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60-Channel Array-Based Electrical System (ERT + AMT) | 3000V/10A | 500m Depth
PRODUCT PARAMETERS
Description
Overview
OverviewThe 60-channel array-based electrical resistivity tomography (ERT) and audio-magneto-telluric (AMT) integrated system synergistically combines the strengths of both methodologies to establish a dual-resolution geophysical detection framework—featuring high-resolution imaging of shallow subsurface structures and broadband characterization of deeper geological formations.
Features
1. Dual-Resolution Detection Framework
The system synergistically combines ERT and AMT methodologies. ERT delivers high-resolution imaging of shallow structures to approximately 200m. AMT extends detection to 500m using natural electromagnetic fields. This dual-resolution approach eliminates the depth gap between conventional DC methods and deep exploration techniques. A single deployment covers the full investigation range.
2. High-Power Transmission, Up to 3000V/10A
The transmitter delivers standard output of 1000V/5A. Maximum power reaches 5kW, expandable to 30kW with external power source. Maximum voltage reaches 3000V. Maximum current reaches 10A. This high-power output ensures sufficient signal penetration in high-resistivity formations. Deep ore bodies, groundwater aquifers, and bedrock structures at 500m depth are detectable.
3. 32-Bit ADC High-Precision Acquisition
The receiver adopts 32-bit A/D conversion module. Measuring voltage range is ±4.5V. Voltage resolution reaches 0.1μV. Voltage accuracy is ±0.1% ± 1 digit. Polarization accuracy is ±0.2%. Input impedance is 50MΩ. The system provides 4 secondary field time windows for IP decay analysis. Stack times are selectable from 1 to 10. 50Hz power frequency suppression exceeds 80dB.
4. 60-Channel Centralized Cable, Stable and Durable
The system includes a 60-channel electrode converter unit. Classic centralized cable architecture simplifies field deployment. Cables are designed for rugged field conditions. Damage resistance is significantly improved compared to distributed wireless systems. Large-scale 2D profiles and 3D grids are efficiently covered. Electrode arrays including Wenner, Schlumberger, dipole-dipole, and pole-dipole are fully supported.
5. Dual Synchronization Modes
The transmitter supports both software synchronization and GPS synchronization. Software sync suits short-distance wired ERT setups. GPS sync enables long-offset AMT configurations over large areas. Flexibility is ensured for diverse terrain and survey scales.
6. Real-Time Data Management
The transmitter features USB communication interface. Current storage time interval is adjustable from 1 to 30 minutes. The receiver displays real-time data on a 4.3-inch 24-bit true color LCD. Field operators can verify data quality instantly. The transmitter uses a 5-inch 24-bit true color LCD for parameter monitoring.
Technical Principles
The 60-Channel ERT + AMT System operates on two complementary electromagnetic methods.
ERT (Electrical Resistivity Tomography) injects direct current into the ground through current electrodes. Potential differences are measured across potential electrodes. Apparent resistivity is calculated for each electrode configuration. 2D or 3D resistivity models are obtained through iterative inversion. ERT excels at high-resolution shallow imaging.
AMT (Audio Magnetotelluric) measures natural electromagnetic fields in the audio-frequency range (1Hz to 50kHz). Orthogonal electric and magnetic field components are recorded. The impedance tensor is computed. Apparent resistivity and phase are derived. AMT requires no artificial current source. It is effective for deep sounding to 500m.
| Method | Source | Frequency | Depth Range | Resolution | Best Application |
|---|---|---|---|---|---|
| ERT | Artificial DC current | DC | 0-200m | High | Shallow structure, groundwater, engineering |
| AMT | Natural EM fields | 1Hz-50kHz | 100-500m | Medium | Deep structure, basement, geothermal |
| ERT+AMT | Combined | DC + 1Hz-50kHz | 0-500m | High + Medium | Seamless shallow-to-deep coverage |
The integrated system acquires both datasets simultaneously. Joint inversion produces a unified resistivity model from surface to 500m depth.
Specifications
The 60-Channel ERT + AMT System comprises three core components. High-Power DC IP Transmitter. High-Precision Multi-Channel Receiver. 60-Channel Electrode Converter Unit with AMT Sensors.
1. High-Power DC IP Transmitter
| Parameter | Specification |
|---|---|
| Transmitting power | 5kW (max 30kW with external source) |
| Transmitting voltage | ±1000V (max 3000V) |
| Transmitting current | 5A (max 10A) |
| Current measurement accuracy | ±1% |
| Power supply cycle | 1s to 128s |
| Current storage interval | 1 to 30 minutes |
| Communication interface | USB |
| Synchronization mode | Software sync, GPS sync |
| Output band | Bipolar, duty cycle 1:1 |
| Display | 5-inch 24-bit true color LCD |
| Operating temperature | -10℃ to +50℃, humidity 95% |
| Storage temperature | -20℃ to 60℃ |
2. High-Precision Multi-Channel Receiver
| Parameter | Specification |
|---|---|
| Measuring voltage range | ±4.5V |
| Measuring voltage resolution | 0.1μV |
| Measuring voltage accuracy | ±0.1% ± 1 digit |
| Adaptable power supply time | 1s, 2s, 4s, 8s, 16s, 32s, 64s, 128s |
| Polarization accuracy | ±0.2% |
| Stack | 1 to 10 times selectable |
| Power-off delay | 50 to 500ms in ten steps |
| 50Hz power frequency suppression | >80dB |
| Input impedance | 50MΩ |
| Secondary field time window number | 4 |
| Synchronization mode | Software synchronization |
| Display | 4.3-inch 24-bit true color LCD |
3. 60-Channel Electrode Converter Unit with AMT Sensors
The converter unit manages automatic switching among 60 electrodes for ERT acquisition. AMT magnetic and electric field sensors are integrated into the same platform. Standard electrode spacing is customizable. Array configurations include Wenner, Schlumberger, dipole-dipole, and pole-dipole. The centralized cable design ensures signal integrity. AMT sensors use negative feedback amplification technology for stable frequency response.
Applications
1. Mineral Exploration
Rapidly delineate disseminated sulfide ore bodies. Identify chargeable zones associated with copper, lead-zinc, and gold deposits. ERT maps shallow alteration zones at high resolution. AMT extends detection to deep-seated mineralization at 300-500m. 3D resistivity and chargeability models guide drill targeting. Exploration risk is significantly reduced.
2. Groundwater Exploration
Map aquifer geometry and fracture zones. Distinguish freshwater from saline water through resistivity contrast. ERT provides detailed shallow aquifer characterization. AMT identifies deep bedrock aquifers and fault-controlled water systems. Well placement is optimized based on integrated geophysical models.
3. Geotechnical Engineering
Investigate subsurface conditions for foundation design. Detect cavities, faults, and weak zones. Monitor landslide slip surfaces. ERT provides high-resolution 2D/3D resistivity images to 200m. AMT extends to bedrock depth and deep structural features. Engineering decisions are supported by quantitative geophysical data.
4. Environmental Site Assessment
Map contaminant plumes from landfills and industrial sites. Track groundwater pollution migration. Identify buried drums and underground storage tanks. ERT resolves shallow contamination at meter-scale resolution. AMT detects deep plume migration pathways. Non-invasive surveys minimize environmental disturbance.
5. Geothermal Exploration
Identify geothermal reservoir boundaries. Map fault and fracture networks controlling fluid flow. ERT characterizes shallow cap rock and alteration zones. AMT probes deep heat sources and conductive pathways. Combined interpretation achieves 500m investigation depth. Temperature anomalies are inferred from resistivity patterns.
Cases
Case 1: 2D Resistivity + AMT Joint Survey for Deep Groundwater
A groundwater exploration project required investigation from surface to 500m depth. Conventional ERT equipment could only reach 200m. The 60-Channel ERT + AMT System was deployed. ERT with 60 electrodes at 5m spacing provided high-resolution shallow data. AMT sensors recorded natural EM fields for deep sounding. Joint inversion produced a unified resistivity section from 0 to 500m. Deep conductive zones were interpreted as fractured bedrock aquifers. Drilling confirmed water-bearing formations at 350m and 480m. The integrated approach avoided the cost of separate surveys.
Case 2: Mineral Exploration with Expanded Detection Depth
A mineral exploration project targeted concealed ore bodies below 300m. Standard IP/ERT systems lacked sufficient depth penetration. The 60-Channel ERT + AMT System was deployed with high-power transmission at 2500V/8A. ERT data mapped shallow conductive overburden. AMT data revealed a deep low-resistivity anomaly at 400-500m. The anomaly was interpreted as a sulfide mineralization zone. Follow-up drilling intersected economic-grade ore at 420m. The ERT + AMT integration proved essential for deep target identification.
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.
