OhmMapper
from Geometrics
Fast resistivity measurements without probes. The 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.
The receivers automatically synchronise to the transmitter cycle, allowing the transmitter/receiver offset to be quickly adjusted in the field for multi depth investigations.
The OhmMapper can be operated using the Geometrics console or a Windows or Android application (OhmLog) via Bluetooth. OhmLog offers the operator additional reliability and flexibility.
The OhmMapper is used predominantly for mapping geological variation, contaminant plumes, hydrological studies, and for precision agriculture.
Technical Specifications
| Operating Principle: | Constant-current, capacitively coupled, dipole-dipole resistivity |
|---|---|
| Operating Range: | Selectable data logging rate up to 2 times per second |
| Communication: | Bluetooth |
| Data Storage: | On a Geometrics console or Windows/ android tablet. |
| Audio Output: | Metronome, signal amplitude, error alarm |
| Visual Output: | 1. Data display: up to 5 line profiles of resistivity
2. All system setup functions 3. All survey functions: survey profile number and direction, station or GPS number, test line number 4. Survey monitor functions 5. Survey diagnostics |
| 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 |
| 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 |
Shipping
Shipping Notes:
Shipped in two transit cases:
Transit case 1: 62 x 5 x 20 cm; 11.1kg ( backpack and Bluetooth assembly)
Transit case 2: 78 x 58 x 41cm; 50.9kg
Data Sheet
- OhmMapper Datasheet (PDF)
Literature
- OhmMapper Theory of Operation (PDF 177KB)
Checklists
- Checklist for Data Storage and Transfer (PDF 249KB)
- Checklist for Data Processing (PDF 190KB)
- Checklist for Field Editing (PDF 244KB)
- Checklist for GPS Operating Procedures (PDF 231KB)
- Checklist for Instrument Storage (PDF 138KB)
- Checklist for Out of Box Equipment Tests (PDF 228KB)
