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Summary

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Title
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1 -Distributed Acoustic Sensing (DAS)
1 +integrated Distributed Acoustic Sensing (iDAS)
Content
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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 +
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 +
3 3  ----
4 4  
5 -==== **General Information** ====
15 +=== **System Components** ===
6 6  
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 +* **Cable Arrangement:** The optical fiber cable can be a single long continuous cable or multiple cables with connectors, used across different installation environments.
31 +* **Cable Types:** Cables may vary in construction types based on the installation environment.
32 +* **Geographical Metadata:** Parameters related to geographical location are specified for easy searchability in databases.
33 +
34 +==== **2. Installation Environments** ====
35 +
36 +* **Shallow Burial:** The cable can be shallowly buried.
37 +* **In-Conduit Installation:** The cable can also be installed within a conduit.
38 +* **Water Installation:** Suitable for underwater environments.
39 +
40 +==== **3. Channels** ====
41 +
42 +* **Sensor Distribution:** Channels represent sensors distributed along the fiber array at fixed intervals.
43 +* **Physical Location Determination:** The physical locations of these channels are ascertainable through methods like tap tests and GPS tracking.
44 +* **Metadata for Channels:** Each channel or group of channels has its own metadata block, detailing specifics like location and properties.
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 +
7 7  * **Experiment Name:** ~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~__
8 8  * **Local Date:** ~_~_~_~_/~_~__**/202**
9 9  * **Local Time:** ~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~_~__
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