T-VLF System


  • Lightweight system weighs less than 6kg.
  • Sensor unit is back-mounted and has a hand held controller unit.
  • VLF radio wave receiver with frequency range 10 to 30kHz.
  • Serial link for data transfer to microcomputer or printer.


No orientation of the operator with the direction of the transmitter is required. Three magnetic sensors measure the components of the VLF field. The sensor unit has two inclinometers to correct for tilt. The microprocessor automatically takes the measurement. The frequency is keyboard selectable and two frequencies can be measured at the same time. Low noise magnetic sensors and digital filtering produce good measurements even in areas where primary fields are weak. A quality factor is given at each measurement to control the quality of the data.


The classical kilt angle mode, based on the measurement of magnetic-only components, is used to prospect conductive dyke-like structures that generally correspond to weathered or mineralized zones. The resistivity mode is based on the measurement of magnetic and electric components. When working with the resistivity mode, a short electric line and two metaDic electrodes are used. Applications include the prospecting of resistive dyke-like structures, and geological mapping (structural studies).


A large graphic display gives the operator complete information about the measurement: Tilt angle and ellipticity, with their Fraser derivative values (mode 1); resistivity and phase (mode 2). The tilt or resistivity curve is automatically plotted after each station to enable the operator to make a first analysis of the measurements.

Internal Memory

All measured parameters, with frequency value, station and line number, are stored in a solid state memory system capable of containing more than four thousand measuring stations. At the end of the day, or on the field site, data can be transferred to a printer or microcomputer.


VLF radio wave receiver with frequency range 10 to 30kHz. Fully automatic measurement through microprocessor control. Frequency keyboard selectable in 100Hz steps. Two frequencies can be measured at the same time. Two measurement modes:
  • Tilt angle mode—three magnetic sensors with two inclinometers (+ / - 45°).
  • Resistivity mode—one magnetic sensor with one electric line.
Large graphic display (240 x 64 points), with display of:
  • frequency, station and line numbers,
  • Ellipticity and tilt angle (mode 1), or resistivity and phase (mode 2),
  • Quality factor for each measurement,
  • Automatic curve plot for raw or Eraser derivative values.
Data storage in solid state memory. Serial link for data transfer to microcomputer or printer

Standard Components

Sensor console, logger, system software and instruction manual.

Ordering Information

Description Order Number
T-VLF System 500-190-0150
Electric Field Sensor 500-190-0160