David Skinner & Partners




The most sensitive, commercially available magnetometer available to date.

Potassium Technology GEM Systems GSMP-35 magnetometer and the GSMP-35G gradiometer are the most precise magnetometers on the market today. The GSMP-35 is the result of development since 1980 and provides the highest available sensitivity at 0.0002nT @ 1Hz. The Potassium optically pumped technology allows for extreme gradient tolerance of up to 50,000nT/m.

Why use "K" Magnetometers

Potassium magnetometers work within a narrow spectral line, which means that when they are locked on signal, the error due to heading misalignment is very small. Other alkali vapour sensors, have a much broader spectral line, which translates to larger heading errors. For this reason repeatability between sensors is also the highest possible for Potassium magnetometers over Caesium and other units. This has significant benefits for high sensitivity gradient surveys.

GPS and Navigation

Along with basic GPS tracking, GEM provides a navigation feature with real-time coordinate transformation. A survey ‘lane’ guidance system with cross track display coupled with (optional) automatic end-of-line flag and guidance to the next line allows the operator to navigate seamlessly while carrying out the magnetic survey. Operators can define a complete survey on PC and upload to the instrument or generate parallel line on-site using the internal software.


The GSMP is supplied with a comfortable, lightweight and purpose designed rucksack. The sensors can be mounted vertically on the rucksack or in a vertical or horizontal orientation using the bespoke, horizontal pole system.

  • Sensitivity: 0.0002 nT @ 1Hz
  • Resolution 0.0001 nT
  • Absolute Accuracy ± 0.1 nT
  • Range 15,000 to 120,000 nT
  • Gradient Tolerance 50,000 nT/m
  • Sampling Rate 1, 5, 10, 20 Hz
  • Sensor Angle Optimal angle 35º between sensor head & field vector
  • Proper Orientation 10º to 80º and 100º to 170º
  • Heading Error ± 0.05 nT @ 360º full rotation about axis
  • Storage Mag 3.3 million readings / Grad 2.4 million readings
  • Operating Temperature -40ºC to +55ºC
  • Power 25.9V, 4Ah Lithium Batteries


David Skinner & Partners have built an in-house, small and lightweight magnetometer base station using the Bartington Mag-13MS70 three-axis magnetic field sensor. This unit is ideal for recording diurnal variations during a magnetometer field survey. Self-contained with internal re-chargeable battery.