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1 -integrated Distributed Acoustic Sensing (iDAS)
1 +Distributed Acoustic Sensing (DAS)
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1 -= **What is iDAS?** =
1 += **DAS Data Collection System** =
2 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.
3 +==== **1. Interrogator Unit** ====
4 4  
5 -=== **Safety first!** ===
5 +* **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.
6 +* **Recording Information:** It records various settings such as the optical system configurations, spatial sampling rates, and the duration of data acquisition.
7 +* **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.
6 6  
7 -=== ===
9 +==== **2. Surface Installation** ====
8 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 -
18 -The iDAS system consists of the following components:
19 -
20 -1. **Interrogator unit:** This unit houses the laser, detector, and electronics for processing the backscattered light signal. It records various settings such as the optical system configurations, spatial sampling rates, and the duration of data acquisition. 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 -1. **Optical fiber:** The optical fiber is the sensor that is used to measure strain rate.
22 -1. **Data acquisition software**: This software is used to control the interrogator unit and to acquire and process the data. It records various settings such as the optical system configurations, spatial sampling rates, and the duration of data acquisition.
23 -
24 -----
25 -
26 -= **DAS Data Collection System** =
27 -
28 -==== **1. Surface Installation** ====
29 -
30 30  * **Cable Arrangement:** The optical fiber cable can be a single long continuous cable or multiple cables with connectors, used across different installation environments.
31 31  * **Cable Types:** Cables may vary in construction types based on the installation environment.
32 32  * **Geographical Metadata:** Parameters related to geographical location are specified for easy searchability in databases.
33 33  
34 -==== **2. Installation Environments** ====
15 +==== **3. Fiber Optic Cable** ====
35 35  
17 +* **Cable Composition:** Several optical fibers may be enclosed within one cable.
18 +* **Metadata Identification:** The metadata identifies each individual fiber used in the acquisition, including its intrinsic properties.
19 +
20 +==== **4. Installation Environments** ====
21 +
36 36  * **Shallow Burial:** The cable can be shallowly buried.
37 37  * **In-Conduit Installation:** The cable can also be installed within a conduit.
38 38  * **Water Installation:** Suitable for underwater environments.
39 39  
40 -==== **3. Channels** ====
26 +==== **5. Channels** ====
41 41  
42 42  * **Sensor Distribution:** Channels represent sensors distributed along the fiber array at fixed intervals.
43 43  * **Physical Location Determination:** The physical locations of these channels are ascertainable through methods like tap tests and GPS tracking.
44 44  * **Metadata for Channels:** Each channel or group of channels has its own metadata block, detailing specifics like location and properties.
45 45  
46 -[[image:1706489800616-982.png]]
32 +=== ===
47 47  
48 -
49 -
50 -[[image:1706488566274-805.png]]
51 -
52 52  ----
53 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 93  === ===
94 94  
95 95  = **Pre-processing Steps for DAS Data (2.5 months, 90 TB)** =
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142 142  
143 143  === ===
144 144  
145 -----
88 +=== ===
146 146  
147 -== **iDAS Software Overview** ==
90 +=== ===
148 148  
149 -==== **Operating System Compatibility:** ====
92 +=== ===
150 150  
151 -* (((
152 -The iDAS system software is designed to run on the Windows operating system, with the current version compatible with Windows 7.
153 -)))
94 +=== ===
154 154  
155 -==== **Accessing the System:** ====
156 -
157 -* (((
158 -**User Login:** The system is set up to log in automatically as "User", without requiring any credentials.
159 -)))
160 -* **Software Shortcut:** A shortcut to access the iDAS software is conveniently placed on the desktop for easy access.
161 -
162 -==== **Data Acquisition Controls** ====
163 -
164 -* (((
165 -**Start / Stop:** Easily control the start and stop of data acquisition using the current settings.
166 -)))
167 -* **Calibrate Reference:** Recalibrate reference levels as needed.
168 -* **Exit:** Safely exit the iDAS software.
169 -
170 -==== **Configuration iDAS Setup Wizard:** ====
171 -
172 -(% class="wikigeneratedid" %)
173 -Provides a guided, step-by-step process for setting up the iDAS system.
174 -
175 -* (((
176 -**iDAS Configuration:** Access the iDAS configuration window for advanced settings.
177 -)))
178 -* **Trigger Mode:** Opens the trigger configuration window for specific acquisition needs.
179 -
180 -==== **Operating Modes ** ====
181 -
182 -* (((
183 -**Available Modes:** Acoustic, Waterfall, Stacking, Security, and OTDR.
184 -)))
185 -* **Functionality:** Each mode presents the acoustic data from iDAS in unique formats.
186 -* **Detailed Information:** See pages 19-23 of the Standard iDAS manual for comprehensive details on each mode.
187 -
188 -
189 -
190 -=== **Application Type Options** ===
191 -
192 -1. **Diagnostic Setup Only:**
193 -1*. Retrieves current settings for a basic diagnostic overview.
194 -1. **Seismic Application:**
195 -1*. Sets Data Output Frequency to 1000 Hz.
196 -1*. Adjusts Data Output Spatial Resolution to 2 meters.
197 -1. **Flow Monitoring:**
198 -1*. Changes Data Output Frequency to 10,000 Hz.
199 -1*. Sets Data Output Spatial Resolution to 0.25 meters.
200 -1. **Security Monitoring:**
201 -1*. Configures Data Output Frequency to 1000 Hz.
202 -1*. Sets Data Output Spatial Resolution to 2 meters.
203 -
204 -
205 -[[image:1706508500303-165.png]]
206 -
207 -
208 -=== **Detailed Parameter Information** ===
209 -
210 -1. **Time Decimation and Output Decimation:**
211 -1*. These values are calculated based on the physical fiber length.
212 -1. **Measure Length (m):**
213 -1*. Generated value: 10176 meters.
214 -1*. Note: 'Measure Length' includes the reference fiber inside the iDAS unit, differentiating it from 'Physical Fibre Length'.
215 -1. **Pulse Width (ns):**
216 -1*. Generated value: 50 nanoseconds.
217 -1*. Spatial Extent: A 50ns pulse corresponds to a 10m spatial extent.
218 -
219 -
220 -[[image:1706508761205-307.png]]
221 -
222 -
223 -
224 -
225 -
226 -=== **Optimal Light Management** ===
227 -
228 -* **Objective:** Achieve balanced light distribution across the region of interest in the iDAS system.
229 -
230 -=== **Adjustment Guidelines** ===
231 -
232 -1. **Setting Optical Power:**
233 -1*. Aim to have the start of the region of interest around or below +4000 units.
234 -1*. Ensure the far end of the region of interest does not enter a non-linear response scheme.
235 -1. **Consideration for Short Fibers:**
236 -1*. In cases where the fiber length is short and non-linear effects are not observed, set the Optical Power to its maximum.
237 -1*. **Power Scale:** The adjustment slider ranges from 0-100, representing the percentage of maximum power available.
238 -
239 -=== **Note on Optical Power Control** ===
240 -
241 -* **Control Mechanism:** The slider provides a precise control mechanism to manage the intensity of light sent through the fiber.
242 -* **Monitoring and Adjustment:** Continuously monitor and adjust as necessary to ensure optimal performance.
243 -
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274 -
275 275  ----
276 276  
277 277  = **Silixa iDAS Setup Manual for Reoccupying/Duplicating Experiment** =
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