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Changes for page ANU Seismic Data Loggers

Last modified by robert on 2025/06/30 19:28
From version 50.2
edited by robert
on 2025/06/30 19:26
Change comment: There is no comment for this version
To version 49.1
edited by robert
on 2025/06/27 16:42
Change comment: There is no comment for this version

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165 165  
166 166  = Instrument Response =
167 167  
168 -Both the TerraSAWR and LPR-200 use the same ADS1281 analog-to-digital converter chip and are designed to have identical instrument response. The ADC (analog to digital) chip in both loggers originally samples at 1024000 Hz and downsamples towards the output data rate via a 5th order SINC filter, then another four FIR filters. If the output is below 250 Hz, a final "pure" /5 decimation is done without any sort of FIR filter.
168 +Both the TerraSAWR and LPR-200 use the same ADS1281 analog-to-digital converter chip and are designed to have identical instrument response. The ADC (analog to digital) chip in both loggers originally samples at 1024000 Hz and downsamples towards the output data rate via various stages. First via a 5th order SINC filter, then another 32x via 3-4 2x or 4x FIR filters. If the output is below 250 Hz, a final "pure" /5 decimation is done without any sort of FIR filter.
169 169  
170 170  {{info}}
171 -The Stage 3 SINC coefficients (600+) during the initial 1024k > 16k decimation were left off as they slowed down the process x10 and contribute very little (< 0.3 db, < 0.31 ms) to the end result
171 +All SINC and FIR filters are performed internally within the logger and all phase delays are accounted for. Thus, the FIR coefficients and delays are not needed/given in the response information.
172 172  {{/info}}
173 173  
174 174  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. This gain manifests itself in stage 2 in the response information.
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175 175  
176 176  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') ).
177 177  
178 -[[Huddle test comparing a Trillium Compact 120 + TerraSAWR vs a Trillium Compact 120 + Nanometrics Centaur (M8.AUANU)>>image:TC120_ANU_vs_CENTAUR.png||data-xwiki-image-style-alignment="center"]]
179 179  
180 180  = ANU TerraSAWR (Gen 3, FW 3.5a, 2017- current) =
181 181  
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213 213  
214 214  
215 215  
216 -
217 -
218 218  (% class="box" %)
219 219  (((
220 220  = TerraSAWR Specs =
TC120_ANU_vs_CENTAUR.png
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1 -XWiki.robert
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