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Last modified by robert on 2024/05/17 16:52
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1 -Distributed Acoustic Sensing
1 +integrated Distributed Acoustic Sensing (iDAS)
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1 +XWiki.sima
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1 += **What is iDAS?** =
2 +
3 +**iDAS** stands for **Integrated Distributed Acoustic Sensing**. This advanced system utilizes the principle of Rayleigh backscattering in optical fibers to measure strain rates along the fiber's length. It's a cutting-edge technology predominantly used in fields like geophysics, where it's crucial for monitoring seismic activities, as well as in industrial applications like pipeline monitoring and security systems.
4 +
5 +=== **Safety first!** ===
6 +
7 +=== ===
8 +
9 +(% class="box warningmessage" %)
10 +The iDAS uses a Class 1 laser, which is generally considered safe for most applications. However, direct exposure to the eye should be avoided to prevent any risk of eye injury.
11 +\\Cables and fibers may create tripping hazards. Ensure that the routing of cables is done in a way that minimizes the risk of accidents.
12 +
13 +----
14 +
15 +=== **System Components** ===
16 +
17 +**Interrogator Unit**
18 +
19 +* The heart of the iDAS system, this unit contains the laser source, a detector for capturing backscattered light, and electronics to process this signal. It's critical for generating and interpreting the data collected by the optical fiber.
20 +
21 +**Optical Fiber**
22 +
23 +* This component acts as a long, distributed sensor. Strain rates along this fiber are what the iDAS system measures and analyzes.
24 +
25 +**Data Acquisition Software**
26 +
27 +* This software interfaces with the interrogator unit, allowing users to configure acquisition parameters, initiate data capture, and process the collected data.
28 +
29 += =
30 +
31 += =
32 +
33 += **DAS Data Collection System** =
34 +
35 +==== **1. Interrogator Unit** ====
36 +
37 +* **Function:** The interrogator unit is the core component of a DAS system. It sends laser pulses through the optical fiber and measures the backscattered light.
38 +* **Recording Information:** It records various settings such as the optical system configurations, spatial sampling rates, and the duration of data acquisition.
39 +* **Multiple Interrogators:** More than one interrogator may be used in an experiment. Each unit should have a unique identifier and is described in its respective metadata block.
40 +
41 +==== **2. Surface Installation** ====
42 +
43 +* **Cable Arrangement:** The optical fiber cable can be a single long continuous cable or multiple cables with connectors, used across different installation environments.
44 +* **Cable Types:** Cables may vary in construction types based on the installation environment.
45 +* **Geographical Metadata:** Parameters related to geographical location are specified for easy searchability in databases.
46 +
47 +==== **3. Fiber Optic Cable** ====
48 +
49 +* **Cable Composition:** Several optical fibers may be enclosed within one cable.
50 +* **Metadata Identification:** The metadata identifies each individual fiber used in the acquisition, including its intrinsic properties.
51 +
52 +==== **4. Installation Environments** ====
53 +
54 +* **Shallow Burial:** The cable can be shallowly buried.
55 +* **In-Conduit Installation:** The cable can also be installed within a conduit.
56 +* **Water Installation:** Suitable for underwater environments.
57 +
58 +==== **5. Channels** ====
59 +
60 +* **Sensor Distribution:** Channels represent sensors distributed along the fiber array at fixed intervals.
61 +* **Physical Location Determination:** The physical locations of these channels are ascertainable through methods like tap tests and GPS tracking.
62 +* **Metadata for Channels:** Each channel or group of channels has its own metadata block, detailing specifics like location and properties.
63 +
64 +[[image:1706489800616-982.png]]
65 +
66 +
67 +
68 +[[image:1706488566274-805.png]]
69 +
70 +----
71 +
72 += **DAS Metadata Schema** =
73 +
74 +==== **1. Interrogator** ====
75 +
76 +* **Required:** Interrogator ID, manufacturer, model.
77 +* **Optional:** Serial number, firmware version.
78 +
79 +==== **2. Acquisition Parameters** ====
80 +
81 +* **Required:** Interrogator ID, acquisition ID, unit of measure, acquisition start and end time, acquisition sample rate, gauge length, number of channels, spatial sampling interval.
82 +* **Optional:** Pulse rate, pulse width.
83 +
84 +==== **3. Overview** ====
85 +
86 +* **Required:** Network code, location, start date, end date, point of contact.
87 +* **Optional:** Digital Object Identifier (DOI), purpose of data collection, funding agency.
88 +
89 +==== **4. Cable Information** ====
90 +
91 +* **Required:** Cable ID, cable bounding box.
92 +* **Optional:** Cable owner, cable installation date, cable characteristics.
93 +
94 +==== **5. Fiber Information ('Native format')** ====
95 +
96 +* **Required:** Cable ID, fiber ID, fiber geometry, fiber mode, fiber refraction index.
97 +* **Optional:** Fiber optical length, fiber start and end location, fiber one-way attenuation, fiber winding angle.
98 +
99 +==== **6. Channel Group** ====
100 +
101 +* **Required:** Interrogator ID, acquisition ID, channel group ID, cable ID, fiber ID, coordinate generation date.
102 +* **Optional:** Location method, coordinate reference frame, first/last usable channel ID, uncertainty of various coordinates (x, y, latitude, longitude, elevation, depth, strike, dip).
103 +
104 +==== **7. Channel** ====
105 +
106 +* **Required:** Channel group ID, channel ID, coordinates (x, y, latitude, longitude).
107 +* **Optional:** Elevation above sea level, depth below surface, distance along fiber, strike, dip.
108 +
109 +----
110 +
111 +=== ===
112 +
113 += **Pre-processing Steps for DAS Data (2.5 months, 90 TB)** =
114 +
115 +1. (((
116 +**Create a Deployment Log**
117 +
118 +* Document key details like photonics settings, duration of data collection, instances of hard disk failure, power outages, etc.
119 +)))
120 +1. (((
121 +**Generate Geographic Coordinates**
122 +
123 +* Assign latitude and longitude coordinates to each DAS channel for spatial referencing.
124 +)))
125 +1. (((
126 +**Data Conversion**
127 +
128 +* Convert the raw DAS time series data from counts to strain rate, which is more meaningful for seismic analysis.
129 +)))
130 +1. (((
131 +**Data Decimation**
132 +
133 +* Reduce the sampling rate from 1000 Hz to 100 Hz. This step is essential to manage data volume and focus on frequencies of interest for seismic activities.
134 +)))
135 +1. (((
136 +**Extract Specific Time Series**
137 +
138 +* Isolate time series data of special interest, such as those related to earthquake events, for detailed analysis.
139 +)))
140 +1. (((
141 +**Data Hosting**
142 +
143 +* Store the processed data on Research School of Earth Sciences (RSES) clusters and the National Computational Infrastructure (NCI) for accessibility and further analysis.
144 +)))
145 +1. (((
146 +**Extract Data and Instrument Response from Seismic Nodes**
147 +
148 +* Retrieve both the raw data and the corresponding instrument response characteristics for accurate interpretation of the seismic signals.
149 +)))
150 +1. (((
151 +**Long-term Archiving and Data Sharing**
152 +
153 +* Ensure that the data is archived in a format and location that supports long-term preservation and accessibility, such as the AuScope Distributed Acoustic Sensing (DAS) Collection.
154 +)))
155 +1. (((
156 +**Data Access and Record Keeping**
157 +
158 +* Maintain records and access paths (e.g., NCI local file path) for the data, including metadata and other associated records, to facilitate future research and data sharing.
159 +)))
160 +
161 +=== ===
162 +
163 +=== ===
164 +
165 +=== ===
166 +
167 +=== ===
168 +
169 +=== ===
170 +
171 +----
172 +
173 += **Silixa iDAS Setup Manual for Reoccupying/Duplicating Experiment** =
174 +
175 += **General Information** =
176 +
177 +* **Experiment Name:** ~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~__
178 +* **Local Date:** ~_~_~_~_/~_~__**/202**
179 +* **Local Time:** ~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~__
180 +* **Personnel:** ~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_
181 +* **Site Condition Notes:**
182 +** [Space for detailed notes about the site condition, any upkeep performed, and changes made since the last visit.]
183 +
184 +----
185 +
186 +==== **Setup Procedure** ====
187 +
188 +1. (((
189 +**Open iDAS Box**
190 +
191 +* Serial Number: ~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~__
192 +* IP Address: ~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_
193 +)))
194 +1. (((
195 +**Check Laser Lock**
196 +
197 +* Ensure the lever on the LASER/RIGHT side of the iDAS is in the locked position (LEVER UP).
198 +)))
199 +1. (((
200 +**Placement of iDAS**
201 +
202 +* Position the iDAS on a stable surface.
203 +* Ensure clear air flow around the fan vents.
204 +)))
205 +1. (((
206 +**UPS Setup** (If applicable)
207 +
208 +* Connect the UPS to a power source.
209 +* Plug the NAS into the UPS using the special cable with a rectangular connector.
210 +* Connect the monitor to the UPS.
211 +)))
212 +1. (((
213 +**Peripheral Connections**
214 +
215 +* Connect a computer monitor, mouse, and keyboard to the iDAS.
216 +)))
217 +1. (((
218 +**GPS Antenna Connection**
219 +
220 +* Connect the GPS antenna to the left-side socket on the front of the iDAS using a special adapter.
221 +)))
222 +1. (((
223 +**Fibre Optic Connection**
224 +
225 +* Clean both the fibre optic cable and the socket with a 1-click cleaner before connection.
226 +* Use the guide/tip for cleaning the fibre and clean the socket without it.
227 +)))
228 +1. (((
229 +**Powering the iDAS**
230 +
231 +* Connect the iDAS to a power socket or UPS.
232 +* Note: The iDAS turns on automatically when connected to power. Use the power button at the bottom left if it does not.
233 +)))
234 +1. (((
235 +**Network Drive Mapping**
236 +
237 +* Open File Explorer and select 'This PC' from the left pane.
238 +* On the File Explorer ribbon, select 'More' > 'Map network drive'.
239 +* Choose a drive letter from the 'Drive' list.
240 +)))
241 +1. (((
242 +**Open iDAS Software**
243 +
244 +* Use the link/shortcut on the Desktop.
245 +)))
246 +1. (((
247 +**GPS Satellite Confirmation**
248 +
249 +* Check for a green light in the top row of the software interface indicating GPS satellite detection.
250 +)))
251 +1. (((
252 +**Lever/Interlock Adjustment**
253 +
254 +* Lower the lever/interlock (as mentioned in step 2) before starting data acquisition.
255 +)))
256 +1. (((
257 +**Configuration File Duplication**
258 +
259 +* Use 'current.cfg' for duplicating previous setup.
260 +* The file is located at C:/Silixa/Data/current.cfg.
261 +* Copy this file to the desktop and save it with a new filename.
262 +)))
263 +1. (((
264 +**iDAS Configuration Settings**
265 +
266 +* Navigate to the 'Configuration' tab and click 'iDAS configuration'.
267 +* Check all values under 'system'.
268 +* Under 'application', enable error messages.
269 +* In 'saving', select 'acoustic saving', choose 'tdms', and set the file save location and identifier.
270 +* Leave default parameters in 'measure'.
271 +)))
272 +1. (((
273 +**Mode Selection**
274 +
275 +* Toggle between Acoustic mode, Waterfall mode, and OTDR mode to check data recording.
276 +)))
277 +1. (((
278 +**Photograph OTDR Mode**
279 +
280 +* Document the OTDR mode settings with a photograph.
281 +)))
282 +1. (((
283 +**Photograph Waterfall Mode**
284 +
285 +* Similarly, take a picture of the Waterfall mode settings.
286 +)))
287 +1. (((
288 +**Configuration File Saving**
289 +
290 +* Save the configuration file in .cfg format in a separate location without overwriting the existing one.
291 +)))
292 +1. (((
293 +**Software Check**
294 +
295 +* Ensure QFinder, Teamviewer, and Microsoft Remote Desktop are installed.
296 +)))
297 +1. (((
298 +**Remote Access Setup**
299 +
300 +* Open Teamviewer or Microsoft Remote Desktop.
301 +* For Teamviewer, photograph the ID and password and ensure it remains open.
302 +* For Microsoft Remote Desktop, record the IP address and test remote access with a separate laptop.
303 +)))
304 +1. (((
305 +**Final Mode Setting**
306 +
307 +* Switch to OTDR mode for ongoing operation (avoids excessive memory usage of Waterfall mode).
308 +)))
309 +
310 +----
311 +
312 +==== **Important Reminders** ====
313 +
314 +* Always ensure that the iDAS is connected to a suitably earthed power socket or UPS for safety.
315 +* Regularly check the condition of all cables and connectors.
316 +* Before leaving the setup, confirm that data saving is active if required.
317 +* Keep a log of all actions taken during the setup for future reference and troubleshooting.
318 +
319 +
320 +
321 +
322 +
323 +
324 +
325 +
326 +
327 +
328 +[[Caption>>image:1706488806394-168.png]]
329 +
330 +
331 +[[image:https://photos.fife.usercontent.google.com/pw/ABLVV86phmYsze0lp1yzL-gs6stE23rmgKbOxcpCRhFmK9s25zf5UHBkgbFcOg=w1440-h2556-s-no-gm?authuser=0]]
332 +
333 +
334 +
335 +[[How to clean the optical connector>>image:1706488909085-143.png||alt="How to clean the optical connector"]]
336 +
337 +
338 +
339 +
340 +
341 +
342 +
343 +
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352 +
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