Data Storage And Formats - Gecko Compact Product User Manual

Data Storage and Formats

The Gecko stores continuous data to the SD card in a logical file hierarchy to make it easy
to find the data you're looking for, but it also stores some additional files that you may find
useful. The SD card is formatted in standard FAT32 file system and can be read by most
computers with an SD card slot or using a USB SD card reader.
The sample rate affects the size of the data files stored, so we will briefly discuss how much
data you can expect to record given a particular sample rate. The Gecko is recording data to
the SD card continuously in MiniSEED format using Steim-1 compression. Data is stored on
the SD card in one-minute long files in a Year > Month > Day > Hour folder hierarchy to
make browsing data on your computer as easy as possible.
Your Gecko will probably be recording low levels of signal from your sensor most of the
time, so the data files are usually quite small. The occasional earthquake or noise signal will
increase the size of the data files in the short term, but for estimation purposes we will look
at what volume of data is generated at typical background signal levels.
Recording 3-channels at 100sps in an urban environment generates about 2GB per month.
Increasing the sample rate to 250sps generates about 5GB per month, and running at
4000sps creates about 70GB per month, so the sample-rate to data-volume relationship is
reasonably linear. Low noise environments (such as underground vaults or remote stations)
will generate smaller amounts of data due to the MiniSEED format data optimisation.
At a quiet station, recording
at 100sps, the standard 32GB
SD card will typically store
about 20 months of
continuous triaxial data in
the ring buffer.
You can view your data by inserting your SD card into your computer and starting up
Waves. Simply drag a single file, an hour folder, or a day folder (Waves can display up to
24 hours data in a single window) onto the empty Waves viewer window to view your data.
Waves will read the ".ss" file from your data folder to auto-fill the station information. Keep
your files in their respective folders or risk losing this meta-data link, or save the file in a
meta-rich format like PC-SUDS, or as a MiniSEED zip file (where the waveform file and .ss
files are zipped together into a folder that can be read directly by Waves without
decompression).
Download Waves for free from http://www.src.com.au/downloads/waves/
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