I'm a seismic geophysicist and would like to attach a geophone - which is basically a transducer - to any type of RP. The types and costs of geophones are both variable and extensive (in some cases). The main idea to note is this: a geophone (or array of geophones, perhaps) usually records ground displacement in 1-, 2-, or 3-D and sends the signal off as either an analogue or digital output. I want to record that signal in real-time via a RP and (eventually) develop a pipeline to send that data to a cloud database.

How might I do this?

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    Hi @Nathan Benton, Welcome and nice to meet you. Your question is interesting. So I wikied to know more: Geophone Construction - Wikipedia (1) Geophones have historically been passive analog devices and typically comprise a spring-mounted wire coil moving within the field of a case-mounted permanent magnet to generate an electrical signal. (2) Recent designs have been based on microelectromechanical systems (MEMS) technology which generates an electrical response to ground motion through an active feedback circuit to maintain the position of a small piece of silicon. / to continue, ... – tlfong01 Nov 20 '19 at 14:15
  • (3) The response of a coil/magnet geophone is proportional to ground velocity, while MEMS devices usually respond proportional to acceleration. MEMS have a much higher noise level (50 dB velocity higher) than geophones and can only be used in strong motion or active seismic applications. / to continue, ... – tlfong01 Nov 20 '19 at 14:16
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    And in case what the Wikipedia says is true, ie mechanical coil spring sensors have low noise level compared to piezo MEMS gyro/accelero, we can perhaps use a hybrid approach, combining the cheapie but miniature 801 type sensor, augmented with more noisy MEMS but digitally filtered. imgur.com/gallery/leMnH1c. – tlfong01 Nov 20 '19 at 14:58
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    Hi @Nathan Benton, Ah yes, you are right in pointing out that your signal frequency is VERY LOW 5~20 second period (of order 0.01 Hz). I happened to once played with low frequency brain wave (Alpha Beta etc), of range 1 to 20 Hz. Of course you frequency range is one order smaller. My brainstorming idea is to use "long mechanical coil springs or flexible blades" perhaps 12' long, with MEMS gyro/accelero attached at the end of the long spring/blade. A similar method is to use sort of long arm pendulums, also with MEMS gyro/acceleros at the end. Bed time. See you later. Cheers. – tlfong01 Nov 20 '19 at 15:26
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    There's stuff from 2012 onwards on seismography at raspberrypi.org/forums/viewtopic.php?f=37&t=3731 – Dougie Nov 21 '19 at 8:09

After reviewing the material provided here and conducting more research, I've decided that - as a benchmark for future advances in availability and especially price - this option is a great place to start resolving the issue/question posed here.

  • That product looks promising. One thing to note about the RasPi is that it doesn't have an onboard ADC, so any analog transducer will need some peripheral circuitry. – BobT Dec 3 '19 at 14:34

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