sell in high volume, so to recoup your R&D costs, you set the price much higher than the components would dictate. Total cost of components in this unit would be something like $2k (excluding the tablet), but it sells for $30k. The manufacturer will be lucky to sell a half dozen globally each year, so most of the cost is in the salary of the technicians and engineers manually building them.

Going back to the audio components analogy – imagine them as high end guitars and amplifiers, hand assembled. Hell, much of the unit I used here is actually made out of wood (for it’s thermal properties, and electrical resistance).

Blurry photo of the unit from my testing. Weighs about the same as a guitar. And a bunch of dials on top too… ;)