time-domain-electromagnetic
A time-domain electromagnetic (TDEM) object represents geolocated, time-stamped TDEM survey data. This data is used extensively in exploration for mineral resources, groundwater investigations, and other fields where the electrical conductivity of subsurface materials provides insight.
Electromagnetic (EM) methods do not require direct contact with the ground. EM methods use the phenomenon of electromagnetic induction to create a subsurface current flow, then measure its dissipation. This provides information about the electrical conductivity/chargeability of the subsurface, by measuring the ease with which induced electrical currents flow in the subsurface and the rate at which the electrical chargeability discharges at rock unit boundaries. Rather than the rock units, it is the porosity and the content in the pores space that influence the conductivity of the rock. EM methods provide a measure of the geometry, dimension and electrical characteristics of the source of the anomalous response.
Electromagnetic (EM) methods do not require direct contact with the ground. EM methods use the phenomenon of electromagnetic induction to create a subsurface current flow, then measure its dissipation. EM methods provide information about the electrical conductivity/chargeability of the subsurface, by measuring the ease with which induced electrical currents flow in the subsurface and the rate at which the electrical chargeability discharges at rock unit boundaries. Rather than the rock units, it is the porosity and the content in the pores space that influence the conductivity of the rock. EM methods provide a measure of the geometry, dimension and electrical characteristics of the source of the anomalous response.
The survey object includes details about the survey type, which can be one of the following:
- GROUND
- AIR
- MOVING_GROUND
- DAGCAP (stands for DoD Advanced Geophysical Classification Accreditation Program)
The geometry_category property is a string value taking one of the following forms describing the transmitter (Tx) and receiver (Rx) geometry:
- STXMRX: The Tx is stationary on the ground and the Rx is towed either on the ground or airborne
- FGTXRX: The Tx and Rx are on the same fixed geometry frame and moving together
- MTXMRX: The Tx is built into the vehicle and the Rx is towed on a separate frame
- STXSRX: The Txs and Rxs are in a fixed geometry and stationary, and frequencies are changed
The gps field indicates the location of a GPS relative to a point of reference.
The channels array includes one or more time-domain-electromagnetic-channel objects. Each channel has properties including the channel index, timing information for the transmissions, IDs for the transmitter and receiver, waveform and gates configuration, loop configuration, statistics, filter parameters, etc.
The line_list array includes one or more survey-line definitions, including the line_number, date, version, and group of the survey. Each survey-line definition indicates the type of survey line (the geometry and intended use), location channels, and the associated channel attribute data.
Properties
time-domain-electromagnetic (v1.1.0)
Time Domain Electromagnetic data.
| Property | Type | Description | Flags |
|---|---|---|---|
| name | String | Name of the object. | ⬆️ ✅ |
| uuid | base-object-properties | Identifier of the object. | ⬆️ ✅ |
| description | String | Optional field for adding additional description to uniquely identify this object. | ⬆️ |
| extensions | Object | Extended properties that may be associated to the object, but not specified in the schema | ⬆️ |
| tags | Object | Key-value pairs of user-defined metadata | ⬆️ |
| lineage | lineage | Information about the history of the object | ⬆️ |
| bounding_box | bounding-box | Bounding box of the spatial data. | ⬆️ ✅ |
| coordinate_reference_system | crs | Coordinate system of the spatial data | ⬆️ ✅ |
| schema | String | ✅ | |
| survey | time-domain-electromagnetic | Survey information. | ✅ |
| geometry_category | String | Geometry category. | ✅ |
| gps | coordinates-3d | Location of GPS relative to point of reference. | ✅ |
| channels | Array[time-domain-electromagnetic-channel] | Channel information. | ✅ |
| line_list | Array[survey-line] | Line list. | ✅ |
Legend
| Flag | Description |
|---|---|
| ⬆️ | Inherited property |
| ✅ | Required property |
