Damian Kula

Seismometers are kind of a niche equipment and not many people write about them. In fact, it's almost impossible to find any sort of a review of this kind of equipment online. That's a pity because a lot of knowledge is kept in darkness, passed from engineer to engineer, often lost in the process. I was fortunate enough that I was working with amazing technical team from RENASS observatory in Strasbourg who helped me a lot with debugging and solving both hardware and software problems. Unfortunately, it might not always be the case thus I decided to write down a few observations and experiences with hardware I was using in my seismic network, namely Nanometrics Taurus.

Nanometrics Taurus is quite old device, yet still quite common. Taurus was developed and released to public somewhere in early 2000s. The first mention of Taurus in their website was in January 2004 according to WebArchive's snapshot of their website. _[2] They don't list it on their website anymore and don't share historical information about it so it's hard to say when they stopped producing it. I think, units I was using were purchased from producer around 2012.

From my own experience, this device can be a bit iffy sometimes but in general view it's quite reliable. The biggest pain in prolonged usage of Taurus, without the GSM connectivity, are the storage cards. It happened to one or two units I am using that one month I was leaving the Taurus all green but next time I came it was red because the Archive card was not properly recognized/initialized. It was not a gigantic problem for me as I was checking out the stations almost every month but if your network is located in very remote places it might be a big issue. I would recommend to check after an hour of two from inserting the card and starting the unit if the data are properly written to the archive. Sometimes it would be even more optimal to take a look at the station a day or two after taking out the card.

In case if data were not written to the archive you might recover at least some of the lost data from the 'Store'. 'Store' is the internal binary data storage that is being written to a store card. Periodically, data from Store are being exported to miniseed files (or other configured format) and written to a second card, Archive card. In the Store data are by default stored in the way that if the card is full, the oldest data is overwritten. If the archive card gets full, it's stops writing to it. SO technically, the maximum time between two data pickups is the time it takes to write the whole Archive and Store card. However, I would not recommend doing that because retrieval from the Store by hand is quite annoying, especially if you have big network.

In order to retrieve data from the Store you have to fetch from the internal memory the store files. If you have a direct access to the digitizer you can just collect a store files from the digitizer. After getting the data to your workstation, get Apollo Software from Nanometrics and export data to some standard format.

Since I installed GSM connection in my network, working with Tauruses became just a pleasure - there were no technical problems at all. It appears that if you are not touching CF cards or you don't need to wait for it for 15 minutes to boot up when it's 3 °C and it's raining, it's pleasant device to use. I think in general, the biggest frustration I had with it was the general slowness of reaction and all the processes that are required to be performed prior taking out the card to pickup data.

Also, once it happened that two of the devices I am using stopped writing all the data to the archive. It appeared to be quite random process, on daily basis I was getting instead of 72 files a day, around 50-60. Usually files that were missing were coming from the same channel, but it was not always the case. On one day some hours from channel E were missing, on other day from channel N. Unfortunately, together with the Nanometrics support team we were not able to fully debug that problem. The thing that helped for this issue was formatting the store card and recreating store files. After performing that procedure, the problem disappeared and did not come back since then. Before formatting the store, I copied all the store files and exported data by hand using Apollo software. It turned out that the export from store contained all the missing signals.

One more thing that happened very recently - Taurus somehow killed the EXT3 filesystem on CF card. It happened almost simultaneously on two stations what was weird. The card was not recognized properly, formatting through the web interface of Taurus was not helping. The solution was to take the card of the device, fix the filesystem with fsck tool, recover the data and reformat it as EXT3. After that it resumed to work as usual and I was able to recover the data properly.

Anyway, here are a few notes, opinions, tips and tricks about usage of Taurus.

1. Have CF cards either Sandisk Extreme Pro or Belkin. Official recommendation set the maximum size at 8GB but I am running 16GB on my Archive card and it's fine. Quite frankly, I did not test any card with higher capacity. If you are reading it in 2020 or later and you want to use Tauruses for longer, I would definitely recommend to start looking for a lot of cards ASAP. I was looking for some in 2018 and prices of compatible ones were incredibly high and also the stocks were pretty low everywhere.
2. Archive card has to be formatted in FAT32, Store card has to be formatted in Ext3.
3. If you are having problems with card not being recognized by Taurus, turn it off, take the card out and put it back again.
4. If it didn't help, reformat it in the computer and/or reformat it with Taurus.
5. If Taurus stopped recognizing card that was recording data to, it properly has broken filesystem. Recover the card, fix the filesystem, recover the data.
6. Ground the device. Sometimes not grounding your device might end up with getting a square signal. If it happens, turn it off, ground it, give it 15 mins and power it back on again.
7. Give it time. I know it is very slow but often it will be just better for you and your data to wait for that confirmation of fully green status.
8. Don't cover GSM antenna with anything. Have it completely exposed to the sky.
9. If your antenna cable will become a snack to some rodents, don't worry, it's totally possible to solder it back together.
10. If your Taurus is stuck in a bootloop and the UI doesn't have enough time to come up online, one of the possible reasons might be problem with the Store card. Check if it is present and if it works. (Thanks anonymous reader for that piece of knowledge!)

Do you have some of your own observations and experiences with Taurus? Did you have some problems that you managed to solve? Do you have some idea how to make working with Taurus easier? Leave the comment!

Disclaimer! I'm not affiliated at all with Nanometrics neither I have extremely extensive experience with the devices. My observations are coming from almost 3 years of working with a network of few Tauruses among other digitizers.

[1]	https://github.com/iris-edu/dataselect

[2]	https://web.archive.org/web/20040926042151/http://nanometrics.ca/

[3]	https://github.com/iris-edu/dataselect/blob/master/doc/dataselect.md#archive-format