Geomatrix Earth Science Ltd
Fast resistivity measurements without probes The new Geometrics OhmMapper is a capacitively coupled resistivity meter that measures the electrical properties of rocks and soil without cumbersome ground stakes used in traditional resistivity surveys.
A simple coaxial-cable array with transmitter and receiver sections is pulled along the ground either by a single person or attached to an all-terrain vehicle. Data collection is many times faster than systems using conventional DC resistivity.
Technical Specifications
| Operating Principle | Constant-current, capacitively coupled, dipole-dipole resistivity |
| Operating Range | From <3 to > 100,000 Ohm-meters |
| Cycle Rate | Selectable data logging rate up to 2 times per second |
| Data Storage | 2 MB of non-volatile RAM |
| Audio Output | Metronome, signal amplitude, error alarm |
| Visual Output |
320 by 200 graphic LCD display, daylight visible with selectable outputs for: 1. Data display: 5 line profiles of resistivity |
| Weights | Console: 1.6 Kg Transmitter with batteries: 3.2 Kg Receiver with batteries: 3.2 Kg Battery pack/harness: 1.6 Kg Depressor weight: 3.2 Kg Dipole cables: 85 g/metre |
| Transmitter Specifications | Frequency: approx. 16.5 kHz Output power: up to 2 Watts Output current maximum: 16 mA Output current minimum: 0.125 mA |
| Receiver Specifications | Cable lengths: 5m standard (x4) Input impedance: >5 M Ohm Measured voltage accuracy: Better than 3% Input voltage range: 0-2 V RMS Power line rejections: >100 dB |
| Dimensions | Console: 15 x 8 x 28 cm Battery: 8 x 13 x 20 cm |
| Battery | 1. Transmitter/Receiver - 2x6 VDC (12 VDC) 2. Console - 28 VDC 3. Internal battery backup for clock and non-volatile RAM |
| Environmental | Temperature: -25 C to +50C Note: At less than -10 C the LCD screen must be kept warm |
| Internal Clock | Resolution of 0.1 drift <1 second/day |