Archaeology Resistivity Meter

These photos are not really related, except to show an adapter plate. My overall construction of this unit is poor, it was just a quickly-hacked-together low-noise low-current (100mA maximum I think) portable fixed-voltage DC supply project that I only needed for one use-case, but I'd like to re-do it properly sometime. The dual-Lithium battery here is a lot smaller than NP-F, about the size of a 9V PP3 battery:

The photo below shows the adapter plate (these are sold individually, normally used to fit the battery to a universal charger):

Final unit, just banana sockets, LED, power switch and I can charge it from 9-12V using the DC jack on the side:

michaelkellett  Michael, to make life easier, why not use the above circuit as an input to a Pi 4 with an external SATA drive via the USB3 port?  AND BTW couple it with GPS info from a small GPS unit for the PI. Then when you are done with your survey you could remove the drive and put it on an external holder (about $40usd) mine is a Thermaltake BlackX 5G.

For S&Giggles you could put some sort of display keyboard so you can say START GRID #  or other things.

~~Cris

PS I was unaware about your probes making contact with the ground but that should not be an issue as you can drive the probes into the soil with a solenoid, or whatever. The  Operator could control the insertion and retraction of the probes via the display.

START  maybe enter grid number

get GPS (x, y) of the current grid

store X & Y

do {

get new gps

probe down

take reading

write data GRID, GPS, Reading

walk .5m  }( X +.5m < X+20m );

Tell the operator to do the next row.

if (Y + .5m < Y+ 20n) back to the do{ 

Well, it's a possibility, my plan would be to have a COM port over USB interface so it can certainly work with a lap top.

My experience of using a lap top in the field (mainly automotive) is largely bad - too big and heavy, run out of power, can't see screen in sunlight etc.

A little screen on the device is much nicer to work with but harder work to get it doing dood stuff.

Having the option to work via serial port expands options.

I try to write serial control protocols that can work internally between GUI and the core as well as between the core and a PC.

Serial over Bluetooth is an option as well.

Thanks for suggestions.

MK

documented with up to date project description, diagrams

Did someone say PowerPoint? : )

No? Oh well, now it's mentioned : ) I'm happy to put the block diagram so far into that, so that anyone can modify it, since I've got reasonable idea from the thread so far, but it will need refining since it's just ideas currently. It's easy to copy the PowerPoint slide into the same deck, and modify it to express other possible implementations by anyone.

Otherwise I can use Visio although I don't like it as much, and I'm much quicker with powerpoint. Anyway it's easy to copy-paste from Powerpoint or Visio into any other application like Word etc, or generate .png graphics for open documents, and so on. Any good documentation or organising or any other contribution would be great if you don't mind helping fmilburn or Jan or anyone (and collectively we might eventually know about as much archaeology as that kid Short Round in Indiana Jones), and hope your home moving-in is going well Frank!!

I'll post my ideas so far as a hand drawn and scanned block diagram - but not until tomorrow since I have no scanner or squared paper here.

MK

Hi Shabaz,

(1) and (2) in the Snuffler capabilities would seem easy to implement on a relatively low resolution screen In the field as you suggest. For a 20x20 or even 40x40 grid a simple graphic like heatmap in MATLAB could be displayed easily enough with a uC. That would allow an operator to see fliers or anomalies as they are appear.

Thanks Shabaz and Michael,

Readers looking at this for the first time and mechanical engineers without a clue everywhere will thank you for the block diagram. PowerPoint is the universal tool of corporate drones and I know it well :-)

michaelkellett Michael, Did I say laptop? Nope, Nada. what I said was a display and a keyboard of some sort. The display could be a 4x20 I²C LED Thing. And the keyboard could just be a pad or a full USB/ps2 keyboard (your choice!) there are three so pick one. LOL.

~~Cris.

Good news, I searched around for a way to get USB UART with Android, and had some luck! I found some source code for MCP2221, and got it to eventually compile:

That's just the simulator, I need to test on my phone (I couldn't find my USB OTG cable, but I'll search for it later today, and then try it with a couple of baud rates to see what's supported!

Hi a full graphics display wouldn’t be entirely necessary. It was done a few years back on a unit by T R SYSTEMS. They seem to have disappeared though. It was a box of electronics mounted on the side of the frame and an android tablet mounted facing the operator. The connection was remote and I guess Bluetooth. It’s complicated when surveying to work out exactly where you are on a grid, what with 20 rows to survey and 400 readings to take. Seeing numbers relating to your position is good, but it can still be confusing. We also have the added complication of obstructions, such as trees where we can take a reading. A dummy reading is taken in these instances. I’ve posted up my build of the original 2003 resistivity logger and there is also the GEOSCAN RM85 offering, both I feel overcomplicated in the number of buttons and very small displays. Equally the RM FROBISHER unit has a minimalist design, but a nightmare menu system behind it.