Changes for page ANU Seismic Data Loggers

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• Page properties (1 modified, 0 added, 0 removed)
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  • full_vs_fast.png

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30	30	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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32		-=== The format for ANUSRSetup.txt / LPR200s will be a single line of text that looks like this: ===
	32	+== The format for ANUSRSetup.txt / LPR200s will be a single line of text that looks like this: ==
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34	34	{{{XXX195G0100010034864 2 }}}
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49	49	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)
50	50	)))
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52		-=== The format for TSAWR loggers is shorter: ===
	52	+== The format for TSAWR loggers is shorter: ==
53	53
54	54	(% class="box errormessage" %)
55	55	(((
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68	68	and seismometer serial number (9999).
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71		-=== The formatting process using the logger: ===
	71	+== The formatting process using the logger: ==
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73	73	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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172	172	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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174		-Instrument response can be downloaded from IRIS-NRL (v2) **TODO ADD LINK** if need be, or by downloading the response of an equivalent sensor at AusPass (e.g. get_stations(level='response') )
	174	+Instrument response can be downloaded from IRIS [[Nominal Response Library>>https://ds.iris.edu/ds/nrl/]] if need be, or [[directly from us>>http://auspass.edu.au/data/logger_response]] , or by downloading the response of an equivalent sensor at AusPass (e.g. get_stations(level='response') ).
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	176	+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>>http://auspass.edu.au/data/logger_response]] and essentially truncate response stages 3 onwards into a "fake" decimation step from 1024000 Hz to the desired output samplerate with no filtering whatsoever.
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	178	+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!
	179	+
	180	+[[Testing the "full" and "fast" versions of the ANU data logger response on synthetic 250 Hz data from 1000 seconds to 100 hertz. For all intents and purposes, they are identical.>>image:full_vs_fast.png||data-xwiki-image-style-alignment="center"]]
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	182	+
177	177	= ANU TerraSAWR (Gen 3, FW 3.5a, 2017- current) =
178	178
179	179	Not sure there's much left to say
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	217	+
211	211	(% class="box" %)
212	212	(((
213	213	= TerraSAWR Specs =

full_vs_fast.png

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	1	+XWiki.robert

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	1	+40.6 KB

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