ANU Seismic Data Loggers

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ANU has designed and built three generations of seismic data recorders, two of which (the small yellow TerraSAWR and the larger beige LPR-200) are still in use today. Despite their contrasting appearance, they both use the same software, data cards, and have the same instrument response.

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= Data Card Formatting and Information =

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Both the TerraSAWR and LPR-200 require SD Cards to be formatted in FAT32 filesystem. For 64Gb cards it can be difficult to format in FAT32, but [[software >>http://auspass.edu.au/field/fat32cardformatter.exe]]is available. ANU recommend SanDisk Extreme 150 mb/s cards in either 32 or 64Gb size. We strongly discourage using cards larger than 64Gb, and in general smaller cards are less likely to fail. We have also found that "adapter" cards (e.g. SD to microSD) are prone to having write issues and **strongly** advise against them.

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The loggers can be "pre-programmed" with information (e.g. site name, sampling rate, etc) or they can be programmed in the field using the buttons on the logger. To pre-program the cards you simply edit a text file (named "[[ANUSRSetup.txt>>http://auspass.edu.au/field/ANUSRSetup.txt]]" for the LPRs, or "[[tSAWRSetup.txt>>http://auspass.edu.au/field/tSAWRSetup.txt]]" for the TerraSAWRs) and place it in the root directory on the SDCard. When the logger boots up, it will parse and load this information.

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=== The format for ANUSRSetup.txt / LPR200s will be a single line of text that looks like this: ===

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{{{XXX195G0100010034864 2 }}}

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corresponding to site XXX19,

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network 5G,

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sample rate 0100, (i.e. 100 Hz)

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"gps interval" 01 (once per hour~-~- don't change),

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start mode (always 0),

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stop mode (always 0),

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seismometer type (3 = broadband (+/- 20V), 2 = Guralp (+/- 10V), 1 = shortperiod (+/- 5V),

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and seismometer serial number (4864).

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NOTE: the 2 at the very end is for "RECORD ON RESTART". The record on restart option ensures that if the logger dies and is powered back up whilst in the field (due to battery charging cycles or other causes) that the recording will resume. (# of blank spaces before this doesn't matter)

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=== The format for TSAWR loggers is shorter: ===

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**NOTE: The format is shorter as they don't have an option to set the "GPS sync". The GPS sync number should be omitted otherwise the formatting will not work!**

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SITE15G02500039999 2

corresponding to site SITE1,

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network 5G

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sample rate 0250, (i.e. 250 Hz)

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start mode (always 0),

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stop mode (always 0),

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seismometer type (3 = broadband (+/- 20V), 2 = Guralp (+/- 10V), 1 = shortperiod (+/- 5V),

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and seismometer serial number (9999).

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=== The formatting process using the logger: ===

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The process for formatting an SD card within the logger is straightforward. Navigate to the "SD INFORMATION" screen and press ERASE SD CARD. This process may take up to a minute. This will result in erasing all files from the card. Upon starting recording, a new 'seed' will be written containing all the information that the logger has been set with FINISH THIS SECTION

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Here is a general guideline for how much data you can expect to fit on a card:

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{{{ 64Gb card: 245 days @ 250hz or 610 days @ 100hz

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32Gb card: 122 days @ 250hz or 305 days @ 100hz

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= Logger Menus Overview (and setup) =

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The same menus are used in both types of loggers.

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== System Information ==

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This menu provides an overview of the status of the station. Under 'Initialisation Parameters', the status of systems that are initialised upon powering on the logger can be checked.

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This menu also displays the firmware version, battery, external, and solar voltages, and the temperature of the system.

==== Upon setup ====

- Check all Initialisation Parameters are marked as successful.

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- Check that solar voltage is above 10 V, otherwise the station will not last long.

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== Live Seismometer Data ==

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This screen displays real time seismometer data for all 3 axes of the seismometer. Initially, a plot of raw data from all 3 channels is shown. By pressing enter, a high pass filter can be applied showing a more useful plot of all channels. The up and down arrows can be used to change between a view of all channels, individual channels, and all channels on different X axes.

==== Upon setup ====

- Check that all 3 channels are present and are producing a signal.

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- Stomp on the ground near where the sensor is installed to check that a signal is being picked up by all 3 channels.

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- Common representations of poor signals include channels sloping smoothly from high values to zero, or sharp corners in the plots.

== GPS Data ==

This menu displays the status of the stations' GPS connection. The screen lists; UTC time, UTC date, latitude, longitude, altitude, number of satellite connections, and SNR.

==== Upon setup ====

- Check that the station is connected to satellites

== SD Information ==

The menu lists if the SD card has been initialised, as well as the capacity and space free on the memory card. See "Data card formatting" (above) to see how to format and initialise the inserted SD card.

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== System Configuration ==

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This menu is used to set the stations identifiers and parameters.

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First, the sampling rate can be chosen from a set of options (1 Hz, 10 Hz, 25 Hz, 40 Hz, 50 Hz, 100 Hz, 250 Hz, 1000 Hz).

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Next, the station identifier (up to 5 characters) and the network code (2 characters) can be set.

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Record start and stop mode should be left to 'On Request' mode.

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The seismometer model and serial number (up to 10 characters) can be set. Seismometer model options include:

- Trillium Compact

- CMG - 3ESP

- Guralp 40T

- LE-3D Lite

- Mark L4C

- Mark L4

Additionally, the following settings can be used in place of the seismometer model types: +/- 20V, +/- 10V, +/- 5V

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The record on restart option ensures that if the logger dies and is powered back up whilst in the field (due to battery charging cycles or other causes) that the recording will resume.

==== Upon setup ====

- Set the sampling rate, station identifier, and network code. Set the appropriate seismometer type. Most importantly, ensure the record on restart setting is checked.

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NOTE: Ensure the 'RECORD ON RESTART' option is marked with a cross.

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== STA/LTA Configuration ==

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= LogFile Conversion Script =

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Both the TSAWR and LPR-200 write logging information as a binary "dat" file which includes GPS time syncs, temperatures, battery power, and position. To convert them into ASCII you can read, use [[THIS PYTHON SCRIPT>>http://auspass.edu.au/field/anusr_log.py]].

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= Instrument Response =

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Both the TerraSAWR and LPR-200 use the same ADS1281 analog-to-digital converter chip and are designed to have identical instrument response. Depending on the output sample rate (e.g. 100 Hz, 250 Hz, 500 Hz, 1000 Hz) amplitude response is consistently flat up to ~~100 Hz but phase response can vary above 1 Hz at 100 Hz (or 10 Hz at 250 Hz).

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The user can choose to apply a 2nd stage "sensor gain" by selecting an instrument type in the setup menu. This effectively selects a 10 Vpp (e.g. short period sensors), 20 Vpp, 40 Vpp (most broadband sensors) regime to match the sensor's sensitivity. This has the effect of doubling amplitude from 10v to 20v, or quadrupling from 10v to 40v. If you have set your sensor correctly (and the signal isn't clipped!) you can "correct" this by simply multiplying your data by 0.5 etc.

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Another important thing to note is that the group delay associated with late stage FIR filters is **automatically applied in the logger**, hence there is no need to apply this in the response. These tend to max out at 0.124 seconds for most output sampling rates (0.062 s for 100 Hz).

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Instrument response can be downloaded from IRIS-NRL (v2) if need be, or by downloading the response of an equivalent sensor at AusPass (e.g. get_stations(level='response') )

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= ANU TerraSAWR (Gen 3, FW 3.5a, 2017?- current) =

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