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GEO EMAP-1 60-Channel Multifunction Array Electromagnetic System | ERT+AMT
PRODUCT PARAMETERS
Description
Abstract
The GEO EMAP-1 60-channel multifunction array electromagnetic system is independently developed by GEOTECH. It innovatively integrates Array Audio-frequency Magnetotellurics (RAMT, 10 Hz–20 kHz) and High-Density Electrical Resistivity Tomography (ERT), enabling simultaneous acquisition of two geophysical datasets via a single electrode deployment — “one field deployment, double data returns”.
This 60-channel standard configuration balances portability and detection capacity, optimized for small-to-medium scale projects such as engineering investigation, municipal prospecting and geohazard assessment. The system supports multi-mode wireless communication via Bluetooth, WiFi and 4G/5G, simplifying array layout across difficult terrain. GNSS pulse-per-second synchronization keeps clock error below 50 nanoseconds, ensuring phase coherence across the full 60-channel array. Combined local magnetic sensing with distributed array measurement effectively suppresses cultural noise and improves deep sounding accuracy, while the distributed cascaded architecture supports flexible expansion up to 120 channels for growing project demands.
Features
Dual-method high efficiency
Array AMT and ERT share one 60-channel electrode array; a single deployment delivers two complete datasets, cutting field work time by nearly half.
GNSS precise synchronization
GNSS pulse sync with clock error under 50 ns maintains consistent phase across all 60 channels, ensuring reliable joint inversion of dual-method data.
Versatile observation modes
Supports 2D/3D ERT & IP surveys (Wenner, Schlumberger and other arrays) plus array AMT sounding, realizing continuous detection from shallow subsurface to deep geological structures.
Multi-mode wireless control
Integrated Bluetooth, WiFi and 4G/5G links adapt to all field conditions; paired with an Android industrial panel for cable-free on-site operation and real-time monitoring.
High-performance magnetic sensing
Wide-band AMT magnetic sensor with 1 Hz–100 kHz frequency range; host unit supports 1 extra magnetic coil for flexible reference measurement.
Scalable cascaded layout
Distributed cascade cabling design; this 60-channel package can be expanded with additional switchers and cables to match longer profiles and 3D survey needs.
Specifications
System Info
| Parameter | Specification |
| Frequency Range | 10 Hz ~ 20 kHz |
| Clock Sync | GNSS pulse sync; error < 50 ns |
| Communication | Bluetooth, WiFi and 4G/5G |
| Magnetic Sensor | 1 Hz ~ 100 kHz AMT mag Sensor; host supports 1 extra Mag coil |
Observe and Expand
| Parameter | Specification |
| Measure Array | 2D/3D ERT and IP; Array AMT |
| Electrode Spacing | 10 m standard; adjustable for AMT survey |
| Channel Configuration | 60 channels (5 × Switch-12 units); supports multi-instrument GNSS sync measurement |
Power and Basic Status
| Parameter | Specification |
| Power | Built-in instrument battery; high-voltage input via DC480 power module |
| Operating Temp. | -20℃ ~ 60℃ |
System Components
GEO EMAP-1 Main Unit
Packaged in a portable waterproof case with built-in lithium battery; supports ERT & IP functions and 1 extra magnetic coil; 4G/5G + Bluetooth dual-mode communication.
| Item | Spec | Quantity |
| Communication | 4G/5G + Bluetooth dual-mode | 1 unit |
| Core Function | ERT / IP / Array AMT | 1 unit |
DC-480 Adjustable DC Lithium Battery Power Supply
10-level adjustable output, maximum 480 V / 2.0 A, providing high-voltage DC for transmission; IP67 rated for field use.
| Item | Spec | Quantity |
| Output voltage | Up to 480 V (10 steps) | 1 unit |
| Max. current | 2.0 A | 1 unit |
Cascade Converter
12-tap non-directional electrode switcher; 1000 V / 4 A rating; lightweight for easy field deployment.
| Item | Spec | Quantity |
| Channels per unit | 12 electrode channels | 5 units (total 60 channels) |
| Rating | 1000 V / 4 A | – |
Android Control Panel
Industrial-grade Android tablet for wireless acquisition control, real-time data monitoring and parameter setting.
| Item | Spec | Quantity |
| System | Android OS | 1 unit |
AMT Magnetic Sensor
Wide-frequency magnetic sensor for audio-frequency magnetotelluric signal acquisition.
| Item | Spec | Quantity |
| Frequency range | 1 Hz ~ 100 kHz | 1 piece |
Cascade Electrode Cable
12-tap cable with 10 m tap spacing, matched with Switch-12 units.
| Item | Spec | Quantity |
| Tap configuration | 12 taps per string | 5 strings |
| Tap spacing | 10 m | – |
Non-polarizing Electrode
30 cm non-polarizing electrodes for stable contact resistance, compatible with cascade cable strings.
| Item | Spec | Quantity |
| Type | Non-polarizing electrode | 60 pieces |
| Length | 30 cm | – |
Survey & Processing Software
Dedicated acquisition control and post-processing software, supporting data quality control and joint inversion visualization.
| Item | Spec | Quantity |
| Function | Acquisition + processing + inversion | 1 license |
System Connection
2D EMAP + RAMT Survey
The 60-channel array supports 2D high-density ERT and array AMT survey with GNSS synchronization, suitable for medium-length profile detection.
3D Survey Capability
Supports simultaneous 2D and 3D resistivity & AMT acquisition, and can be combined with more units for expanded 3D surveys.
Applications
- Engineering investigation and site assessment
- Municipal engineering and archaeological prospecting
- Geohazard prevention and hidden danger detection
- Environmental monitoring and groundwater investigation
- Shallow mineral and geothermal prospecting
- Transportation subgrade and hydraulic engineering detection
Case Studies
GEO EMAP-1 Joint Array AMT + ERT Observation Test (Shibei No.1 profile)
A single electrode layout acquired array AMT and ERT data simultaneously: ERT provides shallow high resolution while AMT reveals deep resistivity structure, cross-validating each other to form a complete electrical section from shallow to deep.
- The 60-channel configuration flexibly adapts to medium-length profiles, delivering dual-method data with one deployment.
- The joint section clearly delineates overburden thickness and bedrock relief.
FAQ
In gravity exploration (SI), what is the unit of gravity? How to convert gravity units between SI and CGS?
① In SI, it is m·s-2, and one percent of it is the international unit abbreviation g.u.;
② Conversion between SI and CGS: 1g.u.=10-1 mGal
What are gravitational field and gravitational potential?
Gravitational field: The space around the earth with gravity is called the gravitational field.
Gravitational potential: The gravitational potential W in the gravitational field is equal to the work done by a particle of unit mass moving from infinity to that point.
What is the normal gravity field of the earth? What are the rules for the change of the normal gravity field with latitude and altitude?
① The normal gravity field of the earth: Assuming that the earth is a rotating ellipsoid (reference plane), the surface is glossy, the internal density is uniform, or it is distributed in concentric layers, the density of each layer is uniform, and the deviation of the shape of the ellipsoid from the geoid is very small, then the gravity field generated by the earth is the normal gravity field.
② The normal gravity value is only related to the latitude, the smallest at the equator and the largest at the poles, with a difference of about 50,000 g.u.; the rate of change of the normal gravity value with latitude is the largest at 45° latitude, and zero at the equator and the poles; the normal gravity value decreases with increasing altitude, and its rate of change is -3.086 g.u.. The main feature of the long-term change is the "westward drift" of the geomagnetic elements, both the dipole field and the non-dipole field drift westward, and have a global nature.
What is the relationship between gravitational field strength and gravitational acceleration?
The gravitational field strength is equal to the gravitational acceleration in both numerical and dimensional terms, and the two are in the same direction. In gravity exploration, all references to gravity refer to gravitational acceleration. The gravitational field strength at a point in space is equal to the gravitational acceleration at that point.
What is gravity exploration?
Gravity exploration is an exploration method that is based on the density difference of rocks and ores. Since density difference will cause local changes in the normal gravity field of the earth (i.e. gravity anomaly), it is used to solve geological problems by observing and studying gravity anomalies.
