channelgroup.md

Channel Group Metadata

• The Channel Group metadata describes the properties that are common to all the channels nested under the Interrogator and Acquisition metadata blocks. Having a group-level metadata removes the repetition of common attributes in the individual Channel metadata. This design allows multiple channel groups to exist under the same interrogator and data acquisition settings. The unique identifiers for the interrogator, acquisition, cable and fiber are recorded as well in this metadata block to allows mapping between the interrogator, acquisition, and fiber that were used for this set of coordinates during a particular data collection.

• Required fields (mark with an asterisk, and indicated in the tables below)
  channel_group_id* | interrogator_id* | acquisition_id* | cable_id* | fiber_id* | coordinate_generation_date* | coordinate_system* | reference_frame* | location_method* | distance_along_fiber_unit* | x_coordinate_unit* | y_coordinate_unit*

• Optional fields
  uncertainty_in_x_coordinate | uncertainty_in_x_coordinate_unit | uncertainty_in_y_coordinate | uncertainty_in_y_coordinate_unit | elevation_above_sea_level_unit | uncertainty_in_elevation | uncertainty_in_elevation_unit | depth_below_surface_unit | uncertainty_in_depth | uncertainty_in_depth_unit | strike_unit | uncertainty_in_strike | uncertainty_in_strike_unit | dip_unit | uncertainty_in_dip | uncertainty_in_dip_unit | first_usable_channel_id | last_usable_channel_id | comment

---

channel_group_id

attributeID	channel_group_id Required
Description	Unique identifier of the channel group. Identifier should have a maximum of 8 alphanumeric characters with no special characters (e.g., underscores, period, dash).
Required	True
Type	String
Style	Alphanumeric
Units or options	--
Example	CG001

interrogator_id

attributeID	interrogator_id Required
Description	Unique identifier of interrogator used corresponding to this channel group.
Required	True
Type	String
Style	Alphanumeric
Units or options	--
Example	IU001

acquisition_id

attributeID	acquisition_id Required
Description	Unique identifier of data acquisition metadata block used to set this channel group. The acquisition_id must nest within specified interrogator_id.
Required	True
Type	String
Style	Alphanumeric
Units or options	--
Example	A001

cable_id

attributeID	cable_id Required
Description	Unique identifier of cable linked to this channel group.
Required	True
Type	String
Style	Alphanumeric
Units or options	--
Example	CA001

fiber_id

attributeID	fiber_id Required
Description	Unique identifier of fiber linked to this channel group. The fiber_id must nest within specified cable_id.
Required	True
Type	String
Style	Alphanumeric
Units or options	--
Example	F001

coordinate_generation_date

attributeID	coordinate_generation_date Required
Description	Date that the channel coordinates were generated.
Required	True
Type	String
Style	ISO formatted datetime
Units or options	--
Example	2016-07-01T00:00:00.000Z

coordinate_system

attributeID	coordinate_system Required
Description	Coordinate system used in channel location. Select geographic for coordinates in latitude and longitude. UTM is the preferred projected coordinate system.
Required	True
Type	String
Style	Controlled vocabulary
Units or options	[geographic
Example	UTM

reference_frame

attributeID	reference_frame Required
Description	Geodetic datum and / or grid zone number in UTM.
Required	True
Type	String
Style	Controlled vocabulary
Units or options	[WGS84
Example	UTM Zone 11N

distance_along_fiber_unit

attributeID	distance_along_fiber_unit Required
Description	Unit of distance along fiber.
Required	True
Type	String
Style	Controlled vocabulary
Units or options	meter
Example	meter

x_coordinate_unit

attributeID	x_coordinate_unit Required
Description	Unit of x-coordinate (UTM-x or longitude). Applies to every individual channel nested under the channel group.
Required	True
Type	String
Style	Controlled vocabulary
Units or options	[decimal degree
Example	meter

y_coordinate_unit

attributeID	y_coordinate_unit Required
Description	Unit of y-coordinate (UTM-y or latitude). Applies to every individual channel nested under the channel group.
Required	True
Type	String
Style	Controlled vocabulary
Units or options	[decimal degree
Example	meter

location_method

attributeID	location_method Optional
Description	Method used to determine the coordinates of each channel. Example: tap test, GPS tracker.
Required	False
Type	String
Style	Free form text
Units or options	[tap test
Example	tap test

uncertainty_in_x_coordinate

attributeID	uncertainty_in_x_coordinate Optional
Description	Uncertainty in the x-coordinate (UTM-x or longitude), representing the average uncertainty for all the channels.
Required	False
Type	Float
Style	na
Units or options	-
Example	-

uncertainty_in_x_coordinate_unit

attributeID	y_coordinate_unit Optional
Description	Unit of uncertainty in x-coordinate.
Required	False
Type	String
Style	Controlled vocabulary
Units or options	meter
Example	meter

uncertainty_in_y_coordinate

attributeID	uncertainty_in_y_coordinate Optional
Description	Uncertainty in the y-coordinate, representing the average uncertainty for all the channels.
Required	False
Type	Float
Style	na
Units or options	-
Example	-

uncertainty_in_y_coordinate_unit

attributeID	uncertainty_in_y_coordinate_unit Optional
Description	Unit of uncertainty in y-coordinate.
Required	False
Type	String
Style	Controlled vocabulary
Units or options	meter
Example	meter

elevation_above_sea_level_unit

attributeID	elevation_above_sea_level_unit Optional
Description	Unit of elevation above sea level. Applies to every individual channel nested under the channel group.
Required	False
Type	String
Style	Controlled vocabulary
Units or options	meter
Example	meter

uncertainty_in_elevation

attributeID	uncertainty_in_elevation Optional
Description	Uncertainty in elevation above sea level, representing the average uncertainty in elevation for all the coordinates.
Required	False
Type	Float
Style	na
Units or options	-
Example	-

uncertainty_in_elevation_unit

attributeID	uncertainty_in_elevation_unit Optional
Description	Unit of uncertainty in elevation.
Required	False
Type	String
Style	Controlled vocabulary
Units or options	meter
Example	meter

depth_below_surface_unit

attributeID	depth_below_surface_unit Optional
Description	Unit of depth below surface. Applies to every individual channel nested under the channel group.
Required	False
Type	String
Style	Controlled vocabulary
Units or options	meter
Example	meter

uncertainty_in_depth

attributeID	uncertainty_in_depth Optional
Description	Uncertainty in depth below surface, representing the average uncertainty in depth for all the coordinates.
Required	False
Type	Float
Style	na
Units or options	-
Example	-

uncertainty_in_depth_unit

attributeID	uncertainty_in_depth_unit Optional
Description	Unit of uncertainty in depth.
Required	False
Type	String
Style	Controlled vocabulary
Units or options	meter
Example	meter

strike_unit

attributeID	strike_unit Optional
Description	Unit of strike. Defined at channel group level as it applies to every individual channel nested under the channel group.
Required	False
Type	String
Style	Controlled vocabulary
Units or options	degree
Example	-

uncertainty_in_strike

attributeID	uncertainty_in_strike Optional
Description	Uncertainty in the strike.
Required	False
Type	Float
Style	na
Units or options	-
Example	-

uncertainty_in_strike_unit

attributeID	uncertainty_in_strike_unit Optional
Description	Unit of uncertainty in strike.
Required	False
Type	String
Style	Controlled vocabulary
Units or options	degree
Example	-

dip_unit

attributeID	dip_unit Optional
Description	Unit of dip. Defined at channel group level as it applies to every individual channel nested under the channel group.
Required	False
Type	String
Style	Controlled vocabulary
Units or options	degree
Example	-

uncertainty_in_dip

attributeID	uncertainty_in_dip Optional
Description	Uncertainty in the dip.
Required	False
Type	Float
Style	na
Units or options	-
Example	-

uncertainty_in_dip_unit

attributeID	uncertainty_in_dip_unit Optional
Description	Unit of uncertainty in dip.
Required	False
Type	String
Style	Controlled vocabulary
Units or options	degree
Example	-

first_usable_channel_id

attributeID	first_usable_channel_id Optional
Description	The first channel considered physically meaningful. Typically, this will be a few channels after the last channel inside the interrogator. Must match one of the channel ids.
Required	False
Type	Integer
Style	Alphanumeric
Units or options	na
Example	30

last_usable_channel_id

attributeID	last_usable_channel_id Optional
Description	The last channel considered physically meaningful. Typically, an acquisition will add virtual channels at the end of the fiber or the optical path might not reach the end of the fiber and this can be used to cut the dataset into a working set. Must match one of the channel ids.
Required	False
Type	Integer
Style	Alphanumeric
Units or options	na
Example	8650

comment

attributeID	comment Optional
Description	Additional comments.
Required	False
Type	String
Style	Free form text
Units or options	--
Example	na