Changes for page ANU Seismic Data Loggers
Last modified by robert on 2025/08/08 16:09
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... ... @@ -170,42 +170,12 @@ 170 170 171 171 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 (for better or worse!). 172 172 173 -In the logger's menu, 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. 174 - 175 175 //(The 600+ Stage 3 SINC coefficients during the initial 1024k > 16k decimation were left off as they slowed down the process x10 and contribute at most 0.3 db amplitude and 0.31 ms phase delay discrepancies, and primarily only to frequencies near the nyquist. If for some reason you want to add this phase manually we can share the parameters with you.)// 176 176 177 -You might notice that the response information may come in two versions. The response from our website (see link below) includes the 2nd "sensor gain" stage for clarity. e.g. here is a Trillium Compact 120 & ANU Logger response 178 - 179 -##Channel Response 180 - From M/S (Velocity) to COUNTS () 181 - Overall Sensitivity: 3.95452e+08 defined at 1.000 Hz 182 - 8 stages: 183 - Stage 1: PolesZerosResponseStage from M/S to V, gain: 754.3 184 - Stage 2: ResponseStage from V to V, gain: 0.25 185 - Stage 3: CoefficientsTypeResponseStage from V to COUNTS, gain: 2.09715e+06 186 - Stage 4: FIRResponseStage from COUNTS to COUNTS, gain: 1 187 - Stage 5: FIRResponseStage from COUNTS to COUNTS, gain: 1 188 - Stage 6: FIRResponseStage from COUNTS to COUNTS, gain: 0.99998 189 - Stage 7: FIRResponseStage from COUNTS to COUNTS, gain: 1 190 - Stage 8: FIRResponseStage from COUNTS to COUNTS, gain: 1## 191 - 192 - 193 -However, if retrieving from AusPass or IRIS, the 2nd "sensor gain" stage is combined with the logger gain. This has no affect, but will be one stage short: 194 - 195 -##Channel Response 196 - From M/S (Velocity) to COUNTS () 197 - Overall Sensitivity: 3.9546e+08 defined at 1.000 Hz 198 - 6 stages: 199 - Stage 1: PolesZerosResponseStage from M/S to V, gain: 754.3 200 - Stage 2: CoefficientsTypeResponseStage from V to COUNTS, gain: 524288 201 - Stage 3: FIRResponseStage from COUNTS to COUNTS, gain: 1 202 - Stage 4: FIRResponseStage from COUNTS to COUNTS, gain: 1 203 - Stage 5: FIRResponseStage from COUNTS to COUNTS, gain: 0.99998 204 - Stage 6: FIRResponseStage from COUNTS to COUNTS, gain: 1## 205 - 206 - 207 207 For the most part, the data logger response essentially flat when the samplerate output is set to 100 Hz or less and for seismological purposes is likely to be impossible to detect below 20 Hz regardless. 208 208 177 +In the logger's menu, 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. 178 + 209 209 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') ). 210 210 211 211 ... ... @@ -265,7 +265,6 @@ 265 265 266 266 267 267 268 - 269 269 (% class="box" %) 270 270 ((( 271 271 = TerraSAWR Specs = ... ... @@ -319,6 +319,5 @@ 319 319 320 320 321 321 322 - 323 323 324 324 )))