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.
| GT-40 |
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 |
