Raspi-powered seismometer/seismograph

The python based scripts (called miniseis)were written by Jon Gilbert last year as part of his coursework at Edinburgh University. They take data from an SEP digitiser (which just produces a stream of 16 bit numbers 20 times per second onto a serial port). The code was originally written to work with the SHEEVA plug computer (an embedded linux system). The serial data comes into the SHEEVA through a USB-serial convertor. I see no reason why this should not port easily to the RasPi ( do not know whether we would need to use a USB-serial convertor or if the RAspi could read serial data directly on GPIO pins.)

The raw data is stored locally in both raw binary format (as read by Amaseis software) and also as a compressed format called miniseed (as used by seismologists all over the world). The code also broadcasts data live over a TCP connection using the same server-client protocols that AMaseis uses. It can also send data in packets to a remote web server using HTTP push. The software makes use of the Obspy python package for writing miniseed and some other functions

http://www.mutzi.co.uk/docs.tar
http://www.mutzi.co.uk/miniseis.tar
http://obspy.org

also see http://alomax.free.fr/seisgram/SeisGram2K.html for platform independant (java) seismic analysis code which reads seismic data in miniseed format

All code is open source

please feel free to email me directly if you have any queries or just to let me know how you are getting on (pdenton@bgs.ac.uk)

you might also be interested in Graeme Keon's work on using soundcards to record seismic signals
http://motivationtolearn.org/wordpress/ ... #more-1100. He uses a uses a 555 chip to modulate an audio frequency carrier with low frequency seismic signals and then record them on a cheap soundcard.

All good and gratefully received.

I already have the RPi serial port sorted out but I really want to use the I2C interface for capture if possible to simplify the process as much as possible. One option is to use the RPi with I2C to capture, filter and store the data and then the serial interface to emulate the SEP digitiser and feed it to an Amaseis. I will also be able to create data in miniseed format for compatibility with other systems when I reach the sharing stage.

Some of the code looks like it could be real time-saver. All of my code will also be available as open source and I will submit any changes/derivatives to the source groups as well.

The seismometer hardware is now done and I am just sorting out the low volume airtight lid before starting sensor tests. The electronics will be ready soon afterwards and then the RPi fun starts

I will contact you directly about items not relevant to this list.

Progress on this topic at all ?

Oh yes; I'm still tweaking the mechanics and the electronics to try and get a stable platform. I think I'm about there so the RPi interface is now on the bench.

I have a Wifi AP in range of where the seismometer will be permanently sited and a large solar cell designed for charging car batteries which should keep the whole thing running 365/24/7.

I will post an update once I have the RPi side up and running.

Good to know. I would be interested in your mechanical side.

It's a version of a fairly standard design called a Shackleford-Gundersen Seismometer. This is a 1975 design but I have updated the electronics and done all of the later improvements. A lot of folks build what is called a "swinging gate" design attributed to Lehman and it works well too but the SG unit has a smaller footprint and I just like the design better.
Once things are starting to "join up" convincingly I will post more along with some photos and, of course, the source code.

David

Hi Folks:
I hope you have a good experience putting together an earthquake seismometer.
This link,
http://www.jsasoc.com/diamagnetic_suspe ... smomet.htm
describes a VERY SIMPLE novel seismometer, using a pure graphite rod suspended
in a strong magnetic field. It responds to displacement, not velocity.
There are several design issues that need to be solved to make this work properly.
I tinkered with this but lost interest. I hope someone else takes up the project.

BTW I don't think you need lots of dynamic range in your ADC. Just look at (analog) earthquake records from years ago. They managed just fine with line widths of about 1 mm and chart widths of
about 300 mm, which is equivalent to about 8 bit resolution.
In modern times there are lots of interesting cheap ways to do the ADC.

ChucktheTinkerer