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edited by Sima Mousavi
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on 2024/01/25 15:00
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1 -Distributed Acoustic Sensing (DAS)
1 +Distributed Acoustic Sensing
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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 -(% class="box warningmessage" %)
9 -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.
10 -\\Cables and fibers may create tripping hazards. Ensure that the routing of cables is done in a way that minimizes the risk of accidents.
11 -
12 -----
13 -
14 -=== **System Components** ===
15 -
16 -**Interrogator Unit**
17 -
18 -* 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.
19 -
20 -**Optical Fiber**
21 -
22 -* This component acts as a long, distributed sensor. Strain rates along this fiber are what the iDAS system measures and analyzes.
23 -
24 -**Data Acquisition Software**
25 -
26 -* This software interfaces with the interrogator unit, allowing users to configure acquisition parameters, initiate data capture, and process the collected data.
27 -
28 -= =
29 -
30 -= =
31 -
32 -= **DAS Data Collection System** =
33 -
34 -==== **1. Interrogator Unit** ====
35 -
36 -* **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.
37 -* **Recording Information:** It records various settings such as the optical system configurations, spatial sampling rates, and the duration of data acquisition.
38 -* **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.
39 -
40 -==== **2. Surface Installation** ====
41 -
42 -* **Cable Arrangement:** The optical fiber cable can be a single long continuous cable or multiple cables with connectors, used across different installation environments.
43 -* **Cable Types:** Cables may vary in construction types based on the installation environment.
44 -* **Geographical Metadata:** Parameters related to geographical location are specified for easy searchability in databases.
45 -
46 -==== **3. Fiber Optic Cable** ====
47 -
48 -* **Cable Composition:** Several optical fibers may be enclosed within one cable.
49 -* **Metadata Identification:** The metadata identifies each individual fiber used in the acquisition, including its intrinsic properties.
50 -
51 -==== **4. Installation Environments** ====
52 -
53 -* **Shallow Burial:** The cable can be shallowly buried.
54 -* **In-Conduit Installation:** The cable can also be installed within a conduit.
55 -* **Water Installation:** Suitable for underwater environments.
56 -
57 -==== **5. Channels** ====
58 -
59 -* **Sensor Distribution:** Channels represent sensors distributed along the fiber array at fixed intervals.
60 -* **Physical Location Determination:** The physical locations of these channels are ascertainable through methods like tap tests and GPS tracking.
61 -* **Metadata for Channels:** Each channel or group of channels has its own metadata block, detailing specifics like location and properties.
62 -
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 -
329 -[[Caption>>image:1706488806394-168.png]]
330 -
331 -
332 -[[image:https://photos.fife.usercontent.google.com/pw/ABLVV86phmYsze0lp1yzL-gs6stE23rmgKbOxcpCRhFmK9s25zf5UHBkgbFcOg=w1440-h2556-s-no-gm?authuser=0]]
333 -
334 -
335 -
336 -[[How to clean the optical connector>>image:1706488909085-143.png||alt="How to clean the optical connector"]]
337 -
338 -
339 -
340 -
341 -
342 -
343 -
344 -
345 -
346 -
347 -
348 -
349 -
350 -
351 -
352 -
353 -
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