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Last modified by robert on 2024/05/17 16:52
From version 6.2
edited by Sima Mousavi
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To version 7.1
edited by Sima Mousavi
on 2024/01/29 14:41
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1 -=== **Silixa iDAS Setup Manual for Reoccupying/Duplicating Experiment** ===
1 += **What is iDAS?** =
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.
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 +
3 3  ----
4 4  
5 -==== **General Information** ====
14 +=== **System Components** ===
6 6  
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 +
7 7  * **Experiment Name:** ~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~__
8 8  * **Local Date:** ~_~_~_~_/~_~__**/202**
9 9  * **Local Time:** ~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~__
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