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