With GT-40, the receiving probe is lowered into the borehole while a large surface loop transmits; the borehole acquires the secondary field segment by segment at each depth, specializing in fine geological / hydrogeological detection ahead of the tunnel face and along the tunnel sidewalls.
Geological / hydrogeological detection ahead of the tunnel face and along tunnel sidewalls in mines, subways, high-speed railways, highways, water conservancy, etc.; identification of water-bearing structures, fractured zones and cavities at successive depth segments inside boreholes; water-bearing prediction in advanced sidewall boreholes; delineation of ore-body / anomaly boundaries in core boreholes; fine depth resolution and anomaly localization around existing boreholes.
A lightweight receiving probe of 5 cm diameter and 55 cm length can be lowered into conventional engineering boreholes and core boreholes; geological anomalies are reconstructed segment by segment along borehole depth, no longer indirect inference from surface projection.
In the central-loop working mode, the transmitter loop and the in-hole probe are geometrically orthogonal, so the primary field couples negligibly at the probe position and the remaining secondary field is not masked by primary-field residues.
The probe is compatible with ≥150 A high-current transmitter systems, exciting a strong enough secondary field; weak anomalies such as water-filled fractures, low-resistivity aquifers and fractured zones respond rapidly.
The receiving probe is independent, lightweight and compact; the accompanying cable is designed for borehole conditions, and the risks of borehole-wall squeeze and hoisting are more controllable than with bulky probes.
| Parameter | GT-40 |
|---|---|
| A/D Converter | 32Bit |
| Dynamic Range | 160dB |
| Sampling Rate | 1μs、4μs、16μs、 |
| Number of Acquisition Channels | 2 |
| Noise Floor | 1μV |
| Voltage Measurement Range | -200V-200V |
| Voltage Measurement Resolution | ≤300nV |
| Measurement Accuracy | 0.001 |
| Input Gain Range | 1/80-8000 |
| Minimum Sampling Interval | 4μs |
| Noise Suppression | >100dB |
| Passband | 0-500kHz |
| Stacking Times | 200 |
| Dimensions | 403mm×330mm×178mm (L×W×H) |
| Weight | 8kg |
| Operating Temperature | -10℃-50℃ |
| Transmit Voltage (V) | 36-57 |
| Transmit Current (A) | 25、50、100、200 |
| Current Pulse Width (ms) | 10、20、40 |
| Transmit Waveform | Bipolar square wave with 1:1 duty cycle |
| Max Transmit Power (kW) | 3.6 |
| Turn-off Time | 0.5-300μs |
| Parameter | Receiver Module | Parameter | Transmitter Module |
|---|---|---|---|
| A/D Converter | 32-bit | Transmitter Voltage (V) | 36-57 |
| Dynamic Range | 160dB | Transmitter Current (A) | ≥150 |
| Sampling Rate | 1μs、4μs、16μs | Current Pulse Width (ms) | 10、20、40 |
| Number of Acquisition Channels | 2 | Transmitted Waveform | Bipolar square wave with a 1:1 duty cycle |
| Background Noise | 1μV | Maximum Transmitter Power (kW) | 8.5 |
| Voltage Measurement Range | -200V-200V | Synchronization Method | Cable synchronization |
| Voltage Measurement Resolution | ≤300nV | Turn-off Time | 0.5–300 μs, depending on the supply current and transmitter coil |
| Measurement Accuracy | 0.001 | Computer System | Windows-based operating interface |
| Input Gain Range | 1/80-8000 | Data Interface | USB2.0 |
| Minimum Sampling Interval | 4μs | Storage Capacity | ≥30,000 measurement points |
| Noise Suppression | >100dB | Dimensions (L × W × H) | 403mm×330mm×178mm |
| Frequency Bandwidth | 0-500kHz | Weight | 8kg |
| Stacking Times | 1~200 | Operating Temperature | -10℃-50℃ |
| Parameter Category | GT-40 |
|---|---|
| System Positioning | Borehole TEM system for downhole exploration |
| Standard Transmitter Loop Specification | General compatible range: 1 m × 1 m to 10 m × 10 m square loops; custom sizes available |
| Standard Receiver Probe / Coil | Lightweight receiver probe, 5 cm in diameter and 55 cm long |
| Common Survey Configuration | Central-loop configuration |
| Compatible Transmitter Current | Compatible with transmitter currents of ≥150 A for rapid identification of anomalous zones |
| Typical Applications | Geological and hydrogeological investigations ahead of tunnel faces and along tunnel sidewalls in mines, metro systems, high-speed railways, highways, and water-conservancy projects |
| Design Features | Independent receiver probe with a compact, lightweight design |
| Name | Model | Code |
|---|---|---|
| GT-40 Standard Kit | GT-40 Kit | M0.0017 |
| Transient Electromagnetic Instrument | GT-40 | M0.2004 |
| Industrial Tablet PC (including Network Cable) | ONERugged | M6.0001 |
| Ground TEM Probe | T-10 | M4.2001 |
| Transmitter Loop | 6mm²*40m | M4.2002 |
| Ground TEM Probe Connection Cable | T-11 | M6.0014 |
| Processing Software (including USB Dongle) | TEM Processing Software | M5.1010 |
| TEM Backpack Harness | Dual-Shoulder | M6.0006 |
| TEM Charger | CDQ-5 | M4.1005 |
| Tablet PC Charger | CDQ-6 | M4.1006 |
| Borehole Probe | T-40 | M4.2013 |
| Borehole TEM Probe Connection Cable | T-41 | M6.0065 |
