Gamma spectacular, theremino adapters, non-sound card based, etc...
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Steven Sesselmann
Posts: 677
Joined: 27 Apr 2015, 11:40
Location: Sydney


Post by Steven Sesselmann » 11 Nov 2019, 11:54

I made this device for a client who wants to conduct areal gamma surveys by drone.
Gamma Recorder front
GSGR(3).jpg (29.21 KiB) Viewed 181 times
It's essentially just a Raspberry-Pi-4 with a Python script that records a .wav sound file, but as these things go, the basic idea is simple, but final execution always ends up taking more time than expected (at least for me). I had the basic program working pretty well until I decided it would be more practical to write the file to a removable USB drive, that's when I discovered that simply plugging a USB stick into an RPI doesn't work, 10 hours later after reading all the posts by others who had the same problem, I finally found the work around.
Gamma Recorder back
GSGR(4).jpg (36.52 KiB) Viewed 181 times
Anyway here is how it operates..

Insert the small black Lexar USB drive in any of the USB ports.
The gamma-recorder is programmed to only work with one specific USB drive, using it with other USB drives will require a change to the code.

Connect the GS-USB-PRO to any of the other USB ports.

Connect a USB power supply capable of at least 2.5 mA. and wait !!
The RPI will immediately start the booting up process (there is no on/off switch)
During the boot process, the RPI will look for and mount the USB drive
The python script will automatically execute and indicate ready when the yellow LED light comes on.

Start recording by pressing the red button once.
The yellow led will switch off
The red led switches on indicating that the system is recording.
Survey mission can begin

Stop recording by pressing the red button once and wait (be patient).
Both LED indicators will switch off while the computer is writing to disk.


You will see a blue led flashing in the USB drive twice
At this stage the recording has been saved on the drive as YYMMDD-HH-MM-SS.wav
Go to step 5 only when all activity has stopped and the yellow LED comes back on

< DECISION > Back to step 3 to start another recording or Proceed to step #5 to exit

Press and hold the red button for 5 seconds to unmount the USB and exit program.
The USB drive can now be safely removed and the files transferred to a PC for post analysis with Pulse Recorder and Analysis (PRA).

After the survey mission you simply transfer the audio file to a PC and open it in PRA. The objective with this kind of survey is to produce a time stamped 3D map which can then be mapped using GPS positions.

The exact recording end time is in the file name, so in PRA the bin size for count rate vs time can be set to say 60 seconds, so you can correlate counts with position.

I took the equipment for a test in my car and it performed as intended, although the 30 minute drive didn't reveal anything too interesting.

If anyone wants to try this route, just send me a PM, I am happy to share the python script and save you hours figuring out how to write to a USB drive.

The whole gamma recorder kit with 3" detector
Steven Sesselmann | Sydney | Australia | | | |

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