Power Considerations

Both the LPR-200 (or "Low Power Recorder" 200) and TerraSAWR are designed to use as little power as possible, and more or less use the same amount of power.

At 100 Hz and with a GPS cable connected these loggers draw about 220 mW of power once the screen is off. Adding a sensor (e.g. a Trillium Compact 120) increases this to approximately 400 mW, or 0.4 volt-amps. So, in theory 7 Ah battery should last about 10 days without a solar panel, but in practice it seems to be a bit closer to 8 which may be due to variability in power drain while in getting GPS locks.

For very sunny environments (latitudes < 30) a 20V 10 Watt solar panel should have no issue keeping these loggers alive over the summer months, and assuming unobstructed skies should also be fine over winter. However there is no harm in using 20 or even a 40 Watt panel, especially for high latitudes, coastal regions, or areas without a full sky view. In theory up to a 60 Watt solar panel is fine, but we don't recommend anything over 40 Watts and that amount of power is already overkill.

Data Card Formatting and Information

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 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.

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" for the LPRs, or "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.

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

XXX195G0100010034864      2 

corresponding to

                 site XXX19,
                 network 5G,
                 sample rate 0100, (i.e. 100 Hz)
                 "gps interval" 01 (once per hour-- don't change),
                 start mode (always 0),
                 stop mode (always 0),
                 seismometer type (3 = broadband (+/- 20V), 2 = Guralp (+/- 10V), 1 = shortperiod (+/- 5V),
                 and seismometer serial number (4864).

The format for TSAWR loggers is shorter:

SITE15G02500039999      2 

corresponding to site SITE1,  

                 network 5G
                 sample rate 0250, (i.e. 250 Hz)
                 start mode (always 0),
                 stop mode (always 0),
                 seismometer type (3 = broadband (+/- 20V), 2 = Guralp (+/- 10V), 1 = shortperiod (+/- 5V),
                 and seismometer serial number (9999).

The formatting process using the logger:

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

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

  64Gb card: 245 days @ 250hz or 610 days @ 100hz
  32Gb card: 122 days @ 250hz or 305 days @ 100hz

Default Settings

As of 2025, the default settings for both LPR (v. 2.7) and TSWAR (v 3.6a) loggers are below. If you're using a broadband instrument, you are essentially good to go without having to program the cards.

• XX.ANUSR network and station name
• 100 Hz Sample Rate
• 40V pp (or +/- 20 V) gain / Trillium Compact seismometer version
• Record on Restart enabled

Note that if a user sets the gain incorrectly, this can be fixed later (assuming nothing clipped) by multiplying or dividing by factors of 2. The gain setting can be looked up from the logfile, else you may have to guess from a PSD or other method.

Logger Menus Overview (and setup)

The same menus are used in both the TSAWR and LPR-200 loggers.

System Information

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.

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

• Check all Initialisation Parameters are marked as successful.
• Check that solar voltage is above 10 V, otherwise the station will not last long.

Live Seismometer Data

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.

• Check that all 3 channels are present and are producing a signal.
• Stomp on the ground near where the sensor is installed to check that a signal is being picked up by all 3 channels.
• 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.

• 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.

System Configuration

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

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).

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

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

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

• Trillium Compact (same for 20 and 120)
• 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

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.

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

STA/LTA Configuration

The Short Term Average and Long Term Average Configuration screen.. this is a relic for when people weren't recording continuously. Not advised!

LogFile Conversion Script

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.

Instrument Response

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, 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).

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.

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).

Instrument response can be downloaded from IRIS Nominal Response Library if need be, or directly from us , or by downloading the response of an equivalent sensor at AusPass (e.g. get_stations(level='response') ).

The response info from IRIS-NRL is the "full" version which (in theory!) perfectly describes the data logger's bias on the data. However this is in many way overkill and at the cost of 1) increased metadata size and, more importantly, 2) increased CPU demand in the response removal process. Testing has shown that for signals below 100 Hz, the "full" response offers little to no benefit and can increase the time it takes to remove the response for a 1 hour window of 100Hz data by a factor of x20 or more. For earthquake arrival data this is often negligible, but for data intensive tasks like ambient noise cross-correlations this can be a severe hindrance. Thus we have created a parallel version of this response which removes the SINC and FIR filters completely. These are labelled "fast" in our local response archive and essentially truncate response stages 3 onwards into a "fake" decimation step from 1024000 Hz to the desired output samplerate with no filtering whatsoever.

In the below we show both responses applied to a test signal with a frequency range of 1000 seconds to 100 Hz. The maximum discrepancy in signal is less than 0.01% (1.0001) which is far below what you should expect from the mechanical inconsistencies intrinsic to the sensor itself. Thus, we strongly advise users employ the "fast" version of this response information and it is what we use for our networks by default. If you are recording at 1000 Hz, or care deeply about signals above 100 Hz (so recorded at 250 or 1000 Hz), please use the full response. Any questions, please ask!

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

Not sure there's much left to say

ANU LPR-200 (Gen 2, FW 2.6a/2.7a, 2013 - current)

Ditto the mighty LPR!

ANU "ANUSR" (Gen 1, 2003? - 2012)

This logger has been retired for a long time and has a different instrument response. It used modular component boards and was powered via an acrylic case of 6 x 6V lantern batteries. There is a somewhat complete one above the CAT lab door if anyone is so inclined to have a look.

References

• PDF Manual