The tMag system is a towed array of vector magnetic gradiometers.  Designed for hydrogeologic and archaeologic applications, the array consists of 8 fluxgate vector magnetic gradiometer instruments, comprising 48 total magnetic sensors.  This ultra-high-resolution instrument records data at 200 Hz, resulting in a sample from each sensor every 2.5 centimeters along line, with a lateral sensor spacing of 60 cm.  This allows for nearly 70 hectares per day at an effective line spacing of 60cm.

The vertical gradient is measured directly, with the two horizontal components calculated from the adjacent sensors and the along-line sampling, all corrected for geometry by GPS and accelerometer data.  Thus the full magnetic gradient tensor can be constructed, allowing for extensive numerical analysis and noise reduction.

The system is easily deployed by a two-person field crew and consists of an ATV which tows the array on a sledge.  The system includes processing and analysis software, and has fully-integrated navigation software.

Key Specifications

  • 8 bartington 3-component fluxgate gradiometers
  • 60 cm sensor spacing
  • 2.5 cm sample spacing (200 Hz at 18 kph)
  • 30 cm lower-sensor elevation (adjustable)
  •  Daily production at full resolution: ~70 hectares

Andy Kass